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GE,S

THE FARMER'S PRACTICAL LIBRARY

EDITED BY ERNEST INGERSOLL

ROADS, PATHS AND BRIDGES

LOGAN WALLER PAGE

TLe Farmer's Practical
Library

EDITED BY ERNEST INGERSOLL
Cloth i6mo Illustrated

From Kitchen to Garret. By VIRGINIA

TERHUNE VAN DB WATER.
Neighborhood Entertainments. By RENEE

B. STERN, of the Congressional Library.
Home Waterworks. By CARLETON J.

LYNDE, Professor of Physics in Mac-

donald College, Quebec.
Animal Competitors. By ERNEST INGERSOLL.
Health on the Farm. By DR. H. F.

HARRIS, Secretary Georgia State Board

of Health.
Co-operation Among Farmers. By JOHN

LEE COULTER.
Boads, Paths and Bridges. By L. W.

PAGE, Chief of the Office of Public

Roads, U. S. Department of Agriculture.
The Satisfactions of Country Life. By

DR. JAMES W. ROBERTSON, Principal of

Macdonald College, Quebec.
Farm Management. By C. W. PUGSLEY,

Professor of Agronomy and Farm Man-
agement in the University of Nebraska.
Electricity on the Farm. By FREDERICK

M. CONLEE.

The Farm Mechanic. By L. W. CHASE,
Professor of Farm Mechanics in the
University of Nebraska.

Ballads of the Countryside. By GEORGE
S. BRYAN.

A GRAVEL ROAD NEAR SAVANNAH, GA.

ROADS, PATHS AND
BRIDGES

BY
LOGAN WALLER PAGE

DIRECTOR, UNITED STATES OFFICE OF PUBLIC ROADS;
PRESIDENT, AMERICAN ASSOCIATION FOR HIGHWAY IMPROVEMENT;

AND
MEMBER, AMERICAN SOCIETY OF CIVIL ENGINEERS

ILLUSTRATED

HJorfc

STURGIS & WALTON
COMPANY

1912

Set up and electrotyped. Published June, 1912

INTEODUCTION

BY THE GENERAL EDITOR

This is the day of the small book. There is
much to be done. Time is short. Information
is earnestly desired, but it is wanted in compact
form, confined directly to the subject in view,
authenticated by real knowledge, and, withal,
gracefully delivered. It is to fulfill these con-
ditions that the present series has been pro-
jected— to lend real assistance to those who are
looking about for new tools and fresh ideas.

It is addressed especially to the man and
woman at a distance from the libraries, exhibi-
tions, and daily notes of progress, which are
the main advantage, to a studious mind, of liv-
ing in or near a large city. The editor has had
in view, especially, the farmer and villager
who is striving to make the life of himself and
his family broader and brighter, as well as to
increase his bank account ; and it is therefore
in the humane, rather than in a commercial di-
rection, that the Library has been planned.

251254

yi INTRODUCTION

The average American little needs advice on
the conduct of his farm or business; or, if he
thinks he does, a large supply of such help in
farming and trading as books and periodicals
can give, is available to him. But many a man
who is well to do and knows how to continue
to make money, is ignorant how to spend it in
a way to bring to himself, and confer upon his
wife and children, those conveniences, comforts
and niceties which alone make money worth
acquiring and life worth living. He hardly
realizes that they are within his reach.

For suggestion and guidance in this direction
there is a real call, to which this series is an
answer. It proposes to tell its readers how
they can make work easier, health more secure,
and the home more enjoyable and tenacious
of the whole family. No evil in American rural
life is so great as the tendency of the young
people to leave the farm and the village. The
only way to overcome this evil is to make rural
life less hard and sordid ; more comfortable and
attractive. It is to the solving of that problem
that these books are addressed. Their central
idea is to show how country life may be made

INTRODUCTION vii

richer in interest, broader in its activities and
its outlook, and sweeter to the taste.

To this end men and women who have given
each a lifetime of study and thought to his or
her speciality, will contribute to the Library,
and it is safe to promise that each volume will
join with its eminently practical information a
still more valuable stimulation of thought.

ERNEST INGEKSOLL.

INTEODUCTION

EOAD building is an art based upon a science.
In the location and survey of roads, the prepa-
ration of plans and estimates, and the selection
of materials, the science of engineering plays
an important part. A reasonably adequate
working knowledge of the art of road building,
however, may be acquired by the layman
through careful attention to the fundamental
principles underlying the building of roads and
the methods which have proved sound in prac-
tice. For instance, proper drainage will con-
vert an impassable quagmire into a reasonably
firm earth road, and a judicious mixing of sand
and clay will utilise the good qualities and neu-
tralise the bad qualities of each.

Bridge construction is much more exclusively
within the province of the engineer than is road
construction, and it is wise economy to incur
the expense necessary to secure engineering
skill in both road and bridge building. There

INTRODUCTION

are times, however, when the farmer finds it
necessary to depend upon his own resources in
the building of small bridges, culverts and
drains. In such cases a practical knowledge of
the simplest theory and practice will often en-
able him to obtain satisfactory results.

It is the purpose of this book to give in a
concise and elementary form the fundamental
principles governing the construction of roads,
paths and bridges for farm and neighbourhood
purposes, and to set forth the details of con-
struction and maintenance so that they may be
followed without great difficulty.

A knowledge of the origin and development
of road building and the progress of road legis-
lation and administration is not only of interest
to the student, but is of real value to every citi-
zen, as it enables him to consider intelligently
proposed reforms in road laws and existing
systems of administration. The opening chap-
ters deal with this phase of the subject and, in
addition, point out a few of the economic aspects
of the road question.

CONTENTS

CHAPTER PAGE

I HISTOBY OF ROAD BUILDING • 3

II ROAD LEGISLATION AND ADMINISTRATION ... 38

III LOCATIONS, SURVEYS, PLANS, SPECIFICATIONS . , 62

IV THE EARTH ROAD 79

V THE SAND-CLAY ROAD Ill

VI THE GRAVEL ROAD 124

VII THE BROKEN STONE ROAD 134

VIII THE SELECTION OF MATERIALS FOB MACADAM ROADS 163

IX MAINTENANCE AND REPAIR 177

The Earth Road — The Sand-Clay Road — The Gravel
Road — The Macadam Road.

X ROADSIDE TREATMENT 207

XI MODERN ROAD PROBLEMS . . .. . . . . .215

XII PATHS 229

XIII CULVERTS AND BRIDGES . ..... 241

ILLUSTRATIONS

A Gravel Road near Savannah, Ga Frontispiece

FACING PAGB

Some Ancient Highways 5

Simplon Pass, Switzerland, Pont Napoleon 12

A Paved Street in Pompeii 12

Holland's Highways 21

Thomas Telford . . 28

John L. McAdam 28

Primitive Methods of Transportation 44

A Toll-house on the National Road 44

Destroyers of Property 49

Economics of Good-Roads Building 53

The Roads and the Schools 60

Examples of Good and Bad Road Location in a Hilly

Region 64

Transformation of an Earth Road 85

An Earth Road with Proper Crown 92

An Undrained Prairie Road in Spring ...... 92

Hoad Machines Hauled by a Traction Engine .... 101

The Sand-clay Road 108

Three Sorts of Good Roads 129

Constructing a Macadam Road 133

ILLUSTRATIONS

FACING PAGE

Bad Road-construction 140

Road-making Machinery 144

Effect of Treatment with a Split-log Drag 181

Good ^nd Bad Maintenance . . . . , . . , .188

Specimen Roads . » , , * . 209

The Automobile and the Road 224

Path of Stone-screenings Beside an Oiled Macadam Road . 230
Concrete Culverts and Bridges 244

ROADS, PATHS AND BRIDGES

CHAPTER I
HISTORY OF EOAD BUILDING

SAVAGE man built no roads. His wants were
few and of an individual character. When
hunger dictated, he sought food in the forests,
or in the streams and lakes, and soon came to
know the regions where game and fish were
most abundant. As time went on he came to
know the best and most direct route to his
sources of supply, and established for himself
definite trails. As he began slowly to mount
the ladder of civilisation his habitation became
fixed, and communication with his own and
other tribes led him to establish more definite
routes of travel. Gradually his trails were
widened so as to admit the passage of beasts of
burden. These widened trails were no doubt
our first primitive roads.

At a much later stage in human development
3

4 EOADS, PATHS AND BEIDGES

came the wheeled vehicle, and the war chariot
was no doubt the precursor of the modern
wagon. In history we find the chariot men-
tioned as early as war itself. The Bible tells of
the pursuit of the fleeing Israelites by Pharaoh
with 600 picked chariots and a host of others.
It is evident from this early general use of the
chariot that roads, even in a somewhat modern
sense, must have been a necessity at a very early
period in our civilisation. The earliest authen-
tic record which we have of stone-surfaced
roads is found in Egypt. A little to the east
of the Great Pyramids of Ghizeh have been dis-
covered the remains of a great causeway, more
than a mile in length. This is supposed to be
a portion of the Great Highway built by King
Cheops for the purpose of affording a passage
across the sands for the transportation of the
stone used in the construction of the Great
Pyramids. This is no doubt the road on which
Herodotus tells us that the Great King em-
ployed 100,000 men for a period of ten years.
It was built of massive stone blocks, which in
places were ten feet thick, and was lined on

SOME ANCIENT HIGHWAYS.

1. (Top.) Appian Way and ruins of the Claudian Aqueduct.
2. Tombs along the Appian Way. 3. Avenue of Sphinxes at Kar-
nak, Egypt.

HISTORY OF EOAD BUILDING 5

either side with mausoleums, temples, parks
and statues.

Ancient Imperial Highways. — Egypt is not
the only land possessing relics of early road
building. Babylon, the city of hanging gardens
and great walls, at a very early date developed
a high state of civilisation, and Semiramis, its
great queen, was an enthusiastic road builder.
It is at this period that we find what is prob-
ably the first use of stone in bridge building,
as the two portions of the city were joined by
a stone bridge across the Euphrates. Strabo
tells us that this wonderful bridge was built
of large stone blocks, joined with plates of
lead. At this period, more than 2,000 years
before Christ, asphalt was used instead of
mortar in constructing the vast walls around
the city. Commerce flourished and great high-
ways radiated to all the principal cities of the
then known world. The highways leading to
Susa, Ecbatana and Sardis, are especially men-
tioned as being lined with travellers and beasts
of burden transporting the wealth of commerce.
It is said that a highway 400 miles long, and

6 KOADS, PATHS AND BKIDGES

paved with brick set in a mortar of asphaltum,
connected Ninevah and Babylon.

The conquering Persians probably learned
the art of road building from the Babylonians,
and instituted a system of military roads
throughout their Empire. The Persians estab-
lished a military messenger or post service, and
at intervals of from 18 to 25 miles stations
were established at which riders, whose swift-
ness Herodotus informs us nothing mortal
surpassed, secured fresh mounts. Their speed
was estimated at from 60 to 120 miles per day.
Strabo states that there were two branches of
the great road leading from Babylon to Syria,
on one of which only a moderate toll was ex-
acted, and it was, therefore, much more fre-
quented by travellers than the other branch.
This is probably the earliest record of the col-
lection of tolls.

As to the details of the construction of these
early roads and the system of maintenance in
effect, we can judge only by inference ; but, as
practically all great works of the ancients of
which we have definite knowledge were con-
structed by forced labour, we must assume that

HISTOEY OF BOAD BUILDING 7

their roads and bridges were built and main-
tained in the same way.

During the time of Solomon two routes from
Palestine to Egypt are mentioned as being
thronged with travellers, and while no direct
mention can be found, several historians in-
form us that the streets of Jerusalem were
paved at least in part during this period. It
is plain that exceptionally good roads must
have existed to carry on the great commercial
trade of the city and to transport the material
required for the splendid temple of Solomon.

The ancient Greeks were by no means igno-
rant of road construction, if we are to judge
from the attention bestowed on the subject by
the senate of Athens and the governments of
Thebes and Lacedaemon. The physical require-
ments of Greece, however, were such as to call
for but few roads. Paved highways are known
to have led from Athens to the Piraeus and to
the sacred shrine at Eleusis. In the ancient
city of Thebes the office of telearch, or cleaner
of streets, was the lowest office in existence.
The ungrateful inhabitants, in order to show
their contempt for Epaminondas because of his

8 ROADS, PATHS AND BRIDGES

failure to capture Corinth, elected Mm to the
despised place. But this citizen, whom Cicero
declared to have been the greatest man of all
times and all nations, held that no man is above
the service he can render to the public, and
soon through his own efforts Epaminondas
raised the office of telearch to be one of the most
distinguished favours the people of Thebes
could bestow. Later, Thucydides informs us
that Archelaus did more for Macedonia than all
his predecessors combined, because he pro-
moted the development of the land by making
roads, and thus contributed largely to making
the interior more accessible.

It was left to the Carthaginians to become
instructors to the world in the art of road build-
ing. Carthage is given the credit of having
demonstrated to the world the strategic and
economic value of improved roads. But for a
splendid system of highways, which permitted
an easy means of communication with all parts
of her domains, she never could have reached
the heights attained, either in commerce or war.
The ready exchange of commerce by land as
well as by sea made her able to withstand the

HISTORY OF EOAD BUILDING 9

terrible drains of long and bloody wars. In
spite of the opposition of Athens and all the
onslaughts of imperial Kome, and even in spite
of the solemn edict, "Carthago delenda est,"
Carthage continued to stand as an ever-ready
menace to Eoman supremacy. But the Bo-
mans were apt pupils. Ere long they saw at
least the military advantage of roads upon
which armies and supplies could be moved with
celerity — a means, as it were, of increasing the
reach of their swords.

There is considerable doubt whether either the
Eomans or the Carthaginians realised to any large
extent the commercial value of their roads. Both
built them more as necessary adjuncts to the success-
ful operations of war, offensive as well as defensive,
than as avenues for commerce. Good roads were, in
fact, the price of existence. They were absolutely
necessary for the rapid movement of troops, as well as
for providing supplies for large armies. Commerce
and exchange followed as a natural result.

We know but little about the Carthaginians as road
builders. In so far as they are concerned their art
is lost. About the ancient ruins of Carthage are
found to-day a few traces of a double road leading
to Tunis and occasional traces of a road leading to-
ward Camarat. These and a few ruins are the only
visible remains of ancient Carthage, for, in spite of

10 EOADS, PATHS AlSTD BEIDGES

the genius of her commanders, her natural develop-
ment and great resources, Carthage was unable to
withstand the continued onslaughts of her great rival.
At last, after nearly 400 years of resistance, offensive
as well as defensive, Carthage fell about 146 B. C.,
and imperial Rome began her mastery of the world.

The Romans as Road Builders. — The Eo-
mans are the first systematic road builders
of whom we have definite knowledge. The
first of their great roads, from Eome to Capua,
a distance of 142 Italian miles, was begun by
Appius Claudius, about 312 B. C., and is known
as the Appian Way, or "The Queen of Eoads."
This avenue was later extended to Brundisium
(Brindisi), or a total of 360 miles, and was
probably completed by Julius Caesar. About
220 B. C. the Flaminian Way was built. This
is of special interest because of a stone-arch
bridge across the river Nar, 60 miles from
Eome. The central arch had a span of 150
feet and a rise of 100 feet, and was pronounced
by Addison as the stateliest ruin in Italy.
After the completion of the Flaminian Way,
road building progressed very rapidly, so that
when Eome reached the height of her glory no

HISTOEY OF EOAD BUILDING 11

less than 29 great military roads radiated from
her gates. As has already been pointed out,
these roads, like those of the Carthaginians,
were built largely, if not entirely, for military
purposes. They represented the visible ef-
forts which the nation by and through her rul-
ers made for her preservation and the exten-
sion of her conquests.

The Eoman roads were, as a rule, laid out in
approximately straight lines. Mountains, hills
and valleys were crossed almost without any
regard to topography. Hills were cut through
and deep ravines filled in. Although these
roads remain to some extent even to-day as
splendid monuments of their builder's art (the
Appian Way is said to have been in good repair
800 years after it was built), we can hardly
credit these people with having intentionally
built for the ages. More than likely the pon-
derous construction they adopted was that
which they, to the best of their ability, believed
necessary for a reasonably permanent and sat-
isfactory road.

The extent of the Eoman road system is
astounding. Every conquered province was

12 BOADS, PATHS AND BEIDGES

soon traversed in all directions with connect-
ing roads. Of the narrow paths, three to six
feet wide, found in conquered Gaul, no less
than 13,000 miles are said to have been im-
proved. In Britain, the road improvement is
estimated to have been at least 2,500 miles.
Across the Alps, through Gaul to Spain, Aus-
tria and the regions of the Danube, led the
great military roads. Nor were the countries
beyond the seas ignored. Straight to the
water's edge led the road from Eome, and then
on the shore beyond was the continuation.
England, Sicily, Africa, and even Asia, all bear
witness of the wonderful energy which strove
to bind firmly every member of the great em-
pire into a living whole.

Nor was this energy directed exclusively
toward imperial progress and the building of
roads for the movement of legions, or to satiate
an empire with the luxuries of remote countries.
If not at first, at least later in her development,
Eome saw in her roads value other than mili-
tary, for in the reign of Augustus we find a
seemingly well-devised system of crossroads
leading to and connecting villages and even

SIMPLON PASS, SWITZERLAND. POXT NAPOLEON.

A PAYED STREET IN POMPEII.

HISTORY OF ROAD BUILDING 13

farms with the great military roads. The
roads were no longer exclusively military, but
were also filling the domestic needs of the
farmers.

The construction proper of the best type con-
sisted of four courses. The statumen or foun-
dation was composed of large flat stones bedded
in mortar. On this foundation was placed a
layer of hand rock laid in lime or cement mor-
tar, known as the rudus. The nucleus consisted
of small stones, gravel, or pieces of brick and
broken tile, laid in mortar. On top of this was
placed the summa crusta, or wearing surface,
of large, flat, closely bedded rocks, making the
total depth of the road about three feet. Un-
der present conditions and prices of labour,
even aided by all our modern machinery, such
roads would probably cost from $50,000 to
$200,000 per mile, and though the Roman roads
were built in part by slave labour and the spoils
of war, they represent an enormous outlay.

The Roman roads, though solid enough to
bear the heaviest loads and durable beyond
question, still lacked many of the essentials of
a good road. The steep grades and their ex-

14 ROADS, PATHS AND BRIDGES

cessive hardness made them very wearisome to
travellers, and Horace informs us that "they
were less fatiguing to those who travelled
slowly. ' ' Even on these roads, which we would
think nothing could injure, we find that the
weight and nature of the traffic were closely
regulated by statutes which were rigidly en-
forced.

The highway legislation of the Romans forms the
basis for our present road laws. By the Roman law,
the use of the roads was for the public. The roads
could be the property of no individual, while the
emperors or other chief magistrates were their con-
servators. The majority of the main highways were
built by contract at the public expense. Their main-
tenance was in part by the labour of soldiers, convicts
or slaves, or by an enforced service which, in some
instances, took the form of taxation. In whatever form
the maintenance was made, it was at the expense of
the district through which the road passed. Tolls as
a means of repairing highways appear to have been
seldom resorted to. Some of the Roman roads were
constructed through the private munificence of her
emperors or other great personages ambitious of
popularity, or with the spoils of war brought home
by successful generals. The supervision of the roads
was entrusted to men of the highest rank. Augustus
himself seems to have made those about Rome his
special care. The crossroads or vicinal roads were

HISTOEY OF EOAD BUILDING 15

committed to the charge of the local magistrates, and,
as a rule, maintained by compulsory labour, or the
contributions of the whole neighbourhood, although
occasionally a portion of a road was assigned to some
landowner to maintain at his own cost.

Roads in 'Ancient Peru and Mexico. — The
countries of the Mediterranean are not the only
ones which have developed systems of roads.
The ancient civilisations of Mexico and Peru
had roads which we are told were in some in-
stances not inferior to those of the Eomans.
The Incas of Peru had a magnificent system,
extending to every part of their vast empire,
but, as far as we can learn, they were largely, if
not entirely, built to accelerate the movement
of troops and supplies. So well did they also
serve an economic purpose, however, that, prior
to the advent of the white man, such a thing
as famine was unknown in Peru. At stated
intervals along the main road were tambus or
caravansaries and storehouses, where provi-
sions were collected for the soldiery, so that the
passage of troops never entailed any additional
hardship on the people along the way. These
roads also served as a system of post roads for

16 BOADS, PATHS' AND BEIDGES

the rapid transmission of government dis-
patches. About every five miles were sta-
tioned runners selected for their speed, endur-
ance and reliability, who acted as carriers.

The most magnificent of the Peruvian roads
was the great mountain highway between the
two capitals, Quito and Cuzco, of which only a
few fragments remain to-day. The younger
Pizarro on first obtaining sight of it exclaimed :
" Nothing in Christendom equals the magnifi-
cence of this road across the Sierra." Hum-
boldt, who viewed the remains in the beginning
of the 19th century, said: " No thing I have
seen of the remains of Boman roads in Italy, in
the south of France and in Spain, was more
imposing than the works of the ancient Peru-
vians, which were, moreover, situated at an
elevation of more than 13,000 feet above the
level of the sea ; ' ' while Cieza, who saw the road
about 1540, compares it to the Koman road in
Spain at that time, which was known as the
"Silver Boad." The length of this magnifi-
cent road is variously estimated at from 1,500
to 2,000 miles, or five or six times the length
of the completed Appian Way. The breadth

HISTOBY OF EOAD BUILDING 17

of the road scarcely exceeded 20 feet. Near
Cuzco we are told that there was a stream of
water and shade trees on either side, while
stone pillars at regular intervals, similar to
European milestones, marked the distances.
Besides the regular tambus there were also at
frequent intervals smaller buildings exclusively
for the accommodation of travellers.

The construction was ingeniously varied with
the requirements of the region traversed. Por-
tions greatly exposed to destructive agencies
were paved with massive blocks of well-cut
stone, sometimes as much as 10 feet wide.
Other regions were paved with a substance not
unlike bituminous macadam, which Humboldt
says "time has made harder than the rock it-
self. " Wide rivers in deep canyons were
crossed on suspension bridges composed of
fibre, some of them being more than 200 feet in
span. In the adaptation of roads to natural
conditions, the Peruvians were superior to the
Eomans. Instead of clinging to the straight
line, the Peruvian roads were adapted to the
topography of the country. No avoidable as-
cents were made. Unavoidable precipices were

18 EOADS, PATHS -AND BEIDGES

scaled by means of steps, and since wheeled
vehicles were unknown and the llama was the
universal beast of burden, this was no serious
obstacle to travel.

Mediaeval Neglect and Its Consequences. —
With the fall of the Eoman Empire, its mag-
nificent system of roads passed into disuse and
neglect. With Charlemagne came a slight re-
vival, but the economic and political conditions
were such as to make this impulse of but short
duration, and the country soon lapsed into
feudalism. Each little community depended
upon itself for the necessities of life. Com-
merce was practically abandoned. The roads
came to be looked upon with dread, and as being
simply avenues upon which the robber barons
might at will swoop down for plunder and
rapine. Seclusion and inaccessibility came to
be considered as in a measure essential to
safety. In many places the roads were torn up
and destroyed in order to prevent the easy in-
gress of robbers and marauders. The little
travel done was on foot or horseback, along
narrow paths or trails.

At this period the old Eoman highways had

HISTOEY OF EOAD BUILDING 19

sunk into the marshes or been overgrown by
forests, and such other roads or paths as ex-
isted are described as having been "in a state
of nature, or worse." A road was simply a
right of way, an unimproved path from one
hamlet to another. Almost all goods were
transported by packhorses. In some parts of
the country wheeled vehicles were entirely un-
known. If the road was extraordinarily bad,
the traveller left it and travelled in the adjoin-
ing field or wood.

At the end of the eleventh century came the
first crusade, which was followed during the
next two hundred years by seven other similar
movements of greater or less magnitude.
Though they failed of their original object, the
crusades were of immense value to the whole
of Europe, in that they promoted intercourse
between the nations, awakened them from their
lethargy, and stimulated commerce and the dis-
semination of knowledge. In order that it
might be possible to move armies toward Syria,
towns made grants, and kings and popes con-
tributed money and issued edicts for the im-
provement of highways.

20 EOADS, PATHS* AND BBIDGES

Revival of Road-Making in Europe. — Com-
mencing with Louis XII in 1508, successive
kings appointed road overseers for the king-
dom of France. These officers bore various
titles at different times. In general, however,
they were charged with the duty of inspecting
the "King's Highways" and repairing them.
Even at this early time the French roads seem
to have been divided into two classes : viz., those
main lines between cities, known as the King's
Highways, and the minor crossroads, under the
charge of the nobles through whose territory
they ran. It appears to have been about the
beginning of the sixteenth century that some
systematic repairs on roads were begun, though
for another 150 years nothing more than filling
up the worst holes was attempted.

In the reign of Henry IV France emerged
from medievalism. Sully, who was appointed
Comptroller of Finance in 1597, was also made
Grand Voyer or Great Way- Warden of France.
Owing to the interest this first of the great min-
isters took in agriculture, a beginning was made
in the improvement of the roads through the
rural districts. Up to that time France had

HOLLAND'S HIGHWAYS.

1. Taking milk to town over a country road in the Netherlands.
2. An interurban road in Holland, made of slag-brick; a cycle-
path and shaded walk on the left and a bridle-path on the right.

HISTORY OF EOAD BUILDING 21

not had a smooth, hard roadway since the Bo-
man supremacy. A few, such as the road
from Paris to Orleans, had a roughly paved
causeway in the centre, but such was the con-
dition that all travel was necessarily by horse-
back. In the winter it was almost impassable
by any means. Under Sully, and later under
Eichelieu, slow progress was made in bettering
the condition of the roads. At the beginning
of the seventeenth century broken stone began
to be applied to the roads for their improve-
ment. In 1661 Colbert was appointed Comp-
troller of Finance, which office carried with it
the superintendence of highways. During his
ministry 15,000 miles of hard road were con-
structed. Such a great work was not accom-
plished without a corresponding hardship to the
people. The old feudal institution of the cor-
vee was used to an extent hitherto unknown.
The peasantry were taken long distances from
their homes and kept at work on the roads even
during seeding and harvest times. Eioting and
insurrection were provoked in various parts of
the kingdom, and the condition of the people be-
came almost unendurable. This system pre-

22 ROADS, PATHS AND BRIDGES

vailed with the utmost rigour until 1774, when
Turgot, who was then Minister of Finance, re-
lieved it of its worst features, but it was not
finally abolished until 1787, when the nation was
on the brink of revolution.

The present magnificent road system of
France was really founded by Napoleon. He
built many roads through the empire, among
others the famous road over the Simplon Pass
in Switzerland, which was commenced in 1800,
and required six years for completion. The
road work of France was systematized and
placed in the hands of a competent and per-
manent body of engineers, and, in order to raise
funds for the continuance of this work, Napo-
leon attempted to establish a toll system on the
best roads. Owing to the determined opposi-
tion of the people, however, the idea was soon
abandoned. From this time on road improve-
ment has been extremely popular in France and
the people have willingly submitted to the neces-
sary taxation.

In 1775 the great French engineer Tresa-
guet published his first treatise on broken-
stone roads. Too much credit can not be given

HISTORY OF ROAD BUILDING 23

to the work of Tresaguet. He was the real
father of modern road building and mainte-
nance, as his work preceded that of McAdam
and Telford by; about forty years.

Pierre-Marie-Jerome Tresaguet was born at Nevers,
France, in 1716, and was made Chief Engineer in
the District of Limoges, July 22, 1764, at a salary of
2,400 francs ($480) per annum. His duties con-
sisted in supervising the construction and mainte-
nance of bridges and highways in the District, and
it was here that he conducted his most important
work. On April 19, 1775, he was made Inspector
General, at a salary of 3,600 francs ($720) per an-
num, and 2,400 francs ($480) for travelling expenses.
Later on in the same year, he was made a member
of the Commission of Inspectors General of France,
but he continued his duties at Limoges for about two
years. He became very famous, and in 1785 he en-
deavoured to introduce his system in Paris. About
this time, however, he fell sick, and his great worth
was recognised by his being awarded a pension of
3,000 francs ($600). During the French Eevolution
this pension was reduced, and, at the age of 80 years,
he found himself reduced to the direst poverty. In
that year the commune of Paris was called on to give
this eminent engineer three pounds of meat daily.
He died in the same year.

In his report to the Assembly of Bridges
and Highways in 1775, Tresaguet pointed out

24 BOADS, PATHS AND BEIDGES

that, although, the ancient highways were of a
thickness of eighteen inches in the middle and
twelve inches at the sides, in six months they
were cut with deep ruts, because of the lack of
maintenance. He suggested reducing the
depth of material in the centre to ten inches,
and that the sides be sloped at an angle of about
20 degrees. Tresaguet laid great stress on
systematic, continuous maintenance as against
intermittent and irregular repairs. It was he
who organised the canton, or patrol system,
which has made the French roads the most
superb in the world.

Development of Road Building in England. —
The first record of road legislation in England
bears the date of 1285, and provides that the
trees and bushes on both sides of the road for a
distance of 200 feet shall be cut away to pre-
vent robbers from lurking therein and rushing
upon their victims unawares. It further pro-
vides that when a road is worn deep another
shall be laid out alongside.

This latter provision was slightly modified by
Henry VIII about 250 years later, who provided that
"two justices of the peace and 12 other men of

HISTOBY OF BOAD BUILDING 25

wisdom and discretion shall choose fresh routes when
the old ones are worn out." In 1346 Edward III
authorised the first toll to be levied for the repair
of roads. This commission was granted to the Master
of the Hospital of St. Giles and to John Holborn,
authorising these parties to levy toll on vehicles pass-
ing on the road leading from the hospital to the Old
Temple of London, and also on an adjoining road
called the Portal. In 1523 Parliament passed its
first act relative to the repair of roads, but it was
not until near the middle of the 18th century that
highway legislation became active. i

The condition of the streets and roads of
England was indeed deplorable during this
time. Street pavements developed somewhat
earlier than rural roads, but even their im-
provement was extremely slow. As late as
1190, we are told that a wind-storm unroofed
the church of St. Mary-le-Bow, Cheapside, Lon-
don, and four pillars 26 feet long, falling verti-
cally in the street, sank by their own weight, so
tbat only four feet remained above the mud.
These were certainly not very inviting streets
for either pleasure or business. Still, it was
not until 1532 that the first statute for paving
in London was recorded.

In this modest act the streets are described

26 KOADS, PATHS AND BBIDGES

as "very foul and full of pits and sloughs, so
as to be mighty perilous and noyous as well
for all the King's subjects on horseback as on
foot with carriages." Nor did this condition
change rapidly. Writing in the year 1770 Mr.
Arthur Young, after a six months ' tour through-
out northern England, says of the turnpike to
Wigan :

"I know in the whole range of language no terms
sufficiently expressive to describe this infernal road.
Let me seriously caution all travellers who may acci-
dentally propose to travel this terrible country to
avoid it, as they would the devil, for a hundred to
one they break their necks or their limbs by over-
throw or breakings down. They will meet with ruts,
which I actually measured, four feet deep, floating
with mud only from a wet summer; what then must
it be in winter? The only mending it receives is
tumbling some loose stones into the worst holes, which
serves no other purpose than jolting a carriage in the
most intolerable manner. These are not only opin-
ions, but facts; for I actually passed three carts
broken down in those 18 miles of execrable memory. ' 9

Still later Lord Macaulay informs us that
the roads were so bad that in places the crops
were allowed to rot in the fields, while only a

HISTOKY OF KOAD BUILDING 27

few miles away people were actually dying of
starvation. With such roads, a few miles
were a more effective barrier than the oceans
are to-day. Not only was commerce practically
impossible, but even the news of dearth or
plenty could travel but slowly.

The legislative effort to better the condition
of the English roads expressed itself in a com-
prehensive system of turnpike acts. It is es-
timated that in 1838 about 1,100 of these turn-
pike trusts were in existence throughout the
kingdom. They proved of little permanent
value, however. Not only their construction,
but also maintenance was often defective. The
cost of collecting the tolls often nearly equalled
the income, leaving little or nothing for main-
tenance. In 1871 the census showed that 5,000
persons in England and Scotland were engaged
in merely collecting tolls. In 1857 Ireland freed
herself from toll gates, and tolls were abolished
in England by act of Parliament, passed in
1878.

Me Adam and Tel ford. — No historical sketch
of the highways of England would be complete
without at least a mention of the two great en-

28 EOADS, PATHS AND BEIDGES

gineers, John London McAdam and Thomas
Telford.

John London McAdam was born at Ayr,
Scotland, September 21, 1756, and spent his
boyhood in New York. He returned to Scot-
land in 1783, and from that time nntil 1798, he
was Trustee of Eoads and Deputy Eoad Lieu-
tenant of Ayrshire. In 1798 he moved to Eng-
land and was made Superintendent of Eoads of
the Bristol District in 1815. He made a most
exhaustive investigation of roads in England,
and he is said to have travelled 30,000 miles and
spent more than five years and £5,000 in in-
vestigating the English roads. He made a re-
port in 1811 to a committee of the House of
Commons, outlining his system. In 1827 he
was made General Surveyor of the Metropoli-
tan Eoads, and in recognition of his success in
improving them, he received a grant of £10,000
from the British Government. His methods
are set forth in the chapter on macadam roads
in some detail. McAdam died at Moffat, in
Dumfriesshire, November 26, 1836. He wrote
two books, which have become classics in road-
building. They are: "A Practical Essay on

HISTOEY OF EOAD BUILDING 29

the Scientific Eepair and Preservation of
Eoads" (1819), and. "Present State of Eoad-
Making" (1820).

Thomas Telford, a civil engineer, was born
August 9, 1757, at Eskdale, Dumfriesshire, and
was the son of a shepherd. At the age of fif-
teen he was apprenticed to a stone mason at
Langholme, where he had an opportunity to
gain an acquaintance with Latin, French and
German. As a young man, he was fond of writ-
ing poems, a number of which were published,
although they were of comparatively little value.
In 1780 he went to Edinburgh, where he was em-
ployed in the erection of houses, and occupied
much of his time in learning architectural draw-
ing. In 1782 he went to London and found
employment in the erection of Somerset House.
This was followed by other work of a similar
character, which eventually resulted in his ap-
pointment as Surveyor of Public Works for the
county of Sallop. His first bridge was finished
in 1792. Later on he was employed in the con-
struction of some of the most important canals
in Great Britain, and was consulted in 1806 by
the king of Sweden regarding the construction

30 EOADS, PATHS AND BEIDGES

of the great Gotha Canal, for which his plans
were adopted. In 1803 he was appointed en-
gineer for the construction of 920 miles of road
in Scotland, most of which was through difficult
country. He also built a system of roads in
the most inaccessible parts of Wales, where he
built a most magnificent suspension bridge
across the Menai Straits. He also built an im-
portant road for the Austrian Government
from Warsaw to Brest. He did very impor-
tant work in the improvement of harbors, and
was generally looked upon as one of the most
eminent engineers of his time. His great work
in the building of roads and bridges has given
him the most lasting fame, and a type of road
which is now quite frequently built on marshy
or unstable ground is known as the Telford
road.

Early Road Work in the United States. —
America, as an abode of the white man, was
still young when she entered the field of road
building and road legislation. The first Amer-
ican road law was passed by the House of
Burgesses of Virginia in 1632. So far as can
be ascertained, the first American road built by

HISTOEY OF ROAD BUILDING 31

white men was at Jamestown a few years later.
We can imagine the conditions somewhat,
both as to means of communication and trans-
portation, when we learn that in 1625, when the
British Crown took over Virginia from the
London Company, the inventory revealed the
interesting fact that the Governor alone had a
horse.

In the North the so-called New England Path, be-
tween Boston and Plymouth, was begun in 1639. In
the province of New York, regulations for road build-
ing were passed in 1664, and two years later the first
Maryland road law came into existence. Pennsylvania
followed some years later (1692) with a road act
placing the control of the highways in the hands of
the townships which, however, was amended eight
years later, whereby the control was given over to
the counties. To Pennsylvania is also given the
credit of the first important macadam road built in
America — the Lancaster turnpike from Lancaster to
Philadelphia — which was constructed in 1794. Por-
tions of this road are still operated as a toll road.

The extent and character of these early roads may
perhaps be judged more clearly from the state of the
postal service. It was not until 1673 that a post
service was established between New York and Bos-
ton, and three days were required for the trip.
Twenty-two years later, in 1695, letters were for-

32 BOADS, PATH'S AND BBIDGES

warded only eight times a year from the Potomac to
Philadelphia. In 1717 mail from Boston to Wil-
liamsburg, Virginia, was delivered every four weeks
in summer and every eight weeks in winter, and as
late as 1790, the number of post-offices in the United
States numbered onfy 75.

Thus, at the time of the organisation of our
Government, highway construction can scarcely
be said to have begun. The few roads, if they
may be dignified by such a name, were mostly
the result of chance — mere trails which had
gradually been widened to admit the passage
of vehicles, but were usually almost impassable
during long periods. Systematic organisation
for either construction or maintenance did not
exist, and each little community was left to cope
with the problem as best it could.

Civilisation was rapidly pushing toward the
great West, however, and the need of roads be-
came imperative.

The first wagons crossed the Alleghanies within
two years after the close of the War of the Revolu-
tion. The need for better roads had now become so
strong that private capital was attracted and numer-
ous toll roads were constructed throughout the dif-
ferent States. By 1828 nearly 2,380 miles of these

HISTOEY OF EOAD BUILDING 33

roads had been constructed in Pennsylvania alone,
at a cost of $8,431,000. Few, if any, of the turn-
pikes returned sufficient dividends to make them a
profitable investment, as one of the chief drawbacks
was the high cost of maintaining toll gates and col-
lecting the tolls. Nor did the turnpikes suffice to
fill the demands of the time. In 1821 the cost of
transporting a barrel of mackerel from Philadelphia
to Somerset was $8 per hundred pounds, and from
Philadelphia to Pittsburg the rate was $11, or 70
cents per ton-mile. Not until about 1865 were the
railroads of sufficient extent to make themselves felt
as considerable factors in the wholesale reduction of
long-distance freight rates. By this time the charge
for hauling freight from Baltimore to Wheeling on
the turnpike road was reduced to 17 cents per ton-
mile.

Our national legislators early recognised the
need of adequate means of communication and
transportation, and after a lengthy debate an
act was passed in 1806 providing for the build-
ing of a great highway from the Atlantic to
the Mississippi. Beginning at Cumberland,
MdL, on the Potomac, this great highway passed
through the States of Maryland, Pennsylvania,
Ohio and Indiana, westward to the Wabash and
the Mississippi. For thirty-two years the Gov-
ernment struggled with this great enterprise

34 EOADS, PATHS AND BEIDGES

until finally the appropriations ceased alto-
gether in 1838, and the work was discontinued
after an expenditure of $6,824,919.33 appropri-
ated by Congress.

President Monroe once vetoed the appropriations
for the National Turnpike, as well as a bill introduced
by John C. Calhoun, providing for setting aside the
dividends from the National banks for road purposes.
Revenues derived from the sale of public lands, how-
ever, continued to be set aside by Congress for aid
in road construction. Between 1811 and 1845 Lou-
isiana, Indiana, Mississippi, Illinois, Missouri and
Iowa were aided in this way to the extent of about
$5,000,000. Between 1854 and the beginning of the
Civil War Congress appropriated in all something
like $1,600,000, which was expended chiefly on roads
within the territories. Thus, up to 1861, the National
Government had assisted in road building throughout
the Nation to the extent of about $14,000,000.

Since 1861 the National Government has
rendered aid to road building only in an edu-
cational sense. For a time following the war
the immense debt incurred made appropria-
tions from the National treasury almost out
of the question, and besides, the idea had be-
come quite prevalent that the railroads had
lessened the need as well as value of improved

HISTOEY OF EOAD BUILDING 35

roads. It required some time for the country
to discover the error and it was not until the
advent of the bicycle that the good-roads move-
ment awoke from its lethargy.

Government Aid. — An office of road inquiry
was established under an act of Congress, ap-
proved March 3, 1893, making an appropriation
of $10,000 to the Department of Agriculture for
making inquiries in regard to systems of road
management throughout the United States, and
for making investigations in regard to the best
methods of road-making, preparing didactic
publications on this subject,, and assisting the
agricultural colleges and experiment stations in
disseminating information.

The work of the office was at first of neces-
sity very limited. In 1897 the construction of
short sections of sample roads under the super-
vision of skilled road builders was begun in a
small way in co-operation with the various agri-
cultural experiment stations. In December,
1900, a laboratory for testing the physical
qualities of different road-building materials
was added. Two years later the annual ap-
propriation was increased to $20,000, and pro-

36 EOADS, PATHS AND BEIDGES

vision was made for the investigation of the
chemical and physical character of road materi-
als. The language of the appropriation bills
has remained practically unchanged up to the
present time, except that the name of the office
was changed from Public Eoad Inquiries to the
Office of Public Eoads, and a statutory organisa-
tion provided in the agricultural bill, approved
March 3, 1905.

From this modest beginning the work of the
office has gone along in a careful and conserva-
tive manner.

Local communities can easily avail themselves of
the assistance granted by the United States Office of
Public Eoads. It is necessary only for the local au-
thorities having jurisdiction over the roads to make
application either to the Secretary of Agriculture or
the Director of the Office of Public Roads for the
assignment of an engineer or expert to investigate
local conditions with reference to the roads, and to
give such advice and instruction as may be necessary.
The salary, and in most cases the expenses, of such an
engineer are paid by the National Government, and
hence his services are free to communities. The
road-material laboratories of the Office of Public
Eoads make tests to determine the relative value of
road material, without cost to any citizen of the

HISTORY OF ROAD BUILDING 37

United States who will take the trouble to write to
the Office and obtain the necessary forms and ship-
ping blanks for submitting samples of material. The
only expense to be borne by the private individual is
the transportation charge on the material to the
Office.

Within recent years the investigative work
of the Office of Public Roads has attracted
world-wide attention, and the testing laborator-
ies are looked upon as equal to, if not superior
to, any in existence.

CHAPTER II

EOAD LEGISLATION AND
ADMINISTRATION

in its strict interpretation a principle
is defined as a fundamental truth or doctrine,
we are at liberty, in dealing with this subject, to
regard a policy which has been followed by
many agencies over long periods of time and
with successful results as being fundamental,
and, therefore, to be considered in the light of a
principle.

Applying this reasoning to the information
afforded by the histories of the road systems of
all countries, it becomes evident that one of the
features common to all of the successful road
systems of history is centralisation of authority
and responsibilities. The most striking exam-
ple illustrating the power of centralisation is
afforded by the splendid roads of Rome. No
sooner had the power of the imperial city crum-
bled away and the management of her splendid

EOAD LEGISLATION 39

roads passed into the hands of many nations
than the roads began to deteriorate, because of
the utter absence of attention. The most con-
spicuous example in modern times of an efficient
system of roads well constructed, maintained
and administered is the road system of France.
Beginning with the humble patrolman, the sys-
tem provides definite lines of authority through
various grades upward to the Inspector-General
at Paris, whose guiding hand directs the whole
organisation, prevents duplication of effort and
co-ordinates all efforts and all accomplishments
In the United States the States which have
made most progress in the actual improvement
of the public roads are those which have in some
degree centralised the construction and care of
the roads in a State official or officials.

Until comparatively recent years most of the
States of the Union have followed a policy di-
rectly opposed to the policy of centralisation.
The laws all provided, and in many States
continue to provide, for a large number of
officials, each having a very limited territory
under his control, and each being, in a measure,
independent of any direct supervision. This

40 EOADS, PATHS AND BRIDGES

policy of extreme localisation has, by its very
failure to produce adequate results, confirmed
the wisdom of a centralised system.

In the light of this evidence it seems clearly
demonstrated that each State should provide a
centralised direction of its road work, and,
pending that time, each county should, as far as
possible, centralise the control of its road work
in a competent official, and, carrying this reason-
ing still further, it is safe to say that each
township could with profit place its work under
the direction of a competent employe or official
rather than to depend upon a number of officials
whose authority is not defined and whose duties
overlap.

A second important point which has been
brought out clearly by the experience of all na-
tions, and which has been emphasised most
strongly since the development of modern traffic
conditions is the necessity for special knowl-
edge and skill on the part of the men who
actually build and maintain the roads. It is a
curious fact that, although the public road is
conceded to be so important to humanity as to
be classed with the home, the church, and the

EOAD LEGISLATION 41

school, and although its condition directly
affects the welfare of all who are called upon to
traverse it, and indirectly all who are dependent
upon the products which are transported upon
it, few people give more than a passing thought
to the methods by which the road is built and
maintained, while it is an inborn conviction on
the part of nine men out of ten that they are
thoroughly competent to say how a road should
be built and maintained. If the general public
would consider that to build a successful road
a suitable location must be found, grades re-
duced where necessary, a drainage system pro-
vided, suitable material selected, foundation
and surface arranged with great exactness, cul-
verts and bridges constructed, and, to meet
modern traffic conditions, the whole subject of
bituminous and other special binders dealt with
from the standpoint of the expert, there would
be more inclination to employ for such work
men who make a profession of highway en-
gineering. It is very difficult to find in any of
the road laws of this country, except those that
provide for State Highway departments, any re-
quirement that the officials having charge of the

42 EOADS, PATHS AND BEIDGES

road work shall possess any special qualifica-
tions. Hence the enormous waste of public
funds through ignorance of correct methods, as
well as from the lack of centralised authority.
Skilled supervision is an essential in road work,
and should be considered a fundamental re-
quisite applicable at all times, under all con-
ditions, and by all units of government. It is
just as necessary for the township to employ a
man with a knowledge of road building rather
than one who has no knowledge of the subject,
as it is for the State to require its highway enr
gineer to be competent and experienced.

Roads Belong to the Public. — That the roads
belong to the public and that their use and con-
trol should remain with the public is a principle
recognised by Eome in the management of her
great system of highways, and which has per-
sisted in all of the civilised countries of Europe,
and has finally been recognised throughout the
United States, in spite of costly and elaborate
experiments with the toll-road system, particu-
larly in England and in this country. The
Eomans never approved the plan of giving over
any of the public roads to the control of private

KOAD LEGISLATION 43

individuals or companies, and few, if any, tolls
were ever collected on Eoman roads. The Eng-
lish Parliament in the latter part of the eight-
eenth century passed innumerable turnpike acts,
and for a good many years during the eighteenth
and nineteenth centuries the toll-road system
was supreme in England. It broke down under
the fierce resentment of the public, and because
it was costly and clumsy in operation. The cost
of collecting the tolls was totally out of pro-
portion to the amount actually spent in main-
tenance. Toll roads were abolished finally in
Great Britain in 1878. In this country the be-
ginning of the nineteenth century witnessed
very great activity in the building of pikes or
toll roads. Here, however, as in other coun-
tries, the experiment proved unprofitable and
contrary to the public welfare, with the result
that this system has been gradually abandoned,
until at the present time the toll road is de-
cidedly the exception rather than the rule in
the United States. The toll system is funda-
mentally wrong because it places under private
control that which must of necessity be a public
utility; it places the burden of taxation solely

44 EOADS, PATHS AND BEIDGES

upon the users of the road, and leaves untaxed
those who benefit materially from the improve-
ment of the road, although having no occasion
to make use of it for travel. An example of this
is to be found in non-resident owners of tracts
of land abutting the road and increasing in
value by reason of the improvement. Finally
the toll system is unprofitable to the stockholder
and excessively burdensome to the traveller, be-
cause of the great cost of collecting the tolls and
conducting the system, which makes the divi-
dend low to the stockholder and the rate high to
the traveller.

Personal Service on Roads Inadvisable. —
From ancient times the practice has been gen-
eral among all nations to compel personal serv-
ices on the roads, or to accept personal services
in lieu of a cash tax. Under the ancient des-
potic monarchies slave labour was largely used,
and under the Bourbons of France the peasants
were compelled to contribute a number of days '
work on the public roads. Modern standards
of humanity discountenance these rigorous
methods, but they exist in another form through
what is known as the statute-labour system.

PRIMITIVE METHODS OF TRANSPORTATION.

A TOLL-HOUSE ON THE NATIONAL ROAD.

EOAD LEGISLATION 45

Under this system the laws require that each
able-bodied citizen perform a given number of
days' service upon the road, or coin mute this
labour tax in cash, while in many States of the
Union, even the taxes that are payable in cash
may be paid in labour at a given rate per day.
This inadequate system is entirely out of
harmony with modern business practice and
modern governmental policies. It provides un-
trained labourers who are not amenable to dis-
cipline and who render their services grudgingly
and in as scant a measure as possible. They
are at the same time employers and employes,
because it is by their votes that the road offi-
cials are kept in power. In consequence they
dominate their leaders and the results which
they accomplish are almost negligible. Hence
it has come to be essential to efficiency in the
administration of our public roads that all road
taxes be paid in cash, so that regular employes
may be obtained, who may be required to give a
full and honest day's work, who may acquire
the skill essential to efficiency, and who may be
answerable to reasonable discipline. We can
hardly consider it, however, a maxim that road

46 EOADS, PATHS AND BEIDGES

taxes should be paid in cash, regardless of all
conditions. It has been claimed that in some
of the Southern States it is impossible to collect
cash taxes, and the only recourse is to compel
personal services on the part of a large element
of the population. It must be understood that
such examples constitute exceptions, and that
recourse to the payment of road taxes in labour
is justified only in extreme cases.

The problem of what to do with the convicts
and other offenders against society has been
one which has vexed the students of sociology
for centuries, and it is now universally conceded
that idleness is extremely detrimental to the
prisoner, and by reason of his unproductive-
ness, burdensome to the public. Outdoor pro-
ductive labour is conceded to be beneficial to the
prisoner mentally, morally, and physically, and
to make possible a return to society for its out-
lay. As to the character of work which should
be performed by the convict, it is reasonable to
assert that as the prisoner has offended against
the public, his labour should be for the benefit
of the public, and directed toward public im-
provements. In this way, he is not only pro-

EOAD LEGISLATION 47

moting the public welfare, but he is also enter-
ing into competition to the least possible degree
with honest free labour. The volume of public
improvements is necessarily limited, and com-
prises, among other improvements, the construc-
tion of roads and the preparation of road mate-
rials. Certainly no public improvement upon
which the convict can be employed will yield a
greater amount of benefit to the public than the
improvement of the roads, and wherever this
form of labour is applicable, it should be em-
ployed. In the South excellent results have
been obtained by using convicts in actual con-
struction of roads. In some other States the
convicts have been employed in stockades in the
preparation of road materials. Conditions are
such in some of the States as to make the wis-
dom of using convicts in this way questionable,
but the plan should not be rejected without the
most thorough consideration.

Roads More Than Local Institutions. — By
reason of the many inventions of modern times
which have tended to shorten distance and time,
which have enormously increased manufactures,
and which have made possible the concentration

48 EOADS, PATHS *AND BEIDGES

of a large percentage of our population in cities,
and because of the growth of education, the gen-
eral dissemination of learning, and the broader
field of knowledge afforded to the people of civ-
ilised nations in the present day, the isolation
of local communities has been largely super-
seded by the intercommunication and interde-
pendence which link together communities hun-
dreds of miles apart. The road is no longer a
merely local institution, for over it must be
transported the food products which are neces-
sary for the existence of the city dwellers, and
the manufactured products which come from
the city to the country dwellers. This road
may be traversed by the automobilists from
other neighbourhoods and other States, and by
the transient guests of the summer hotels and
resorts. The condition of this road affects the
welfare, not only of the people who live near it,
but of all those other classes of people who have
occasion to buy the products of the surrounding
country, or to sell to the inhabitants, or to make
use of the road as transients. This condition
has given increasing importance to the maxim
that all who share the benefits of road improve-

DESTROYERS OP PROPERTY.

1. A mudhole on a r '."d in a Virginia township which voted down
bond-issue. 2. A hill-road in another short-sighted community.
Ruined wagons about a blacksmith shop where roads are unimproved.

EOAD LEGISLATION 49

ment should share the burdens incident to such
improvement. This maxim has found concur-
rent expression in the establishment of State
highway departments and the appropriation of
State funds to aid in the improvement of the
main travelled roads. State aid is justified, not
only on the ground that it distributes the bur-
dens in proportion to the benefits, but also be-
cause it provides a centralisation of authority,
skilled supervision, and the public control al-
ready referred to as essentials, and as a result
of these factors, economy, co-ordination and
tangible results in the way of construction and
effective maintenance follow.

Importance of Systematic Maintenance. —
Effective maintenance of the roads is rather a
result than a system and, if the other essentials,
namely, centralised skilled supervision, cash tax-
ation, public control, and the utilisation of con-
vict labour, be adopted, it is probable that
effective maintenance will follow. It is well to
state here, however, that almost without excep-
tion no provision has been made in the United
States for the maintenance of roads, even those
which are most perfectly constructed and which

50 EOADS, PATHS AND BEIDGES

would, therefore, seem to justify some outlay
for the maintenance of their high state of effi-
ciency. It is just as careless and unwise to
leave a good road uncared for as it is to leave a
well-constructed building to the mercy of the
elements and depredations of the public. The
strongest feature of the French road system is
the constant care of the roads which have already
been constructed. The whole system of main
roads is divided into short sections of from 2%
to 5 miles approximately, and each section is in
charge of a patrolman, who gives his entire time
to the road, repairing slight defects as soon as
they occur, keeping the ditches open, trimming
the trees and bushes, removing dust and de-
posits of sand and earth after heavy rains, and,
when ordinary work is impossible, he prepares
stone and transports it to where it is needed.
In order to facilitate this repair work quantities
of crushed stone and gravel are placed at con-
venient intervals along the road, while to meet
the expense of this maintenance annual appro-
priations are made, based upon careful esti-
mates by the engineers in charge. Mainte-
nance, to be effective, must be systematic or in

KOAD LEGISLATION 51

accordance with some definite plan or purpose,
and must be continuous, instead of at long in-
tervals, as we practise it in this country.

Financing Public Roads. — The methods of
financing road improvement constitute a very
important part of the subject. Eliminating as
unwise and impracticable the toll system and,
except in extreme cases, payment of road taxes
in labour, it follows that there are only four
ways of obtaining revenues for improving the
roads, namely, a cash property tax, a poll tax, a
bond issue, and a State appropriation, the latter
of which may be derived from one or many
sources. There may be special methods of ob-
taining revenue which are applicable only in
special cases, such, for example, as private sub-
scription, the sale of public property, the appro-
priation of certain license taxes, etc., but as a
general proposition the four sources of revenue
already named must be depended upon. It is
manifest that State aid cannot be given in suffi-
cient amount to meet the needs of the respective
counties. Poll taxes may not be available, as
the law may provide that they be expended for
other than road improvement. Even where this

52 EOADS, PATHS AND BEIDGES

form of revenue is available, it is usually neces-
sary to supplement it with some other form of
revenue. This brings us to the consideration of
the relative advantages of making only such im-
provements as may be possible by means of an
annual cash tax, and the making of improve-
ments on a large scale by means of a bond issue.
It may be said in favour of bond issues that they
bring immediate returns in the form of im-
proved roads and in such amount as to enable a
large proportion of the population to enjoy the
benefits of this improved medium of transporta-
tion without having to wait a long period of
years. The improvement necessarily develops
the resources of the locality more quickly and
thereby increases wealth. The cost per mile of
road is lowered by reason of the magnitude of
the enterprise, while the cost of maintenance is
materially decreased because it is easier to
maintain a long stretch of improved road con-
necting two communities than it is to maintain
short sections of improved roads, the ends of
which ravel or disintegrate more quickly be-
cause of the fact that the remainder of the road
extending from each end of the improved sec-

EOAD LEGISLATION 53

tion remains unimproved. A bond issue gen-
erally places upon the next generation a portion
of the burden, but this is contended to be equita-
ble by reason of the fact that the wealth thus
developed inures to the benefit of the generation
called upon to bear a portion of the burden.

A bond issue should never be considered a
wise undertaking simply because it is a bond is-
sue, nor should it be considered unwise for the
same reason. The needs of the community in
the way of improved roads, the financial condi-
tion of the community, the necessary outlay to
obtain this improvement, and the probable re-
sultant benefits, compared with the resultant
burdens, should always be considered. The
Office of Public Eoads of the United States De-
partment of Agriculture maintains a corps of
engineers who are qualified to examine local
conditions intelligently, and recommend a plan
of improvement and outlay commensurate with
the needs and the ability of the localities which
they are called upon to advise. The services of
these engineers are given free by the Govern-
ment. Moreover, in many of the States having
State highway departments, assistance of this

54 BOADS, PATHS AND BEIDGES

kind can be secured without cost. It is recom-
mended, therefore, that the expenditure of large
sums of money be based upon such careful and
conservative advice.

Road Economics. — Economics deal with that
phase of the road subject which has to do with
the relation between the outlay for road im-
provement and the returns in the form of bene-
fits. The question to be considered in all cases
is not whether the outlay is large or whether the
benefit is indirect, but whether the resultant
benefit, either direct or indirect, is greater than
the outlay. The amount to be expended can
easily be ascertained by means of specific desig-
nation and conservative estimates of the im-
provements proposed to be made. The methods
of providing the necessary revenues can be de-
termined and the necessary administrative re-
quirements made along the lines indicated in
the preceding paragraphs. It remains, there-
fore, to consider what benefits may be expected
to arise from the proposed improvements, and
what distribution of the improvements will af-
ford the greatest amount of benefit to the great-
est number of people.

EOAD LEGISLATION 55

In the first place the improvement of the road
may be expected to lower the cost of hauling,
greatly increase facilities for transportation,
and add to the comfort of those who must use
the road for these purposes. As a basis for
considering this phase of the subject it may be
stated that in 1906 the Bureau of Statistics of
the Department of Agriculture obtained data
which indicated the average cost of hauling to
be 23 cents per ton-mile, and the average haul
9%o miles. In the report issued by that Bureau
it was stated that although ocean rates were
higher than usual during the year 1905-1906,
the mean charge for carrying wheat by regular
steamship lines from New York to Liverpool
was only 3%0 cents per bushel, or 1%0 cents less
than it costs the farmer to haul his wheat 9%o
miles at 19 cents per ton-mile, from his farm to
a neighbouring railroad station. Moreover, the
cost for hauling wheat is less than the general
average for all products. It is generally known
that the load which two horses can draw on a
smooth, hard road is double and sometimes
treble the load which they can draw on an earth
road. Engineers have made investigations on

56 EOADS, PATHS AND BBIDGES

this point which indicate that the difference in
cost of hauling upon broken-stone roads, dry
and in good condition, and an earth road con-
taining ruts and mud, is the difference between
8 cents per ton-mile and 39 cents per ton-mile.
Since the introduction of motor vehicles this
cost has been still further lowered, and a special
demonstration of motor trucks in California
yielded a rate of about 2% cents per ton-mile.
It is manifestly impracticable to improve all of
our roads by surfacing with hard material, but
such an extensive improvement is unnecessary,
because of the fact that repeated investigations
have shown that 20 per cent, of the roads carry
90 per cent, of the traffic.

From the standpoint of the farmer, the in-
creased loads which his team can draw, the pos-
sibility of making a greater number of trips per
day, and the decreased wear and tear on his
team, his equipment and himself should furnish
powerful arguments in favour of road improve-
ment.

Practical Value of Road Improvement. — In
determining upon the location of proposed im-
provements a careful traffic census should be

EOAD LEGISLATION 57

taken, so that the most heavily travelled roads
may receive the most thorough improvement,
and the other roads be improved according to
their importance.

Increase in the value of lands adjacent to the
public road invariably follows a marked im-
provement in the road. This increase is un-
questionably genuine and not, as many persons
claim, a fictitious increase arbitrarily assumed
by the assessor, and which imposes upon them
an unwarranted increase in taxation. If the in-
crease were fictitious, the farm would have no
greater market value than it had before. As a
matter of fact the farm, if it were put upon the
market, would command a better price than if
the improvement had not been made. The very
fact that market and shipping points are made
more accessible to the farm makes the latter
more valuable to the prospective purchaser.
This point should need no argument to support
it, and rests upon the same reasons which make
a lot on an active business street in a city more
valuable than a lot of equal size on a little-fre-
quented side-street. The fact that more land can
be cultivated, that more profitable crops can be

58 EOADS, PATHS AND BEIDGES

grown, that regular delivery of such perishable
products as milk and cream, small fruits, truck
products, etc., is made possible adds materially
to the value of the land. If the owner sells after
the improvement he reaps the benefit of the in-
creased valuation. If he retains the land and
cultivates it under this improved condition, his
yield in income is greatly increased, to say
nothing of his comfort and happiness. Exam-
ples are numerous of farm products that have
gone to waste because the expense of transport-
ing them to market was greater than the amount
which would be derived from their sale. Cen-
sus statistics show that vegetables yield a re-
turn per acre about six times as great as the
cereals, while small fruits yield a return over
eleven times as great as the cereals. Neither
of these two products can be grown to advan-
tage except near a good road over which they
can be delivered regularly, quickly, and in good
condition to the consumer.

That the agricultural regions which are
afflicted with bad roads are not utilising their
resources as they should has been ascertained in
numerous investigations. A striking example

EOAD LEGISLATION 59

of this was found in an agricultural county sit-
uated within easy reach of the cities of Wash-
ington, Baltimore and Eichmond. The roads
of the county were almost impassable at certain
seasons of the year, and as a consequence most
of the agricultural land was untilled. An in-
spection of the records of the local railway sta-
tion at the principal town in the county revealed
the fact that the incoming shipments of farm
products such as could be produced within the
county, exceeded the outgoing shipments by
nearly 5,000 tons. In other words, the people
of that particular county were actually buying
from outsiders the food products which they
should be producing and selling.

A factor which should be considered in deal-
ing with the subject of road improvement is the
effect of such improvement upon population
and the labour supply. The last census figures
show that over 46 per cent, of our population
live in cities of 2,500 inhabitants or more. The
boys are leaving the farm for the more attrac-
tive surroundings of the city. The immigrant,
instead of settling in the country and thereby
affording an adequate labour supply, is stay-

60 EOADS, PATHS AND BEIDGES

ing in the city, and by this unhealthy crowding
is lowering the standard of living and of citizen-
ship, and increasing the cost of living by in-
creasing the ratio between the producer and the
consumer of food. The rural sections which
are improving their roads are not losing in
population as are other sections. In an inspec-
tion of the returns from the census of 1900 it
was found that in 25 counties selected at ran-
dom showing an average of only 1% per cent,
of improved roads, an actual decrease of 3,112
persons to the county occurred between the
years 1890 and 1900 ; while in 25 other counties
having 40 per cent, of their roads improved,
located in the same States, an increase of popu-
lation took place in the same period averaging
31,095 for each county.

Better roads mean better schools, because the
attendance is greater and the possibility for
fewer buildings and more graded schools is
increased. This point is manifested by inves-
tigations made by the Government which show
that in 5 States having a small percentage of
improved roads, 59 out of each 100 of the pupils
enrolled regularly attended the schools ; while in

THE ROADS AND THE SCHOOLS.

EOAD LEGISLATION 61

5 States having a very high percentage of im-
proved roads, the attendance was 78 out of each
100 enrolled. In some prosperous communities
having good roads the little one-room school-
houses have been supplanted by six- and eight-
room, graded schools, and a sufficient amount of
money saved to provide conveyances for taking
the children to and from school.

The benefits of road improvement are inca-
pable of exact enumeration and definition, but
they directly or indirectly affect the life of the
rural dweller in every way. If he goes to
church the condition of the road has its effect.
If illness occurs in his family, the effect of the
road is the relative quickness with which med-
ical aid can be secured, and, in many cases, this
also affects the cost of medical attention. The
social intercourse with neighbours, and the
pleasure of driving or automobiling depend
upon the condition of the roads. All of these
considerations must be taken into account when
the question of road improvement is to be de-
cided, and they must be weighed against the
burdens incident to the improvement to be
made.

CHAPTEE III

LOCATIONS, SUEVEYS, PLANS,
SPECIFICATIONS

Location. — A road should be so located as
to permit the passage of traffic from one given
point to another with the least possible ex-
penditure of time and energy, but due consid-
eration must be given to the initial outlay in
the construction, and the subsequent outlay in
the maintenance of the road, so that the total
cost will not be greater than the resultant bene-
fits. It must be apparent that many factors
enter into the problem, frequently making it
difficult for even the most skilled and thorough
engineers to determine the right course to
pursue.

The economic considerations involved in
road location are of two kinds: First, those
relating to the accommodation of traffic; sec-
ond, those relating to the road itself. The
first deals with the utility of the road to the

LOCATIONS, SPECIFICATIONS 63

community, while the second deals with the cost
of construction and maintenance of the road.
In the consideration of the traffic requirements,
due weight should be given to the relative popu-
lations dwelling along possible lines of loca-
tion, the possibilities of development, agricul-
tural and otherwise, following the location of
the road, the necessity of shortening the dis-
tance between given points and, lastly, the con-
siderations of pleasure and recreation. The
second consideration deals with the relative
difference in cost among the various possible
routes both for construction and maintenance,
and involves not only the question of grades,
and the availability of materials, but also the
type of construction necessary.

In general the most economic location of a
road is that over which the annual cost of
transportation, the annual cost of maintenance
and the interest on the first cost of construction,
together with the annual sinking fund, are
lowest. Thus, it will be seen that the problem
of road location is one dealing largely with
financial considerations which must be given

64 KOADS, PATHS AND BEIDGES

precedence over considerations of an engineer-
ing character.

It is ordinarily held that the following prin-
ciples should be observed in deciding on the
final location of a road :

1. Follow the route having the easiest grades.

2. Select the shortest and most direct route
commensurate with easy grades.

3. Avoid all unnecessary ascents and de-
scents.

4. Cross ridges in lowest passes.

5. Cross over or under railroads: a grade
crossing means danger to every user of the
road.

6. Cross streams at most favourable sites,
and as nearly at right angles as possible.

7. Carry the balancing of cuts and fills only
so far as it will reduce the cost of the total
earth work to a minimum. When more earth
is needed for a fill, it can readily be secured
by slightly widening the cut, and where the
cuts are in excess, convenient wastage can
readily be found by widening the nearest fill.

8. Do not overestimate the advantage of
straightness. The curved road around a hill

LOCATIONS, SPECIFICATIONS 65

is often no longer than the straight road over
it. In addition, a more or less sinuous course
is an advantage from a maintenance stand-
point, as on a winding road the wheel traffic
has a tendency to spread over the entire sur-
face, which is seldom the case on a straight
road, particularly when the crown is high.

9. Under modern conditions of traffic, sharp
curves are a source of constant danger. The
radii of curves should never be less than 100
feet, and as low as this only where an unob-
structed view can be had of the road ahead.

10. Carry the road along the southern or
western slope of ridges, if possible, so that it
may be least exposed to storms and dry out
more quickly after heavy rains and the melting
of snow.

Surveys. — The purpose of a survey is to se-
cure the necessary data for determining the
best location, as defined above, to supply such
other data as may be needed in the prepara-
tion of the plans and estimates of cost, and
finally, together with the specifications, to
serve as a guide in the actual construction of
the road. The cost of the survey will vary

66 KOADS, PATHS AND BEIDGES

greatly with conditions. In the construction
of an improved road through a new territory
where the route is not clearly defined by natural
topography, several surveys may be necessary,
while if it involves the improvement of an al-
ready existing road, the location of which can
not be altered except to a very limited extent,
a single survey may be sufficient. The more
extensive surveys are usually divided into three
parts : the reconnaissance, the preliminary, and
the final survey.

The reconnaissance is a more or less rapid exam-
ination of the region to be traversed, for the purpose
of obtaining information as to the general feasibility
of the proposed route, and to secure the data neces-
sary for the rapid and intelligent prosecution of more
detailed surveys, should they prove necessary or ad-
visable. Reconnaissance should, in general, include
the examination of an area rather than of one or
more routes. This is especially true where the road
is of any considerable length, for, having familiarised
himself with the entire area, the engineer will find no
difficulty in choosing the one or more lines for which
more detailed surveys are needed in order to deter-
mine the final location. For this work the topo-
graphical sheets of the United States Geological Sur-
vey are extremely valuable, and if the region in ques-

LOCATIONS, SPECIFICATIONS 67

tion is covered by such a survey, a copy should, by
all means, be secured. The topographical sheets,
covering approximately an area 30 miles square, can
be obtained from the Superintendent of Documents,
for the sum of 5 cents each. Sometimes a study of the
topographic map will make it possible to dispense with
the field reconnaissance entirely, or at least reduce it
to a minimum.

In making the reconnaissance the following
data should be carefully noted and recorded in
the field book: The location and approximate
elevation of all low passes; the general trend
of all ridges and streams; the inclination of
the rock strata; conditions as to dryness, etc.
Advantageous bridge sites should be deter-
mined; all sources of supply of road material,
stone for concrete, water supply, etc., should
be carefully noted.

The reconnaissance should determine on one
or more lines to be surveyed in detail in order
to establish finally the best and most econom-
ical route. For these lines an instrumental
survey is necessary, or at least advisable.
This survey should be accurate enough to mark
the exact location of the proposed improve-
ment on the ground, and also to obtain all neces-

68 KOADS, PATHS AND BEIDGES

sary data for plotting the map and preparing
profiles, estimates of the earth work, etc.

The survey usually consists of a transit line with
levels and cross-sections taken at every station and
at such intermediate points as may be necessary to
give the required accuracy in computing the earth
work. Full notes are also taken in regard to the
width and character of all streams crossed, low and
high water marks, all crossroads, private ways, the
character of the soil and of any material suitable for
road metal or use in constructing culverts or bridges
which may be found in the neighbourhood.

Plans. — The surveys should furnish all data
for supplying drawings from which the esti-
mates can be closely computed. The necessary
drawings consist of a map or plan of the road
and as much of the contiguous territory as may
be desirable, a profile and a number of cross-
sections. If bridges, culverts or retaining
walls are necessary, fully detailed drawings
must also be made for these structures.

The survey-notes should be so complete that
the map, cross-sections, and profile can be
plotted rapidly and with sufficient accuracy.
It is the poorest kind of policy to depend on
the memory to supply lacking data. Every-

LOCATIONS, SPECIFICATIONS 69

thing should be taken in full in the field and
entered in the notebook.

The completed plans should be clear, con-
cise and full of information. The profile
especially should be a veritable encyclopaedia
of information, both for the engineer and the
contractor. It should show the present ground
line, the finished grade, the depths of cuts and
fills, the points of change of grade, location of
all crossings and watercourses, together with
elevation of high and low water levels, etc.

The scale to which the drawings should be
made will depend largely on the amount of de-
tail to be shown. For most general purposes,
a scale of 100 feet to the inch for the map and
of 100 feet to the inch horizontally and 40 feet
to the inch vertically for the profile will be
found convenient. Where much detail is to be
shown, or on very difficult sections, this scale
may be enlarged to any desired extent.

The layman is apt to belittle the value of
the preliminary work done on the surveys, and
in making of plans, etc.; yet these are of the
utmost importance and are absolutely neces-
sary for an economical solution of the ques-

70 BOADS, PATHS AND BEIDGES

tions involved. A few extra days spent in this
preliminary study of conditions will often re-
sult in the saving of large sums of money, not
only in the actual construction and in the
maintenance of the road itself after it has been
built, but in securing a much better route
than one which might be secured without such
study. Many of the questions involved in
highway location are of an extremely difficult
nature to solve, and it is needless to say that
hard problems cannot, as a rule, be correctly
solved without the requisite time and study.

The following instructions for making road
surveys are used by the Office of Public
Eoads, United States Department of Agricul-
ture:

INSTRUCTIONS FOR MAKING ROAD SURVEYS

All surveys for roads which it is proposed to im-
prove with the cooperation of this Office should be
made strictly in accordance with the following rules :

All notes should indicate the date on which each
part of the survey is made, the names of the men per-
forming the work and the weather conditions. All of
the work should be plotted and accompanied with a
complete copy of the notes.

LOCATIONS, SPECIFICATIONS 71

TRANSIT AND LOCATION SURVEY.

1. The transit line should be established following
approximately the center of the road. At every
hundred feet on this line temporary points are
to be established. A spike driven into the road
through a piece of red cloth or tape is a station
mark that can be easily found after several
weeks. The measurement of this line is to be
made either with a steel chain or tape, with a
degree of accuracy of 1 in 3,000.

2. Wherever it is necessary to make a bend in the
transit line, the transit instrument is to be set
up at the bend, and the angle of the course
ahead with that of the rear course measured,
always measuring from the back sight around to
the right. The angles are to be measured to the
nearest minute, and where local disturbances do
not preclude doing so, magnetic bearings of each
course should be observed.

3. Opposite the points established in the road, and
on the side far enough removed to be clear of
all construction work, stakes are to be driven.
These stakes should be about 24 inches long, and
driven for a depth of 12 to 15 inches. The
stakes are to be numbered, beginning with zero,
each hundred feet to be a unit. The offset dis-
tance of centre of stake from the station point
on the transit line is to be measured and recorded
in the notes to the nearest 0.10 foot.

4. At all bends stakes should be set on both sides

72 EOADS, PATHS AND BRIDGES

of the road in a line through the point of de-
flection and at right angles with the back course.
These stakes will be used as reference stakes and
should have a small nail driven in the top from
which measurements to the nearest 0.01 foot are
to be taken to the deflection point in the transit
line. Reference stakes should be driven flush
with the ground and another stake driven near
by for a marker.

5. As a rule, deflection points should be made at
even stations or half stations, a half station
being designated by the number of the previous
station with + 50.

6. After the location of the transit line as described,
offset measurements are to be taken at each sta-
tion or as much oftener as may be necessary to
locate properly the sides of the travelled way and
fences or walls alongside the road wherever such
exist.

7. Measurements should be taken so as to locate all
bridges, culverts and cross drains of whatever
description, and the direction of flow through
them should be shown by an arrow. The clear
opening of all waterways should also be indi-
cated.

8. The location of all crossroads and private en-
trances should be indicated.

9. Landowners' names should be obtained and di-
viding fences, where such exist, should be located.

LOCATIONS, SPECIFICATIONS 73

LEVELS.

After the transit and location survey is made the
levels are run as follows :

10. Permanent bench marks at either end of the
work and at convenient intermediate points are
to be established well out of the way of any con-
struction. The number of bench marks should
be at least four or five to the mile and as much
oftener as convenience may require. Bench
marks should be on permanent objects on which
a rod can be conveniently held, and located
where they can be readily identified on the
ground. The roots of trees with low-hanging
limbs are not convenient, nor is a point so far
back from a line of trees along a road as to shut
off all view of the bench mark, except directly
opposite it.

11. A line of check levels should be run touching
every bench mark, and separate notes kept of
these check levels. Elevations should check to
0.10 foot per mile. All readings on bench marks
and turning points should be to nearest 0.01
foot.

12. Headings for ground elevations should be to
nearest 0.10 foot. Ground elevations are to
be taken at the centre of the road at each station
or 100 feet and as much oftener as may be neces-
sary to show irregularities in the profile or cross-
section.

13. At each place where a centre reading is taken

74 ROADS, PATHS AND BRIDGES

side readings are to be taken to show accurately
the cross-section of the road.

14. To take a cross-section, first take reading of the
rod on the top of the stake at that particular
station and a ground reading at same point.
Enough readings are to be taken at other points
across the line of the road to show the true shape
of the banks, gutters and ditches on each side
and the road between. The distance of each
reading from the transit line is to be recorded
as well as the reading itself.

15. Elevations are to be taken of the following
points :

a. The bottom of openings at each end of
all culverts, indicating them as east and west or
north and south ends.

b. Bridge floors, tops of abutments and bridge
seats.

c. The entrance and exit ditches on stream
bottoms about 25 feet from either end of a cul-
vert or bridge, so as to give the grade of the
stream bed near the culvert.

d. High and low water in streams (estimated).

e. "Water surface of streams as found.

PLAN Scale— V = 40'

PROFILE Vertical Scale — 1" = 4'

Horizontal Scale— V = 40'

CROSS-SECTIONS Scale — 1" = 4'

Note. — A profile of road with a grade of more than
4 per cent, should be plotted with a vertical scale
of 1" = 8'.

LOCATIONS, SPECIFICATIONS 75

Specifications. — The purpose of a set of
specifications is to set forth in clear and un-
mistakable language the work to be done, the
manner of doing it, and the character of the
materials to be furnished. Usually the spec-
ifications, together with the engineer's esti-
mate, form the basis on which the contractors
bid, and after the contract has been let, the
specifications serve as a guide for both con-
tractor and engineer in the further prosecution
of the work. In how much detail the various
operations are to be specified will depend upon
conditions. Sometimes it may be advisable
simply to set forth certain standards to which
the finished work shall conform. In this event,
the manner of carrying on the work is left en-
tirely with the contractor. "When there are
unknown or hazardous conditions, such as are
sometimes met with in the construction of
foundations for bridges, or erecting bridges
over streams subject to violent floods which
may endanger the work in progress, it
may at times be considered preferable to
let the contractor assume the risk. In this
case, however, great care should be taken to

76 EOADS, PATHg AND BRIDGES

secure a contractor of known integrity and re-
sponsibility.

More often, however, not only the standard
to which the finished work is to comply, but
also the character of the materials which are to
enter into the construction, as well as the man-
ner in which the work is to be carried on, are
prescribed. Oftentimes the specifications are
made so complete as to form a perfect formula
for the contractor to follow. It should be kept
in mind, however, that under such conditions,
if for any reason the finished work does not
comply with the requirements, the contractor
cannot be held legally responsible so long as
he has substantially complied with the various
specifications. The courts have ruled that a
man cannot be held responsible for the results
of his work when he is not given any choice in
the manner in which it must be done, but must
follow regulations in every detail.

The specifications when drawn should be ex-
amined, first as a whole, and then each clause
separately. No conflicts or ambiguities must
exist, and nothing should be inserted which is
not necessary. It is a good rule to specify only

LOCATIONS, SPECIFICATIONS 77

what is really wanted, and to write these speci-
fications so clearly that there can be no mis-
take as to what is desired. One clause which
is nearly always found in all specifications
for road building involving any considerable
amount of excavation, and which has in the past
caused more friction than almost any other
single clause, is that pertaining to the classifi-
cation of the earth work. Quite often three
classifications are given, as earth, loose rock,
and solid rock, and sometimes a fourth is
added — that of hard pan. These classifica-
tions are in themselves all well and good, but
the difficulty comes in describing the different
classifications in such a manner that in the
field one class may be readily distinguished
from the next. Because of this difficulty it
would seem advisable in road work to limit the
classification of earth work as much as possi-
ble. The drawing up of proper specifications
is no small part of the work of the engineer,
and the manner in which they are drawn will
often not only save endless friction and hard
feelings during the progress of the work, but
save much money to the community. They

78 BOADS, PATHS AND BEIDGES

may seem simple at first glance, but the writing
of proper specifications requires knowledge,
skill, experience and ability.

CHAPTER IV
THE EAETH EOAD

ACCOKDING to a careful mileage census made
by the U. S. Office of Public Eoads, there were
in 1909 about 2,210,000 miles of road in the
United States, of which upwards of 2,000,000
miles may be classed as earth roads. It is
evident from this showing that the task of sur-
facing all of our roads with hard material, or
even the major portion of them, is so great as
to be impossible of accomplishment for a great
many years to come. The best that we can do
is to classify the roads so that only those which
carry the heaviest traffic will be surfaced with
hard material, while the remainder will be
given such simple and efficient treatment as to
render them capable of meeting requirements
at small outlay.

Already an enormous traffic is carried over the
country roads in the United States, estimated at not

80 ROADS, PATHS AND BRIDGES

less than 250,000,000 tons annually. Impressive as
this tonnage appears, it is but a fraction of the traffic
which our country roads would be called upon to sus-
tain if they were in fairly good condition. Proof of
this is found in the experience of France, where an
official census has brought out the fact that the public
roads carry one and one-third times as much freight
as the railroads. According to the reports of the In-
terstate Commerce Commission, the railroads of this
country carry upwards of 900,000,000 tons annually.
If our public roads were used to the same extent as
the French roads, it would mean a traffic of about
1,200,000,000 tons annually instead of the 250,000,000
tons, as at present.

An earth road may be defined as a road com-
posed of natural soil, to which no other kind
of surfacing material has been applied, and
with which no binder or filler has been mixed.
It differs from a sand-clay road to the extent
that the latter is composed of sand and clay
mixed in suitable proportions.

Location. — It is important that the road be
located so as to serve the needs of traffic best,
to permit due economy in construction and
maintenance, to obtain a grade as nearly level
as practicable, and to permit thorough drain-
age. The considerations which should govern

THE EAETH EOAD 81

the location of roads are fully dealt with in
Chapter III. By far the greater proportion
of our roads have been located at haphazard,
in many cases following Indian trails, paths
of wild animals and farm boundaries. This is
particularly true in the Eastern States, which
were settled first. The result is that instead

T&XXL SECTION FOR S/De-ff/jLLAND Gfwxm.-SL0nE LOCATIONS.

of the roads being adapted to the traffic require-
ments, the traffic is compelled to adapt itself to
the road. In the West the roads are laid out
on section lines. These sections are all square,
and consequently the roads are all at right
angles. If a person desires to cross the coun-
try, it is necessary for him to follow the
boundaries of a series of rectangles, instead
of going directly to the point he desires to
reach. If it were possible to relocate the pub-
lic roads according to the needs of traffic and

82 KOADS, PATHS AND BKIDGES

agricultural development, so that distances
might be shortened and easier grades obtained,
our total mileage could be cut down at least
100,000 miles, and communication rendered far
less difficult and costly in every section of the
country. Such general relocation is impossi-
ble, and the best that can be done is to avoid
unwise location of new roads, and to relocate
old roads whenever conditions require and per-
mit.

Grades. — The term " grade, " as used in this
chapter, means the slope of the road along its
length. A steep road would be described as
a road having a steep grade. Among road
builders the grade is expressed in terms of
percentage, as 1 per cent., 5 per cent., 10 per
cent. ; each per cent, meaning a rise of 1 foot in
each 100 feet of length.

In the construction of new roads and the re-
grading of old roads it is customary to specify
a certain per cent, as the maximum grade al-
lowable at any point on the road. A minimum
grade means the least that can be allowed for
good drainage. A number of considerations
are influential in determining the maximum

THE EAETH EOAD 83

grade which may be allowed, but the most im-
portant is expense, as it is necessary to adapt
the work in hand to the means available. The
topography of the country has an important
bearing on the question of grades, as a much
more nearly level road can be specified in a
flat or rolling country than in a mountainous
region. The character of the soil also has
some bearing upon the question. By common
consent it is agreed among highway engineers
that no road should exceed a grade of 5 per cent,
except in extreme cases where, by reason of
natural difficulties or lack of funds, it is im-
practicable to reduce the grades to that point.
Steep grades are a powerful handicap to
traffic, and wherever possible they should be
eliminated. While it is a matter of common ob-
servation that the load which a team of horses
can draw on a steep hill is very much smaller
than the usual load on level ground, it is not
generally known that on an average macadam
road it requires approximately four times as
much power to draw a load up a 10 per cent,
grade as is required to draw the same load on a
level. This means that an eight-horse team

84 EOADS, PATHS AND BRIDGES

would be required to draw up a 10 per cent,
hill the same load that two horses could draw
on a level road. It may be said, in modification
of this, however, that for short distances a horse
is able to exert about twice his natural pull, so
that if the grade were short, four horses might,
by exerting their maximum pull, accomplish the
same result. But the loss of tractive power on
steep grades is greater than shown by theory,
since the power of a horse decreases very rap-
idly on steep inclines. The leading authorities
on highway engineering express the matter
about as follows: Assuming 1,400 Ibs. to be
the load which one horse can draw on a level
earth road, he should be able to draw 650 Ibs.
on a 5 per cent, grade and 340 Ibs. on a 10
per cent, grade, with about the same degree of
ease.

While it is frequently expensive to obtain
easy grades, the fact should be borne in mind
that the work is permanent in character. No
matter what surface material may be applied to
a road, it will wear out and have to be replaced.
Not so with the grade; it is a permanent step,
not only toward the building of a good earth

TRANSFORMATION OF AN EARTH ROAD.

1. (Top.) Present condition, improved by drainage and a macadam
surface. 2. Past condition, sunken and water-soaked.

THE EAETH EGAD 85

road, but also toward any type of improved
road which may be determined upon at some
later time. A steep road is much more difficult
to maintain than a road with a flatter slope, as
the former is much more likely to be damaged
by the action of water, which tends to wash and
gully the surface. The injurious action of
horses' hoofs and narrow-tired, heavily loaded
wagons is also more pronounced on steep
grades.

There are three ways by which an easy
grade may be obtained: First, to locate the
road so that it will go round the hill, instead of
over it; second, to have it run diagonally up
the face of the hill, doubling back and forth a
sufficient number of times to keep the grade
down to the desired per cent.; third, to cut
down the hill.

Another plan, which might be considered a modifi-
cation of the second, is to begin the ascent of the hill
quite a distance from the base. It is a matter of
common observation that many country roads run
straight to the base of a hill before beginning the
ascent. In almost every case they could, by leaving
a straight line some distance back, approach the hill
on an easy grade. The question of cost will largely

86 BOADS, PATHS AND BEIDGES

'determine which of these three methods should be
adopted. If the hill is a long one, it will usually
be found cheaper and more practicable to go around
it. This will not necessarily result in lengthening the
road, as shown by the familiar example of the bucket
bail, which is the same length when resting on the
rim of the bucket as when in a vertical position. If
the hill is short, it will probably be cheaper and more
satisfactory to cut it down, using the material from
the cut to fill in the approaches on each side. Where
the road leads from lower ground to a plateau, the
method of carrying a road up the face of the hill
diagonally will sometimes be found most feasible, but
each case must be decided in conformity with the
local topography.

If it is necessary to lengthen the road to even
a considerable extent in order to secure easy
grades, it may be found in many cases to be
real economy to do so. The same energy which
would be expended by a horse in drawing the
load up a steep grade would suffice to draw it a
far greater distance on a comparatively level
road. Many scientific tests have been made to
demonstrate this in exact terms. The point
will be made sufficiently clear, however, by the
statement that to lift a ton a distance of one
foot requires an expenditure of energy amount-

THE EAETH EOAD 87

ing to 2,000 foot-pounds. Therefore, in draw-
ing a ton a distance of 100 feet on a 10% grade,
the load would have to be lifted ten feet, in-
volving an expenditure of 20,000 foot-pounds of
energy, and all this is in addition to the force
required to draw the load a distance of 100 feet
on a level. It must, therefore, appear that the
burden imposed by distance is not nearly as
great as that imposed by steep grades. Of
course it should be borne in mind that a mate-
rial lengthening of the road may add to the
cost of construction and the cost of mainte-
nance. The best course is to give due weight
to all factors in the problem.

Drainage. — Water is destructive to all roads,
and particularly to earth roads, so much so
that good drainage is the keynote of success in
road construction. To remove quickly the
water which reaches the surface of the road,
and to intercept the flow of water from higher
grounds toward the road, a system of surface
drainage must be provided. Water attacks the
foundation of the road as well as the surface,
in many cases, and to meet this danger sub-
drainage must be provided. The subject of

88 KOADS, PATHS* AND BEIDGES

drainage is, therefore, subdivided into surface
drainage and subdrainage.

Surface Drainage. — Most country roads are
too flat to shed water; in fact, many of them
are concave, owing to the fact that traffic is kept
consistently in the centre and wears down the
surface until the road is more in the nature of
a ditch than a highway. As the roads are usu-
ally repaired only once or twice a year, grass
and weeds are permitted to grow close up to
the travelled way, still further preventing the
flow of water from the road to the ditches.

If the road is comparatively level, so that the
water stands upon it, the surface soon becomes
soft, causing deep holes and ruts to form under
the impact of traffic. When this incipient
damage is done, every heavy rain thereafter
hastens the destruction of the road, because the
water follows the wheel ruts, widening and
deepening them. Eventually, if preventive
measures are not taken, this will totally de-
stroy the road. In any event, under such con-
ditions the cost of repair will be large.

This damage to the surface can be easily
prevented by giving the road a crown or slope

THE EAETH EOAD 89

from the centre to the sides sufficient to cause
the water to drain quickly to the side ditches,
instead of running down the middle of the road ;
but it is necessary to exercise judgment in
determining upon the slope or crown to be
adopted. If the crown is made too steep, the
water will rush off to the side so quickly as to
cause damage to the shoulders or sides of the
road. If it is too slight, the water will flow
down the centre instead of to the sides. In a
perfectly flat country a somewhat slighter
crown is necessary than on the hillsides, be-
cause in the former case there is no tendency
of the water to flow down the centre, while in
the latter case the slope at the sides must be
at least equal to the longitudinal slope. Other-
wise, the water will follow a diagonal course
and may carry off some of the surface material.
The best practice is to allow a slope, averaging
from % inch to 1 inch to the foot, but the indi-
vidual judgment is necessary to determine
whether it is advisable in specific cases to in-
crease or decrease these standards slightly.
The road builder should avoid the mistake of
crowning his roads too steeply, not only because

90 EOADS, PATHS 'AND BRIDGES

of the consequent damage to the shoulders, al-
ready referred to, but because in such cases the
wagons will " track" or keep to the centre and
eventually cause the road to be flat or hollowed
out on the most heavily travelled portion.

A natural mistake is sometimes made by
reason of the literal following of text-books in
giving a uniform slope from the centre to the
sides, which results in making the road like a
roof, in which the centre of the road forms the
comb. In actual practice the road should be
curved and the total slope from centre to sides
should be such as to give the required average
slope per foot. By actual measurement it might
appear that the slope will be only % of an inch
to the foot near the centre and considerably
more than an inch to the foot at the side of the
road. This is all right, as long as the road
maintains its convex shape. On sharp hillside
curves it is usually advisable to give a single
inward slope to the road.

Ditches. — The next most important point in
providing for surface drainage is to construct
suitable side ditches. All these side ditches
should have a fall or slope of at least six inches

THE EAETH EOAD 91

in each 100 feet in length ; if the fall is less, the
water will not flow quickly enough and trouble
will be had, particularly in winter or early in
the spring when the snow melts. These side
ditches must be ample in size to provide for
the greatest volume of water that may reason-
ably be expected by reason of heavy rains,
storms or the melting of snows. In order to
provide sufficient capacity, the ditches should
be made wide, rather than deep, as deep ditches
beside a road are dangerous to traffic and are
more expensive to construct and maintain.
The best plan is to have frequent outlets from
the ditches, either by means of culverts, pipes,
or by turning the ditches into lower ground,
rather than to allow the water to flow along the
road any great distance.

Five 12-inch pipes in a mile of roadway are about
as cheap and far more effective than one 24-inch pipe,
because the water is disposed of before it gains force
or headway or has time to damage the road. The
maximum velocity for a 24-inch vitrified tile, flowing
full without head on a grade of 1-inch per 100 feet, is
3.6 feet per second, or about 2y2 miles per hour;
when the grade or slope is increased to 36 inches in
a distance of 100 feet, the velocity becomes 20 feet

92 BOADS, PATHS AND BRIDGES

per second, or about 13% miles per hour. The dis-
charge for the 24-inch pipe in the first instance, will
be 5,086 gallons per minute, while in the second in-
stance it will be 28,260 gallons per minute. It will,
therefore, be seen that a 24-inch pipe, laid on a grade
of 36 inches to the 100 feet, will have over five times
the capacity of the same pipe laid on a grade of 1
inch to the 100 feet.

Under the same conditions, the maximum velocity
for a 12-inch tile on a grade of 1 inch per 100 feet,
equals 1% feet per second, or about % of a mile per
hour, and for the same tile on a grade of 36 inches to
the 100 feet, the velocity would be 7y2 feet per second,
or about 5% miles per hour. The discharge for the
12-inch tile in the first instance would be 442 gallons
per minute, and in the second instance 2,650 gal-
lons per minute, or about five times as much. It will
thus be seen that comparing the 12-inch pipe and
the 24-inch pipe on a grade of 36 inches to the 100
feet, the five 12-inch pipes would remove in the aggre-
gate 13,250 gallons per minute, as compared with
28,260 gallons per minute by the one 24-inch pipe,
but the advantage of the former lies in the fact that
the water is removed at five points instead of one.

Another important point in the foregoing is,
that by increasing the grade or slope of the
pipe, the capacity for removing the surface
water is enormously increased. In order to
protect culverts or pipes from damage, when

AN EARTH ROAD WITH PROPER CROWN.

AN UNDRAINED PRAIRIE ROAD IN SPRING.

THE EAETH ROAD 93

discharging water under full pressure, or when
a culvert or pipe is given a considerable slope
or grade, it is desirable that the joints be
cemented, if a pipe is used, and that the ends
of the culverts be protected with masonry, or
concrete wing walls. In addition to this the
spillway should be paved with cobblestones, in
order to prevent washing. Another point in
favour of having a sufficient fall or slope to the
culverts is that they will be self -cleansing and
so keep open. A culvert laid flat may soon fill
up.

Mud-holes cannot be successfully drained, as
a rule, with culvert pipes. The best plan is to
throw out the soft mud and replace it with good
firm earth, so that it becomes level after con-
solidation with the surrounding surface. The
ditches should then be sufficient to drain the
mud-holes and carry the water to the culverts.

The sides of these ditches should have an
easy slope, particularly on the side of the road,
as this will tend to prevent accidents to traffic,
as well as the caving in of the banks of the
ditches. The construction of deep ditches
should be avoided. In most cases ditches made

94 EOADS, PATHS AND BEIDGES

with the road machine in shaping up the surface
of the road is sufficient for surface drainage.

Culverts should be built at the low points
where outlets are available and existing streams
should always be utilised for outlets, when pos-
sible. Where only a slight volume of water
is to be removed from ditches, it may be carried
under the road in tile pipes instead of concrete
culverts. In such cases the pipes should be
laid deep enough to prevent their being broken
by the traffic. If it is impossible to place the
pipes deep enough to be removed from the
effect of traffic, it is well to use concrete. The
construction of small culverts and drains will
be more fully explained in a separate chapter.

Suldrainage. — Many thousand miles of pub-
lic road in the United States are located on low,
swampy ground, or on ground which possesses
very poor natural drainage. A large percent-
age of prairie roads are in bad condition for
several months each year, by reason of a wet
subsoil. In such cases surface drainage, no
matter how effective, will not always serve to
keep the road in good condition. Conse-
quently, it becomes necessary at times to install

THE EAETH EOAD 95

a system of underdrainage, so as to clear the
soil of surplus water and to give the road a
solid, dry foundation. Water in the subsoil
becomes ice in winter and expands, thereby
heaving the road. In the spring the ice melts
and the foundation becomes softened to such
an extent that the whole road gives way, or,
as it is generally stated, "the bottom drops
out of the road." It can readily be seen that
the maintenance of roads under these condi-
tions is exceedingly difficult and very expensive.
Underdrains can usually be provided at small
expense and will last quite a long time, if prop-
erly maintained. Many roads are greatly dam-
aged by springs in the soil. These should be
tapped by blind drains of stone or pipe, and
the water carried diagonally to the side ditches.
Hillside roads are often subjected to the de-
structive action of water, which drains from
the higher ground into the foundation of the
road. Surface drainage is, in some cases, suf-
ficient to protect the road. Where it is not
sufficient, the best plan is to dig a deep ditch
some distance above the road on the hillside,
of sufficient capacity to intercept and carry off

96 KOADS, PATHS AND BEIDGES

the flow of surface water. This ditch should
be given outlets to lower ground at frequent
intervals.

The usual method of underdraining a road
is to provide a narrow trench on each side at
the bottom of which a pipe of from 4 to 6 inches
in diameter is placed. Ordinarily a 4-inch
pipe will be found sufficient. These pipes are
usually composed of terra cotta tile. The
depth to which these pipes should be laid de-
pends largely upon the character of the soil and
the depth of the frost line, but in general it
should be about 3 or 4 feet. The pipe should
be laid near the bottom and the trench then
filled with broken stone, gravel or broken brick-
bats. The pipe should have a fall of not less
than 6 inches for each 100 feet of length. It
is unwise to give too much fall to small drain
pipes, as the swift current may wash away the
ground about the drains and displace them.
The sides of the trenches should slope gradu-
ally, as this will prevent the ground from cav-
ing in and will also give greater stability to the
drain pipes. The outlets or spills for the pipes
should be paved so as to prevent washing.

THE EAETH EOAD 97

Care should be taken to lay the tile true to
grade as, otherwise, it will soon become in-
effective. Wherever the pipe sags it will soon
be filled with sediment, and if there is a crest
the silt will accumulate immediately behind it.
The ends of the pipes should be covered with
an iron grating, which will prevent vermin from
entering.

Where pipe drains or concrete culverts can
not be provided, it is sometimes practicable to
construct blind drains with flat stones.

Some authorities recommend a line of tile
under the centre of the road, but this is not prac-
ticable as a rule, as it is much more expensive,
and involves a greater amount of digging, both
in the original installation of the pipe and in re-
pairs, should they become necessary. Further-
more, if the road is later on surfaced with hard
material, it will become increasingly expensive
to reach the pipe for repairs.

A method which may be practised to advan-
tage in soil which is free from rock and easily
worked, and where the ground is practically
level is to grade the road up in the form of an
embankment above the level of the surround-

98 EOADS, PATHS AND BEIDGES

ing country. The water may then drain from
the road instead of to it.

Width of Road.— The width of right of way
is specified in most of the States by statute, but
is usually not less than 40 and not more than
66 feet. The width of the travelled roadway is
much less, as allowance of at least six feet on
the outside of each ditch should be made for
footways. It is advisable to have the road
wide enough to meet all traffic requirement, but
it is a mistake to have the travelled way ex-
ceptionally wide, as this will necessitate deeper
ditches, and will not only be more costly to con-
struct but also to maintain.

Clearing Roadway. — After determining the
width of roadway, ditches and footways, the
next step is to remove all stumps, brush, roots,
rocks, etc.

Cuts and Fills. — The practical road builder
always endeavours to establish the grade of the
road so as to make the cuts and fills equal, as
otherwise waste of material will result. If the
cuts are greater than the fills, the result will be
a greater amount of loose earth than can be
used, while if the fills are greater, it will be nee-

THE EABTH BOAD 99

essary to obtain additional earth from bor row-
pits and haul it to the road. Some of the cuts
and fills are so far apart that it is cheaper to
obtain material from the side of the road, or
to waste the material from the cuts, rather than
endeavour to balance the cuts and fills.

An important point to be considered in connexion
with excavation is that loose earth at first occupies
greater space than compact earth, while the final re-
sult is that there is considerable shrinkage in fills.
It is a curious fact that the earth in a fill or embank-
ment actually compacts to less space than it occupied
in its original position. The amount of shrinkage
varies with the character of the soil and is about as
follows: Gravel or sand, 8 per cent.: clay, 10 per
cent.; loam, 12 per cent.; loose surface soil, 15 per
cent. ; and puddled clay, 25 per cent.

The side slopes on cuts and fills must be
given an angle which will insure stability and
at the same time cause the least waste of mate-
rial. The method of determining the angle of
the slope is by the ratio of the horizontal dis-
tance to the vertical distance. We can assume
the side of the embankment to form the hy-
pothenuse of a right-angled triangle. If the
vertical line of the triangle is 1 foot and the

100 EOADS, PATHS AND BEIDGES

base line extending out to the point of the slope
is 1% feet, the slope should be designated as
iy2 to 1. The slope will, of course, vary with
the nature of the soil. Common earth will
stand a slope of 1 to 1, but it is safer to make it
iy2 to 1. Gravel requires a slope of 1% to 1,
while clays vary widely, ranging from 1 to 1 to
a slope as flat as 6 to 1. In general practice
the slope of 1% to 1 is found best. It is well
to sow grass seed on slopes, or, if that is not
practicable, to sod them, as greater stability
will be obtained in this way.

For slight cuts and fills, where the soil will permit,
it will be found that the road machine or road grader
is sufficient; where the soil is hard or mixed with
pebbles or field stone, it is frequently found to be
economy to use a road plough and follow it with the
road grader. For excavation on a larger grade
the slip scraper is exceedingly useful, and where the
cuts and fills are considerably apart the wheel scraper
will be found most useful. The wheelbarrow is
rarely used, except for small jobs or in wet, swampy
places. The elevating grader is frequently used to
advantage in prairie regions and in low, flat ground
free from rocks, as it elevates the road above the
surrounding country, and thereby promotes good
drainage. It can also be used to advantage in load-

THE EARTH EOAD lOT

ing wagons on cut-and-fill work. Road-building
equipment and its use are taken up in detail in a
separate section of this chapter.

When the roadway has been cleared and
brought to a desired grade, careful examina-
tion should be made of the surface at all points,
and wherever it is found to be soft, spongy,
or insecure, the soft material should be re-
moved and replaced with good, firm earth,
sand or gravel. The material should then be
tamped in place until the surface is smooth and
compact.

Road Implements and Machinery and Their
Use. — Eoad building has been much simplified
and cheapened by the substitution of machinery
for hand labour in transporting material from
place to place. The first advance over the bur-
den bearer was the wheelbarrow. An Ameri-
can engineer in the Philippine Islands tells
of his experience with the native labourer when
the wheelbarrow was introduced there as part
of the regular road-building equipment. As
soon as the barrow was loaded two of the
natives bravely picked it up, carried it to the
point where the material was needed, emptied

102- KOADS, PATHS AND BRIDGES

it and carried it back; the wheel at the end of
the barrow had no significance to them. Mod-
ern practice has made even greater strides
to-day. The wheelbarrow is rarely used now,
except for small jobs or in wet and swampy
places. It has been superseded by some form
of drag scraper drawn by horses.

The complete road-building outfit consists of
a great number of units, which may be roughly
enumerated as ploughs, drag and wheel scrap-
ers, road graders or road machines, disc har-
rows, dump carts, elevating graders, sprinklers,
rollers, crushers with elevators, screens and
bins ; and in the construction of roads of modern
type with bituminous binders a great deal of
special equipment has been devised such as tar
and asphalt spraying machines, and tank-wagon.

Scrapers are intended for use in moving
material after it has been loosened by plough-
ing. They are of two kinds — drag scrapers and
wheel scrapers. The drag scraper is made in
several sizes running from about 3 cubic feet
capacity to a capacity of from 5 to 7 cubic feet.
The average cost is from $6 to $7 each. The
smaller size is designed for one horse and the

THE EAETH EOAD 103

larger sizes for two horses. The drag scraper
is used for moving earth short distances.

The wheel scraper may be described as a
steel box on wheels, open in front, and provided
with levers by which the box may be raised and
lowered and its contents dumped. The capac-
ity is usually from 9 to 16 cubic feet. The cost
should be from $25 to $40.

The elevating grader is provided with a
frame, resting upon four wheels, from which is
suspended a plough and frame carrying a wide
travelling belt. The plough loosens the earth
and casts it upon the inclined belt, which in
turn carries it to the embankment, or to the
wagons, as the case may be. This machine is
particularly adapted for the construction of
earth roads in a prairie country. It cannot be
used to advantage in a very hilly or rocky
country.

The disc harrow is used mainly in the con-
struction of sand-clay roads for the purpose
of thoroughly mixing the sand and clay. Its
use will be explained in the chapter on sand-
clay roads.

The steam roller, the sprinkler and the

104 BOADS, PATHS AND BEIDGES

crusher, with its appliances, are mainly nsed in
the construction of gravel and crushed-stone
roads. It will be described in greater detail
in the appropriate chapters.

For use about the farm and in the treatment
of ordinary earth roads, the plough, the drag
scraper, the wheel scraper and the road ma-
chine are the implements most generally used.
A split-log drag is very simple and exceedingly
useful in the maintenance of earth roads. It
will be described in another chapter.

Under certain conditions the plough is a
most useful implement in road work. When
the soil on the surface of a road is excessively
sandy and the subsoil is of clay, or of gravel
and clay, the road will be greatly benefited by
a deep ploughing. The ploughing brings the
clay from beneath and mixes it with the surface
soil and sand. Thus a sand-clay road is
formed at small expense. On the other hand,
if the road is entirely formed of deep sand, it
will prove a very great mistake to plough up
the road bed unless clay can be added. The
ploughing only deepens the sand and breaks
up what little hard surfacing material has been

THE EAETH EOAD 105

formed on top. Again, if the surface has only,
a little sand or gravel in it, and the subsoil is
practically pure clay, it will prove a great mis-
take to plough it up. To do so would bring an
excess of clay to the surface, and effectually
destroy the surface coating of sand or gravel
or soil. These are apparently very small and
insignificant matters, yet a correct understand-
ing of them, with regard to the principles in-
volved, will enable a road foreman to improve
the roads under his charge.

When ploughing is undertaken, the best
method is to begin in the middle and "back-
furrow" both ways to the middle, thus forming
a crown. After the road has been ploughed,
it may be harrowed and carefully smoothed.
Ploughing should be done in the spring or early
summer. A plough can be used in ditches to
advantage. In excavating there is no better
way to loosen earth than by the use of the
plough. For this purpose there are various
kinds in use. The old-fashioned coulter plough
is effective in breaking up hard gravel or other
material.

When it is necessary to make ditches wide

106 ROADS, PATHS AND BRIDGES

and deep, nothing has yet been devised better
than the ordinary drag scraper. It is service-
able in hauls under seventy-five feet long for
making fills. Frequently a road becomes worn
down and requires widening. The sides may
be ploughed and the earth pulled in with the
scraper. When both sides have to be pulled
in, it is a good plan to make a circular trip,
pulling in the earth from both sides at the same
time. Ditch work may often be handled in this
way and greatly facilitated. Two horses and
two men will handle many times more earth
than could be handled if work was done by hand
with shovels. It is a mistake, however, to at-
tempt to handle material in long hauls with a
drag scraper. The wheel scraper is better
adapted to such hauling, but still should be lim-
ited to about 1,000 feet haul. Furthermore, the
wheel scraper is not well adapted to ditch work,
for the reason that the wheels require a greater
width than is usual in ditches. These scrapers
are better adapted to grading and handling
earth where many cuts and fills are necessary.
As a rule, it does not pay to work less than

THE EAETH EOAD 107

four to six in a run, because an extra team is
necessary to help in loading, and with a less
number of scrapers this team is idle much of
the time.

The road machine is one of the most gener-
ally used of all road implements and scarcely
needs any description. It may be briefly said
to consist of a frame on four wheels, support-
ing an adjustable blade, the front of which
cuts a furrow while the rear end pushes the
earth toward the centre of the road and dis-
tributes it. The work of the grader is superior
to that of the plough and the drag scraper, as
the cut is uniform, whereas the plough cuts
irregularly, and moves material in much larger
quantities and at less cost than can be done by
the drag scrapers. In using the road machine
or road grader, it is best to put not more
than from 4 to 6 inches of loose earth into the
road at one working. The grading should be
done early in the summer when the soil is damp.
The loose earth will then pack and bake; it
will not be so liable to become dusty in sum-
mer, and will have ample time to settle before

108 EOADS, PATHS AND BRIDGES

the rains begin in the fall. This is one of the
most important points in the whole problem of
earth-road construction.

The road machine is on the market in every
conceivable design and varying in size from a
machine suitable for two horses to one capable
of withstanding a traction engine. It is most
useful in crowning and smoothing the road and
for opening ditches. What was said with ref-
erence to the use of the plough is also true in
regard to the use of the road machine. It is
unwise to pull loose sand upon a sandy road,
for to do so is only to make it deeper. On the
other hand, if there is clay in the subsoil under
the sand, it will improve the road to pull it up
with a road machine. It is likewise bad man-
agement to pull clay upon a thin coating of
gravel or soil. The clay will hold water and
make the gravel soften.

It is a great mistake to pull clay from ditches
upon a macadam surface with abroad machine.
For the same reason, it is a mistake to use a
road machine indiscriminately and to pull ma-
terial from the ditches upon a sand-clay or
gravel road. Frequently turf, soil and silt

THE SAND-CLAY ROAD.

1. (Top.) Spreading the clay on the sand. 2. Plowing and mixing
sand and clay. 3. Mixing with the disk-harrow. 4. (Left.) Method,
of laying a road-side drain,.

THE EAKTH EOAD 109

from the bottom of the ditch are piled in the
middle of the road in a sort of ridge, or, if any
effort has been made to spread it, ofttimes it is
done in such a way as to make matters worse.
Material containing grass or other vegetable
matter should never be allowed to be placed on
the road, unless it is a sand road and no clay is
obtainable. Weeds and grass should be burned
or cut and removed before grading is begun.
This simple plan will do much to relieve the
objection often met with in working the road in
the fall, when the ditches are filled with grass.
To pull this mass of weeds and grass and sedi-
ment into piles on the travelled track, besides
making it uneven is the best way possible to
start mudholes.

Another important point in building up a
road with a road machine is to avoid building
up too much at one time. It will be found that
a road built up after using the road machine
a number of times will stand far better than one
built all at once. In the first instance, the ma-
terial is brought up in thin layers and firmly
packed before the next layer is brought up, and
in that way the road is made up of a number of

110 EOADS, PATHS AND BEIDGES

thin layers, each one of which is well puddled
and packed before the succeeding layer is
added. It is too often the case that the road
builder thinks he must have his road high in
the first instance and, consequently, piles up 10
or 12 inches of raw material at one time. The
result is that when the rains come there are no
fewer inches of mud in this newly worked road.
This would not have occurred had the road fore-
man taken more time and built up the road by
degrees.

It is also a common mistake to crown too
high with the road machine. This is particu-
larly noticeable when the road happens to be a
little narrow. For this reason a road to be
worked with a road machine should be of ample
width, not less than 20 feet anywhere, and bet-
ter from 20 to 24 feet wide.

CHAPTER V
THE SAND-CLAY EOAD

A SAND-CLAY road is composed of sand and
clay mixed in such proportions as to form a
compact and firm support to traffic. The per-
fect sand-clay road should be neither sticky nor
sandy. The sand and clay may form a natural
mixture, in which case, the road is termed a
natural sand-clay road. The two materials
may have become mixed in the fields along the
road by successive cultivation of the soil, and
if this soil is used in the construction of a
road, it is known as a top-soil road. There
are many varieties of clay, and consequently a
wide variation in the characteristics of a sand-
clay road. The quality of the sand is a vari-
able factor, as it may range all the way from
fine dust-like particles to coarse grains and
gravel, ' and may be perfectly clean, or mixed
with loam and other material. In consequence
of these wide differences in the materials con-
Ill

112 BOADS, PATHS AND BEIDGES

stituting sand-clay roads, it is impossible to
maintain a uniform standard as to quality of
the road, or the methods of construction.

Properties of Sand. — Sand is, in general,
composed of tiny grains of quartz. While
quartz is one of the hardest minerals known,
it possesses practically no binding or cement-
ing power. The grains of sand, instead of
cohering in a tough mass under the impact of
traffic and the action of water, remain loose and
shifting. Fine sand, when dry, is easily dis-
placed by the wind, which produces in this way
the ever-shifting sand-hills. No road is so
difficult to travel as the road located through
fine sand, and the difficulties are enormously
increased when high winds prevail.

Properties of Clay. — Clay is a decomposition
product of the mineral feldspar. If the clay
has been carried by running water and de-
posited as sediment, it is known as "sedimen-
tary." If the feldspathic rock has disinte-
grated in place, the clay is known as l l residual. ' '
The sedimentary clay is finer grained than the
residual, and is more sticky and plastic. In
contrast with sand, which possesses no binding

THE SAND-CLAY EOAD 113

power, but is very hard, clay is a powerful
binder. It does not, however, possess the qual-
ity of hardness.

It is evident, then, that in the construction
of a sand-clay road the important property in
the clay is its plasticity or tendency to become
sticky and elastic when mixed with water. The
clays which are most plastic are called "ball"
clays. Another important property possessed
by clays in widely varying degrees is the poros-
ity, or capacity for rapid absorption of water.
Clays which possess this quality in the highest
degree fall to pieces under the action of water,
and are called "slaking" clays. It will readily
be seen that the plastic or ball clays will form
a better and more powerful binder for sand-
clay roads than will the slaking clays, but, on
the other hand, they will be much more difficult
to mix, as they disintegrate with far less rapid-
ity.

The shrinkage of clay is an important char-
acteristic in connection with the building of
roads. When water is mixed with clay, expan-
sion results and, when the water evaporates,
the clay contracts. This characteristic of ex-

114 EOADS, PATHS AND BEIDGES

pansion is much more pronounced in some clays
than in others. It must be apparent that the
clays which expand the least are preferable for
road building, as they result in the least dis-
placement of grains of sand, and, consequently,
tend least to destroy the bond between the sand
and clay.

Gumbo or Buckshot Soil. — This is of sedi-
mentary formation and carries a considerable
quantity of organic matter. A large area in
the valley of the Mississippi river and its trib-
utaries is composed of this kind of soil. The
gumbo soil is composed of very fine particles,
the colour of which ranges from grey to black,
according to the amount of organic matter.
Water is readily absorbed and causes the ma-
terial to become exceedingly sticky; when dry,
it breaks up or becomes granulated, which
causes it to be termed "buckshot soil/'

Sedimentary Loam. — In addition to the
gumbo, which contains no sand, there are the
sedimentary loams, which include all classes
between gumbo and clean sand. As the per-
centage of sand increases, the characteristics
of the buckshot soil are less pronounced. The

THE SAND-CLAY EOAD 115

sand prevents granulation of the soil, as well
as marked contraction or expansion. Where
the sedimentary loam contains a large propor-
tion of sand, a reasonably good road can be
made without the addition of other materials.

Mixing of Sand and Clay. — The theory of the
sand-clay road is very similar to that of the
macadam road. In the latter rock-dust and
screenings fill the voids between the angular
fragments of stone and when wet serve as a
cement or binder. The grains of sand may be
likened to the angular fragments of stone and
clay to the rock-dust binder. In the most suc-
cessful sand-clay road just a sufficient amount
of clay is used to fill the voids between the
grains of sand. In this way the sand sustains
the wear, while the clay serves as a binder. If
too much sand is used, the result will be loose
sand on the surface; if too much clay is used,
the surface of the road will become sticky after
rains.

The best mixture of sand and clay can be
made when the materials are wet, and particu-
larly is this true of the plastic or ball clays.
The more water used the better the mixture and,

116 EOADS, PATHS AND BRIDGES

if practicable, the materials should be puddled.
If the road to be treated is sandy, clay should
be hauled upon it, spread as uniformly as pos-
sible, and all large lumps should be broken up.
As soon as a heavy rain has softened the clay, a
few inches of sand should be placed on it and
then a thorough mixture should be brought
about by means of a plough and a disc harrow.
The result will be a successful mixture and a
very disagreeable pasty mud. This condition
will last for only a short time, and the road will
eventually be all the better for it. The extent
to which the mixing should be carried on will
depend largely upon the character of the clay.
If it is a plastic or ball clay, much greater effort
will be necessary to obtain a complete mixture ;
if, on the other hand, it is a slaking clay, the
mixture will be much more readily obtained.
This kind of clay is not as satisfactory, how-
ever, as the ball clay, as its binding powers are
much less. In selecting clay for road purposes,
it is always best to select the stickiest clay
available. A familiar test is to wet the thumb
and place it against a piece of clay. If the
clay sticks to the thumb, it is reasonable to sup-

THE SAND-CLAY EOAD 117

pose that it will stick to the sand; if it will not
stick to the thumb, it is safe to assume that it
will be a poor binder in a sand-clay road.

As the desirable proportions of sand and clay
are such that the particles of clay barely fill the
voids between the grains of sand, it is well, in
determining the quantity of clay to be applied
to a sand road, or sand to be applied to a clay
road, to know approximately how much is
needed. A simple method for determining the
relative quantity is to take two glasses of the
same size and fill one with the dry sand which it
is proposed to use, and the other with water.
The water should then be poured carefully in
the glass of sand, and allowed to trickle down
through the sand until it reaches the bottom of
the glass. When the water has been poured
into the glass of sand to the point of overflow-
ing, we may assume that the voids between the
grains of sand have been filled, and, conse-
quently, the amount of water taken from the
full glass would represent the volume of clay
needed to fill the voids in a volume of sand
equal to that in the other glass. It is better to
use a little more sand than would appear to be

118 EOADS, PATHS AND BBIDGES

necessary, as the tendency is to underestimate
the amount needed. In general practice, clay
is placed on a sandy road to a depth ranging
from 6 to 10 inches, while sand is placed on a
clay road usually to a depth of from 6 to 8
inches.

Construction of a Sand-Clay Road. — The
method of construction depends upon whether
the subsoil consists of sand or of clay. Good
drainage is an essential feature of the sand-
clay road, just as it is of all other types of road.
A sandy or gravelly soil affords better natural
drainage, and if the sand is present to an ex-
ceptional extent, the only provision necessary
for drainage will be to crown the surface of
the road in the same manner as prescribed for
earth roads. If the road is located through
land that is so low as to be continually wet, it
will be necessary, in addition to crowning the
road, to provide wide ditches on each side, and
to raise the roadbed a little higher than the
surrounding ground.

Drainage of a clay subsoil should be provided
in exactly the manner as for earth roads in
Chapter IV.

THE SAND-CLAY EOAD 119

After proper drainage has been secured, the
roadbed should be crowned, beginning near the
source of supply of the clay or sand. The clay
should then be spread to a depth of from 6 to 8
inches in the centre, sloping off gradually to a
thin layer at the sides. Upon the clay should
be placed a thin covering of sand. If the clay
is of the plastic kind, it will then be necessary
to plough and harrow it, taking advantage of
rains to puddle the surface with a disc har-
row. Sand should be gradually added until the
surface of the road ceases to ball and cake.
After the road is completed, if it loosens in dry
weather, more clay should be added. The mix-
ing of the sand and clay may be left to traffic,
but this is an unwise procedure, as it means a
very unsatisfactory road for a long period of
time.

If the clay is placed on sand to a depth of 6
inches, a cubic yard of clay will cover 54 square
feet, consequently, an 18-foot road, treated in
this manner, would require 1 cubic yard of clay
for each 3 feet of length. A mile of 18-foot
road would, therefore, require 1,760 cubic yards
of clay. The amount that can be hauled by the

120 EOADS, PATHS' AND BKIDGES

average team varies from two-thirds to one
cubic yard, according to the character of the
road over which the hauling is done.

If the clay subsoil is to be treated with sand,
it should be ploughed and harrowed to a depth
of about 4 inches. On this prepared subsur-
face should be placed from 6 to 8 inches of clean
sand, spread thickest at the centre and sloping
to the sides, in much the same manner as the
clay is applied to a sand road. These materials
should then be mixed dry instead of wet, which
is preferable when clay is applied to sand. Dry
mixing is preferable because the clay can be
better pulverised when in a dry state. After
the dry mixing has been completed, the
road should be puddled with a harrow after
the first heavy rain. When the materials
are thoroughly mixed and puddled, a road
machine or grader should be used to give the
proper crown to the road. If a horse roller is
available, the road can be improved by the
use of it. As it is impossible to determine
exactly the proportions of sand and clay to be
used in the first place, it is necessary to give
careful attention to the sand-clay road for a

THE SAND-CLAY EOAD 121

considerable time after it is completed, in order
that additional sand or clay may be applied as
needed.

Sand-clay roads have been built in the South
at costs varying from $200 to $1,200 per mile.
This wide variation in cost is due to the dif-
ference in the proximity of sand and clay, cost
of labour, weather conditions, efficiency of
labour, management, etc. Under average con-
ditions a sand-clay road 12 feet in width should
cost from $500 to $600 per mile.

The same considerations which should gov-
ern in the location of earth roads and in the
avoidance of steep grades, apply with equal
force to the sand-clay road.

Sand Roads. — Where roads are composed of
deep sand, and where clay is not available, it
is impossible to make the road satisfactory for
traffic, but it is possible to make at least a slight
improvement.

Dampness is beneficial to a sand road, and it
is well known that wet sand is easier to travel
over than dry sand. Consequently, it is better
to reverse, to a certain extent, the rules of drain-
age which apply to earth and sand-clay roads.

122 EOADS, PATHS AND BEIDGES

The surface of a sandy road should be level and
may even be slightly concave, provided the lon-
gitudinal grade of the road is very slight.
Otherwise, to make a road concave would sim-
ply be to transform it into a ditch, which would
soon be cut into deep gulleys. Fortunately, in
almost all cases, sandy roads are naturally
level.

Shade is injurious to roads composed of clay
or loam, as it prevents the road from drying out.
A sand road, however, should have as much
shade as possible in order to prevent it from
drying out. In order to overcome the shift-
ing, unstable character of the sand, grass should
be encouraged wherever possible. In fact, any
vegetable matter that can be made to grow on
a sand road, or close up to a sand road, is
beneficial. Even if the roots do not spread out
into the travel way, the leaves and twigs from
bushes will fall into the road and aid to a slight
extent in providing a binder. If the road is
sufficiently wide, half of it could be planted in
grass, and traffic could be required to use the
other half; when the grass is mature, traffic

THE SAND-CLAY EOAD 123

could be shifted and the other half planted to
grass. Any vegetable fibre on a sand road is
beneficial, but is of necessity only a temporary
expedient.

CHAPTER VI
THE GEAVEL EOAD

GEAVEL consists of small, partially rounded
fragments of stone produced from larger bodies
of rock through the action of ice or water.

The best gravel beds are found in the Glacial
Drift, which covered Canada and that portion
of the United States north of a line running
from the Atlantic coast a little south of New
York City, in an irregular direction to Cincin-
nati, thence through Topeka, Kans., and north
and west to the Pacific Ocean. The glacial ice-
sheets carried large quantities of stone from the
original rock ledges and ground them to small
pebbles. In general it may be said that this
glacial gravel is found in western Pennsyl-
vania, most of Ohio, northern Indiana, northern
Illinois, and in most of the northwestern States.
The gravel which exists south of the glacial
district, with the exception of river gravel, has
been in most cases produced by a slow disin-
tegration of the rocks in place.

124

THE GRAVEL EOAD 125

Gravel has been extensively used in certain
sections of the South for road building, notably
in Chatham County, Ga., of which Savannah
is the county seat, and Montgomery County,
Ala., while in northern Georgia, Alabama,
Mississippi and Tennessee excellent roads have
been built from abundant chert-gravel deposits.
The gravel deposits in the South, however, are
local and limited in extent, and are confined
principally to the States of Virginia, North and
South Carolina, Tennessee, Georgia, northern
Mississippi, western Kentucky, Alabama and
Arkansas. Texas is well supplied with gravel
in the northeastern portion of the State. The
delta regions of Mississippi and Louisiana are
almost devoid of road-building' materials, and
the gravel deposits are small in quantity and of
inferior quality. Arkansas, as a whole, is not
supplied with good road material, but there are
extensive deposits of gravel in the southwest
portion of the State. In Kentucky the gravel is
limited to local deposits along streams.

Qualities of Gravel. — Eoad-building gravel
should possess three important qualities : hard-
ness, toughness, and cementing or binding

126 BOADS, PATHS AND BRIDGES

power. Of these three qualities the last is
the most important. This binding quality is
due in part to the presence of iron oxide, lime,
or ferruginous clay, and in part to the angu-
lar shape and size of the pebbles composing
the gravel. A good way to determine whether
or not a gravel is suitable for road building is
to notice its position in the pit. If the banks
remain vertical after exposure to the weather,
it is a reasonable inference that the material
possesses a high cementing value and will
cement and compact well in the road. Blue
gravel is universally conceded to be the best
for road construction, because it is usually
derived from trap rocks. As the pebbles com-
posing the gravel retain the characteristics
which they possessed when forming part of the
larger rock masses, it follows that as trap rock
is considered an excellent material for road
building, trap-rock gravel should occupy the
same relative rank among the gravels. Lime-
stone is, generally speaking, a soft rock, and
consequently limestone gravel (which is quite
rare) will usually be found soft and will wear
rapidly. Quartz possesses practically no bind-

THE GEAVEL EOAD 127

ing power, although it is a very hard mineral.
Therefore, gravel which contains an exception-
ally large percentage of quartz will not prove
successful, unless a good binder is added. On
the other hand, the chert gravels, which are
composed mainly of amorphous or non-crys-
talline quartz, possess a very high binding
value.

The shape and size of the pebbles composing
the gravel have an important bearing upon its
value as a road material. In order that the
material may bond readily, the pebbles should
be angular, and should vary in size so that the
smaller fragments may fill the voids between
the larger pieces. The largest pieces of gravel
should not be more than two or two and
one-half inches in their greatest dimensions.
Otherwise, the large fragments will fail to com-
pact and will work to the surface. On the other
hand, the gravel should not be too fine, as in
this case it will be equally difficult to consoli-
date. Many road builders consider the grada-
tion in sizes the most important quality of road-
building gravel.

The angular shape of the gravel is essential,

128 BOADS, PATflS AND BEIDGES

in order that a mechanical bond may be secured.
Gravel obtained from streams is inferior to
pit gravel, for the reason that the constant
action of water has worn the pebbles smooth
and partially round, so that it is very difficult
to obtain the mechanical bond necessary in the
construction of gravel roads; moreover prac-
tically all of the fine binding material has been
removed by the same agency. Even if a fer-
ruginous clay is mixed with the river gravel,
the result is not likely to be as satisfactory as
that obtained by the use of pit gravel.

When the gravel is taken from the pit, it
should not contain more than one-fourth of its
volume in sand or clay. Pit gravel frequently
contains too much clay or earthy matter, while
river gravel may have too much sand. In such
cases, the gravel should be screened so as to
eliminate the material which is too fine and that
which is too coarse. The screens should have
meshes of about 2%, 1% and % inches. Where
gravel is screened in this way, it can be laid in
courses on the road. The fragments which pass
through a 21/2-inch screen may form the bottom
course ; those which pass a 1%-inch screen, the

THREE SORTS OF GOOD ROAD.

1. (Top.) A well-constructed gravel road near Baker City, Oregon.
2. A road surfaced with slag screenings, to which quick lime was
added as an additional cementing agent. 3. A sand-clay road near
Aiken, S. C.

THE GEAVEL EOAD 129

middle course; and the fine material may be
used as the top course, or binder.

Some highway engineers favour the use of
clay as a binder in gravel-road construction,
where the gravel requires the addition of a
binder. The clay should be used very spar-
ingly, however, as it absorbs water and causes
the road to become soft and muddy. When the
clay dries, it contracts and causes the road to
crack. Clay is also affected by frost. Loam is
frequently used as a binder for gravel roads,
and consists of sand and some vegetable mat-
ter, lime, etc., mixed with clay. It possesses
about the same qualities as a clay binder. The
best binder of all is iron oxide, which is fre-
quently found coating the pebbles.

Chert and Chert Gravel. — Chert is a silicious
rock and occurs usually in limestone and sand-
stone formations. It is generally believed to
be formed by a chemical precipitation from sea
water. The material is found sometimes com-
pletely covering the ground; sometimes in the
beds of streams and narrow valleys where it
has been redeposited by the action of water;
and in other cases in banks and pockets on hill

130 EOADS, PATHS AND BBIDGES

and mountain sides. Bank cherts usually occur
in nodular masses, but where they are found in
stream beds they are often broken into angular
fragments, varying in size from 1 to 6 inches.
Bank cherts are easily quarried by blasting and
the lumps reduced to proper size by napping
hammers or by rolling.

Where these materials are found in the beds
of streams they are commonly called gravel.
Creek gravel formed from chert is usually of
uniform size and comparatively clean, while the
bank gravel often contains earthy matter and
fine particles of the same material. The creek
gravel wears the best, but it does not bind as
readily, or form as smooth a surface as the bank
deposits. Where both creek and bank cherts
are available, good results can be obtained by
using the former for foundation and the latter
for the wearing or binding course. A road
built in this way at Florence, Ala., under the
direction of an expert of the Office of Public
Eoads, in 1898, is said to be in perfect condi-
tion at the present time, although it has never
been resurfaced. Chert is found in the south-
ern portion of the Appalachian Mountains,

THE GEAVEL EOAD 131

along the Ozark foothills, in southern Illinois,
southern Missouri, northern Arkansas and
eastern Oklahoma.

Gravel-road Construction. — The first step in
the construction of a gravel road is to obtain
the desired grade, after which the road should
be given a suitable cross-section, or crown, so
that the centre of the finished roadway will be
from 6 to 8 inches higher than the edge of the
gravelled portion for a 16-foot road. About
the same ratio of height to width should be
maintained for other widths than 16 feet. The
subgrade should be thoroughly rolled and com-
pacted, and all loose and unstable earth removed
and replaced by sand and gravel. The gravel
should then be placed on the subgrade to a total
depth of from 8 to 12 inches in the centre, taper-
ing off to a depth of from 4 to 6 inches on the
sides.

Sometimes it is advisable to screen the gravel
and place it in layers, and the coarser should be
used for the foundation, as previously ex-
plained. The thickness of the respective
courses should be approximately from 4 to 6
inches for the foundation course, from 3 to 4

132 BOADS, PATHS AND BEIDGES

inches for the second course, and from 1 to 2
inches for the surface, or binding course.
Each layer should be thoroughly sprinkled and
rolled with a roller weighing not less than 2 tons,
and at least 2% feet long. If a roller and sprin-
kler are not available, the road should be con-
structed in the spring, as the successive rains
will cause the material to pack much better than
if the road were built in the dry, hot summer or
early fall. This is an exceedingly important
point and one which is generally overlooked.
If the gravel fails to compact, a thin layer of
crushed-rock screenings applied to the surface
will be found exceedingly beneficial.

McAdam condemns the practice of dumping
gravel indiscriminately on the road and leaving
it for traffic to compact. The following quota-
tion taken from his report, published in 1824,
applies with equal force to present-day condi-
tions.

"The formation of roads is defective in most parts
of the county; in particular the roads around Lon-
don are made high hi the middle, in the form of a
roof, by which means a carriage goes upon a danger-
ous slope, unless kept on the very centre of the road.

CONSTRUCTING A MACADAM ROAD.

The three courses of stone are shown in relative size : the largest
("No. Is") at the bottom; the second, smaller (''No. 2s1'), and the
top or binder course of screenings; also a view of a road, showing its
foundation, rolled, and a first course applied.

THE GRAVEL EOAD 133

" These roads are repaired by throwing a large
quantity of unprepared gravel in the middle, and
trusting that, by its never consolidating, it will in
due time move towards the sides.'*

The principal causes of failure in gravel-road
construction may be summarised as follows :

1. Poor material.

2. Spreading the gravel in dry weather; dumping
it in heaps and leaving it for traffic to compact.

3. Placing the gravel on surfaces filled with ruts
and holes.

4. Insecure or poorly drained foundation.

5. Improper construction of ditches or culverts.

6. Making the road so narrow that wagons will
track, thereby forming deep ruts.

7. Failure to fill ruts and holes with gravel.

The information given in Chapter IV regard-
ing drainage applies with equal force in the con-
struction of gravel roads, and should be fol-
lowed faithfully, as otherwise a poor road will
result, even if the greatest care is used in the
selection of materials and in placing them upon
the subgrade.

CHAPTER VII
THE BEOKEN-STONE ROAD

THE term " macadam " is generally under-
stood to mean a particular type of road. That
this type of construction is different from that
used by John L. McAdam, and named after
him, need cause but passing comment. Mod-
ern machinery and modern science have worked
many changes, but the fundamental principles
demonstrated by McAdam, that the foundation
must be well drained in order properly to carry
the loads which come upon the road; and that
an aggregate of broken stone can be made to
cement, or knit together, so as to be waterproof
and firm enough to support traffic, still holds
good. McAdam 's own explanation of his
method is clear, concise and to the point. In
his report, published in 1824, he said :

"The roads can never be rendered thus perfectly
secure until the following principles be fully under-

134

THE BROKEN-STONE EOAD 135

stood, admitted, and acted upon: namely, that it is
the native soil which really supports the weight of
traffic; that while it is preserved in a dry state, it
will carry any weight without sinking, and that it
does in fact carry the road and the carriages also;
that this native soil must previously be made quite
dry, and a covering impenetrable to rain, must then
be placed over it, to preserve it in that dry state;
that the thickness of a road should only be regulated
by the quantity of material necessary to form such
impervious covering, and never by any reference to
its own power of carrying weight. The erroneous
opinion so long acted upon, and so tenaciously ad-
hered to, that by placing a large quantity of stone
under the roads, a remedy will be found for the sink-
ing into wet clay, or other soft soils, or in other words,
that a road may be made sufficiently strong, arti-
ficially, to carry heavy carriages, though the subsoil
be in a wet state, and by such means to avert the
inconveniences of the natural soil receiving water
from rain, or other means, has produced most of the
defects of the roads of Great Britain. . , .

" Every road is to be made of broken stone with-
out mixture of earth, clay, chalk, or any other matter
that will imbibe water, and be affected with frost;
nothing is to be laid on the clean stone on pretence of
binding; broken stone will combine by its own angles
into a smooth, solid surface that can not be affected
by vicissitudes of weather, or displaced by the action
of wheels, which will pass over it without a jolt, and
consequently without in jury. "

136 EOADS, PATHS AND BEIDGES

In addition to the modifications due to prog-
ress, other modifications of a local character
must be made because of climate, topography,
nature of traffic, character of the local stone,
etc. Thus, while we can specify the construc-
tion for any given road to the smallest detail,
it must always be borne in mind that different
conditions necessarily demand changes, at least
in the minor details. Furthermore, a proper
recognition and appreciation of these details
will invariably save money for the taxpayer.

While the macadam, or broken-stone, type of
road is particularly well adapted to those carry-
ing a moderate traffic, it is not economical as a
pavement for city streets carrying heavy traffic,
or on roads subjected to heavy automobile
traffic, unless some special type of binder other
than the stone dust is used. In some ways a
macadam road resembles quite closely a well-
built gravel road, but, as a rule, it will stand
heavier traffic and wear better, since the me-
chanical bond between the aggregates is
stronger than that which can be supplied by
the more or less rounded pebbles of the gravel.
Even in regions where gravel is abundant, a

THE BEOKEN-STONE EOAD 137

macadam surfacing may prove more econom-
ical on the more heavily trafficked sections
where the gravel does not furnish a sufficiently
strong bond to withstand the requirements of
the traffic.

Width of Surfacing. — Experience has shown
that for ordinary country roads the macadam
surface need not be more than from 13 to 16
feet wide, if suitable earth shoulders are built
on each side. Thirteen feet allows two vehicles
to pass each other safely. Sixteen feet is more
satisfactory, especially when more or less frac-
tious teams are passing automobiles. If the
stone is less than 13 feet wide, there is a like-
lihood that the edges of the macadam will be
sheared off by the wheels, unless the shoulders
are made of especially good material. In fact,
a width of less than 13 feet is of doubtful value,
unless the surface portion is reduced to the very
narrow width of 8 or 9 feet. This serves fairly
well as a single track, where the prevailing
loaded traffic is in one direction, and a good
earth road is provided on one or both sides of
the macadam.

There are many communities where during

138 EOADS, PATHS AND BEIDGES

the greater part of the year a well-kept earth
road is about all that is desired, but when, for
the few months during the winter or spring,
these earth roads become all but impassable.
Here a narrow strip of macadam with a well-
kept earth road on one or both sides will some-
times answer the purpose at a much lower cost
than a standard-width road of from 13 to 15
feet; for, during good weather, practically all
the traffic, excepting the very heavy loads, will
use the more resilient earth road, while during
bad weather all will use the macadam as far as
possible. The light traffic will turn out on the
earth road to pass the loaded teams. What-
ever may be the width of the stone, however, the
shoulders should be firm enough to permit occa-
sional passage of wheels.

In the past years it was almost the universal
practice to build the macadam roads very thick.
Of course, this required a very large amount
of material, and made the cost extremely high.
A comparatively few years ago, roads less than
eight inches thick were rarely heard of, and not
infrequently a thickness of at least 12 inches of
macadam was thought to be necessary for a

THE BEOKEN-STONE EOAD 139

good road. To-day one of the most conspicuous
means of reducing the cost has been by decreas-
ing the thickness of the surfacing, and we find
many roads supporting quite heavy traffic,
although only 5 or 6 inches in thickness. Four
inches of macadam after rolling is about the
least thickness which is practicable, and, except
in unusual cases, a depth greater than 8 inches
after rolling is unnecessary.

A macadam surfacing should be hard, smooth
and impervious to water. Much attention must
also be given to the foundation, which should
be firm and sufficiently strong to sustain any
load likely to come on the road at any time of
the year.

Quarrying for Material. — In opening a new
quarry careful attention should be given to the
inclination of bed joints or seams, which, for
economical quarrying, should be parallel with
and dip toward the working face of the ledge.
The drainage of the quarry should also be con-
sidered and the floor level should, wherever pos-
sible, be so arranged that the water can be
drained from the working face by gravity.
Wherever possible the ledge should be opened

140 EOADS, PATHS AND BEIDGES

where the overburden is light and where but
little expensive stripping will be necessary. The
quarry should be located, if possible, in such a
position that gravity will assist in handling
materials, so that tram-cars may carry material
from the floor of the quarry to the mouth of the
crusher by gravity. The loaded car in its down-
ward trip may be made to drag the empty car
back to the floor of the quarry. If the quarry
is located in a pit it will be necessary to provide
power for this purpose ; furthermore, a consid-
erable expenditure for pumping water will be
entailed, aside from that necessary for opera-
ting tramways by mechanical power.

In removing the overburden the earth should
be carried far enough away from the quarry
not to interfere with future operations. When
the overburden is of a tenacious nature, or when
it is frozen, it may be loosened by sinking a
few holes from two to five feet in depth and by
charging them with explosives. Low grade
dynamite is suitable for this purpose. If the
overburden consists of earth or gravel, it can
sometimes be removed economically by the use
of water and a flume.

BAD ROAD-COXSTRUCTIOX.

1. (Top.) Loose stone thrown on and left to be packed by traffic
2. Raveling of macadam caused by use of stone which has little bind-
ing power. 3. Result of the use of quartz, lacking binding power;
also, evidence of a bad foundation and poor drainage.

THE BKOKEN-STONE EOAD 141

As road-building rocks are usually hard and
tough, the drill-holes in the quarry face can be
more economically placed by means of steam
or compressed-air drills than by the use of hand
drills. For gravels, cherts and various other
soft materials used in road building, hand or
churn drills may, however, be used to advan-
tage. If a steam drill is employed, the steam
may be procured from the boiler which operates
the crushing plant and be conveyed to the
drilling machine by small iron pipes. The
quarryman should use good judgment in the
selection of the positions where the holes are
to be bored. He should consider the effects of
the action of the explosive on the rock before
him, and the relation of the bore-holes to the
face of the quarry. In this connexion it is
necessary that he examine carefully the fis-
sures in the rock before the holes are drilled.
To get the best results the rock should present
an unsupported face on every side, but in ordi-
nary practice this condition seldom obtains.
The wall of the quarry is usually vertical, and
the two free faces are the top and the breast of
the rock. Ordinarily, therefore, the bore-holes

142 BOADS, PATHS AND BEIDGES

should be placed as nearly parallel to the longest
free face of the rock as possible.

The object in quarrying rock for road build-
ing is to shatter the materials as much as pos-
sible, and for this reason high explosives are
preferred. Dynamite is a rapid and violent
explosive, and produces effects very suddenly.
It is, therefore, better adapted than giant
powder for quarrying rock for road building.
Dynamite dislodges the rock and, if properly
used, reduces most of it to a size suitable for the
crusher without sledging ; consequently, the cost
of quarrying with high explosives is cheaper
than with low explosives. If giant powder is
used, it is necessary either to make larger bore-
holes qr to increase the number to obtain the
same results.

It may be noted in this connexion that any ex-
plosive containing nitro-glycerin is commonly called
dynamite. Dynamite is usually made by partly satu-
rating some porous material with nitro-glycerin. The
percentage of nitro-glycerin usually contained in
dynamite varies from 40 to 75. If by the use of the
40 per cent, dynamite it is found that the rocks are
blown out in chunks too large for the crusher, then it
is advisable to use the 75 per cent, nitro-glycerin. A

THE BKOKEN-STONE EOAD 143

few experimental shots with dynamite of different
grades will indicate the percentage which can best be
employed in any particular quarry.

Crushing. — A crusher for road building
should be provided with a suitable elevator and
with screens for separating the materials into
their proper sizes. Eevolving screens for small
plants are usually about 10 feet long, 32 inches
in diameter, and should revolve at the rate of
about 20 revolutions per minute. The screen
is divided into sections, and the lengths of each
one and the sizes of holes for diabase and other
harder rocks should be about as follows : First
section, 3% feet long, holes % inch in diameter;
second section, 3 feet long, holes 1% inches in
diameter; and third section, 3 feet long, holes 3
inches in diameter. No hard stone larger in
diameter than will pass through the 3-inch holes
in the screen should be used in a macadam road,
and, therefore, stones too large to go through
the larger holes should be returned to the
crusher by gravity or by means of a belt con-
veyor, where they are recrushed. If the tail-
ings are not recrushed, then they should be
eliminated from the work. For limestones and

144 KOADS, PATHS AND BRIDGES

the softer varieties of rock the size of holes in
the first and second sections of the screen may
be increased to % inch and 2 inches, respec-
tively. A portion of the screen which contains
the %-inch holes should be provided with a dust
jacket, as the softer rocks usually produce more
dust than is necessary for binding material.
The jaws of the crusher should be so set as to
make as few tailings as possible, and the lengths
of the screen sections should be adjusted to the
same purpose.

For receiving the various sizes of crushed
rocks, bins with slanting metal bottoms and
sliding doors should be provided, so that the
material can be loaded into wagons by gravity.
Partitions should be built in the bins so as to
keep the differently sized materials separated.

Two types of crushers are now commonly used in
crushing rock for road building. One is the jaw type
of crusher, generally used for small portable plants.
In this machine one of the jaws moves backward and
forward by means of a toggle joint and an eccentric,
and the stone descends as the jaw recedes. As it re-
turns, it catches the stone and crushes it. The maxi-
mum size of the products is determined by the dis-
tance the jaw plates are apart at the lower edge.

ROAD-MAKING MACHINERY.

1. Rolling the second course of macadam. 2. A portable stone
crusher. 3. A spreader.

THE BROKEN-STONE ROAD 145

The gyratory crusher consists of a solid conical steel
shaft supported by a heavy mass of iron somewhat
like an inverted bell. By means of an eccentric, the
rotary motion given to the shaft is such that every
point of its surface is successively brought near the
surface of the "bell," and the rock caught between
the shaft and the bell is crushed. The gyratory
crusher will not produce as many flat pieces or tail-
ings as the jaw crusher, because the stones have to
come in contact with two curved surfaces at the same
time before they are broken. It is peculiarly
adapted, therefore, to crushing rocks which are more
or less laminated.

Large stationary plants are, as a rule, desirable
only where the broken stone must be shipped by rail.
There are several portable plants on the market
which may be bought at prices ranging from about
$1,500 to $2,500, and which are well adapted for
country use. The complete plant includes stone
crusher and engine boiler, portable bins, revolving
screens and an elevator for lifting the broken stone
from the discharge of the crusher into the screen.
These outfits are mounted on wheels, so as to be
readily moved from place to place. Where no special
difficulties are encountered in setting up the plant,
it may be moved from one place to another at a cost
of from $50 to $100. The average output of such a
plant as has been mentioned is from 75 to 100 cubic
yards every day. The amount of the output, how-
ever, will depend very largely on the character of the
stone which is being crushed, and the ability of the

146 EOADS, PATHS' AND BEIDGES

man who has the plant in charge. The hard usage
to which the crusher is subjected naturally entails
much repair work, and requires constant and skilful
attention in order to secure the best results. Where
there is a choice as to the location of the crusher, it
should be placed at about the middle of the stretch
of road to be built, so that the output can be hauled
in both directions. The distance which the broken
stone can economically be hauled will generally not
exceed over one mile. This would tend to show that
unless other conditions are involved, two miles of
road is about all that can be economically constructed
from each setting of the crusher. In general it will
also be found advisable to set the crusher at the
quarry and haul the crushed stone to the road, rather
than to set the crusher at the road and haul the quar-
ried stone to the crusher.

Every effort should be made to reduce the
number of times which the rock must be han-
dled. By setting the crusher at the quarry, the
tram-cars can often be rigged so as to be ope-
rated, either by cable with the power supplied
by the crusher engine, or by gravity, and the
stone conveyed direct from the ledge and
dumped on the crusher platform. With this
arrangement, moving the stone will require the
minimum amount of hand labour.

In some places, it may be found more econom-

THE BKOKEN-STONE EOAD 147

ical to have the stone shipped in from some per-
manent crushing plant than to purchase a
crushing outfit ; and this feature should be care-
fully considered. It is well to study the char-
acter of the local stone, to ascertain whether it
is such as to justify its use, or whether it would
not be more economical to import a better stone,
at least for the surface course.

Road-Building Machinery. — A roller oper-
ated by mechanical power has almost entirely
superseded the old-fashioned horse roller. Its
weight is an important consideration for two
reasons : First, the cost of the roller is approx-
imately so many dollars per ton ; second, exist-
ing bridges and culverts are rarely strong
enough to carry the heaviest rollers. For coun-
try roads, experience has demonstrated that a
10-ton roller is sufficiently heavy. There are a
number of excellent makes of such rollers on
the market, which may be had at prices ranging
from about $2,000 to $3,500.

Another essential in the construction of a
macadam road is the sprinkler. A sprinkler
with a capacity of from 450 to 600 gallons is
usually sufficient. Local conditions such as

148 EOADS, PATHS AND BEIDGES

grades and the distance that water must be
hauled will determine the proper size. The
sprinkler should be provided with extremely
broad tires, to assist in rolling the partially con-
solidated macadam, rather than to loosen it or
to form ruts.

The road machine, or grader, is a most valu-
able implement, and one which is often over-
looked. All too often its only use, or rather
misuse, is that of scraping back upon the road
the worn-out material which has been washed
into the gutters. The road machine can and
should be used to good advantage in shaping the
road preparatory to the application of the
broken stone. It is not uncommon to find that
with a skilled operator the entire subgrade can
be shaped with the road machine, thus doing
away with considerable hand labour.

Where a large amount of road building is
done automatic spreading wagons will prove
economical, but since such wagons can, as a
rule, be used for no other purpose, they would
prove a financial burden to a contractor or a
municipality that was doing but a small amount
of road building.

THE BEOKEN-STONE KOAD 149

Weight of Broken Stone. — Broken stone is
frequently sold by weight. Before estimating
the cost of a road, when a stone is to be paid
for thus, the road officials must know how much
the stone will weigh per cubic yard. The erro-
neous impression that all stone weighs the same
per unit volume is quite general throughout the
United States. One often hears it stated that
a cubic yard of broken stone weighs a ton and
one-third, regardless of the kind of stone. The
following table taken from Farmers' Bulletin
No. 338, United States Department of Agricul-
ture, gives the specific gravity and weight of a
number of the more common rocks :

SPECIFIC GEAVITY AND WEIGHT OF VARIOUS
EOCKS.

Number of
samples tested.

Name.

Specific
gravity.

Weight per
cubic foot of
solid rock.

Weight1 per
cubic yard of
solid rock.

;

Max.

Min.

Av.

&
J

•Q

•j

,Q
»3

3
124
33
60
11
53
358
106

Peridotite (trap).
Diabase (trap). . .
Diorite (trap) . . .
Schist .

3.55
3.20
3.35
3.20
2.80
3.10
3.10
3.00

3.25
2.60
2.70
2.65
2.50
2.50
2.00
2.00

3.40
2.95
2.85
2.90
2.65
2.70
2.65
2.65

221
200
209
200
175
193
193
187

203
162
168
165
156
156
125
125

212
184
178
181
165
168
165
165

2,984
2,700
2,821
2,700
2,362
2,605
2,605
2,524

2,741
2,187
2,268
2,227
2,106
2,106
1,687
1,687

2,862
2,484
2,403
2,443
2,227
2,268
2,227
2,2277

Felsite

Quartzite

Limestone

1 Tons of 2,000 pounds.

150 KOADS, PATHS AND BBIDGES

The above table gives the weights of the solid
rock as it is found in the quarry. If it is
assumed that the volume of the stone, after it is
crushed and lies in the bins, has a void of 50 per
cent., and the average weight of peridotite is
compared with the average weight of granite, it
will be seen that the crushed peridotite weighs
1.43 tons to the cubic yard, while the granite
weighs only 1.11 tons. The heaviest diorite
weighs 1.41 tons to the cubic yard, and the light-
est only 1.13 tons. Differences as marked as
these emphasize the great need of careful deter-
mination of the weight of the material before
any contracts are let.

When broken stone is purchased by measure-
ment, from cars or in wagons, the specifications
should always state where the measurements
are to take place. It is evident that the stone
will occupy considerably more space when it is
first loaded into either the car or the wagon
than after it has been jolted about in transpor-
tation, either by rail or on the wagon road.

Earth Work. — No earth work should be un-
dertaken until the grades have been definitely
established and the grade stakes set. Such

THE BEOKEN-STONE EOAD 151

work of course belongs to the engineer, and
this holds true whether it be in regard to the
construction of a new road or the reconstruction
of an old one. In fixing the grades, care should
be taken to adjust the cuts and fills so that there
will be no undue amount of waste or borrow as
explained in Chapter IV. No extreme refine-
ment, such as is sometimes practised on railroad
work in balancing the cuts and fills, is necessary
in highway construction. In most States, the
right of way provided is wider than the width
necessary for the roadway. Therefore, where
more fill is needed, the additional material can
readily be secured by simply widening the adja-
cent cut to the desired extent, and, where the
cuts are in excess, convenient wastage can read-
ily be found, by simply widening the adjacent
fills. This does not mean, however, that the
work is to be done in a haphazard manner, but
that the computations and surveys shall be
carefully made and where additional widenings
are needed they shall be immediately staked out
on the ground.

It is obvious that the subgrade, or foundation,
of a road is the part most nearly permanent.

152 BOADS, PATHS LiND BEIDGES

The grades should, therefore, be studied most
carefully, since they cannot be changed without
great expense.

Drainage. — Drainage is absolutely essential
to macadam, as well as to any other form of
road. The road should be so constructed that
it will shed the water to the side ditches as rap-
idly as possible, and the side ditches in turn
must be of such size and slope as to remove the
water from the road quickly and completely.
For a narrow macadam road, a crown or side
slope of % of an inch to the foot for the mac-
adam portion will be about right. For a wide
road this will give too much crown, and the
side slope must be reduced to % or perhaps %
inch per foot. The slope of the shoulders
should be equal to, or perhaps in general, a
little greater than that of the macadam. The
slope of the side ditches must be made to vary
somewhat with local conditions. If possible the
slope should be sufficient, so that the ditches
will be self-cleansing, and not have a tendency
to fill with detritus washed from the road.
On the other hand, the slope should not be so
great as to cause erosion. Where steep grades

THE BEOKEN-STONE EOAD 153

cannot be avoided, the gutters or side ditches
must be either paved, or else stops placed at
occasional intervals to check the velocity of the
water. Nor should the practice, which is so
often found, of carrying the water along the
road for long distances, be tolerated. Water
is always an element of danger to a road, and
should be gotten rid of as quickly as possible.
Every outlet should be utilised for this purpose,
even though it involves the construction of a
few more cross-drains.

Surface water is not the only danger to a
macadam road. In many places special atten-
tion must also be given to the underground
waters. It is sometimes possible to drain the
road with open side ditches, but deep ditches
on the roadside are an element of danger, and,
where the ground waters are to be removed
from the road, it will usually be preferable to
employ tile drains. Sometimes the direction
of the movement of the underground water is
such that a single drain on one side of the road
will be sufficient. In other cases, a drain will
be required on both sides. The best practice in
road drainage is to remove the ground water

154 KOADS, PATHS AND BEIDGES

to such a depth that there will be no danger
from the heaving action of the winter frosts.
The drains usually consist of narrow trenches
filled more or less completely with broken stone
or gravel, and having a drain tile near the bot-
tom. The tile used is ordinarily the open-joint
drain tile, which must be laid true to grade, and
provided with free outlet. Sometimes the pipe
is omitted and the trench is filled entirely with
stone, when it is called a blind drain. This
practice, however, is not to be recommended
where large quantities of water need to be re-
moved at any time during the year.

Cross-drains may be made of concrete, or, if
not large, iron pipe or vitrified clay tiles may be
used. Eecent improvements in the manufac-
ture of non-corrosive steel have made that
material available for this purpose. Vitrified
clay tile has also been used, as well as abused,
to a large extent in past years. It should
never be laid close to the road surface, nor
where there is the least danger of the drain
ever clogging in cold, winter weather. Many
failures of clay tile have been caused in the
northwestern States by a winter thaw during

THE BEOKEN-STONE EOAD 155

which the tiles become clogged with slush, ice
and water, and then this thaw is followed by a
freeze, which, of course, bursts the tile. Of all
materials at present, concrete seems the most
durable, as well as, in the majority of cases, the
most economical. Where large bridges or cul-
verts are required, detailed designs should al-
ways be made before construction.

Subgrade of Macadam. — The surface upon
which the broken stone is to be placed must be
hard, smooth and carefully crowned. This is
necessary to prevent excessive use of stone on
the one hand, or the undue waste of stone on the
other. If the foundation is not hard and firm,
the stone will be pressed into it by the roller>
and thus wasted. If it is not properly crowned,
an unnecessary quantity of stone will be re-
quired. When macadam is to be of uniform
thickness throughout its cross-section, the crown
of the subgrade must be the same as that of the
finished roadway. If the macadam is to be
thicker at the centre than at the sides, a part
of the crown will be of the macadam itself, and
the centre of the subgrade should be raised only
enough to produce the surface crown when the

156 EOADS, PATHS AND BEIDGES

stone is in place. As has already been stated,
the road machine is a most useful implement in
shaping the subgrade.

After the roadbed is shaped to the approxi-
mate cross-section, it should be rolled until it
is hard, firm and smooth. If soft places are
found, or if depressions develop during the roll-
ing, these should be filled with good material,
and then further consolidated with the roller
until the subgrade has the required cross-sec-
tion as nearly as practicable.

Placing the Stone. — The stone should be
placed in courses not to exceed 6 inches in
depth when loose, as this is about the greatest
depth which can be thoroughly consolidated
with a roller. On the prepared subgrade, which
has been properly rolled and consolidated, is
spread the first course of stone, usually varying
in size from l1/^ inches to 3 inches in the largest
dimensions. Much larger stone than this
should not be used in the foundation unless the
road is to be very thick. In practice two meth-
ods are used for spreading broken stone. One
is to dump the stone on a board platform and
then shovel it into place on the road. The other

THE BBOKEN-STONE EOAD 157

is to use either an automatic spreader, or else
dump the load directly on the roadway and
simply spread it by pushing a portion of the
stone in the different directions, or until the
required thickness of loose stone is obtained.
When the stone is spread by simply raking off
the top of the loads dumped directly on the
roadway, the proper consolidation is not secured
by rolling; the stone will be denser and more
compact where the load is dropped. An uneven
roadway sometimes results, and in some ex-
treme cases the position of each load can be
clearly seen after the road has been in use for
some time. To obtain the best results each
load of stone should be dumped in three or four
piles. This facilitates the spreading and in-
sures a more uniform distribution of the
material.

When about 100 feet or so of the first course
have been spread, the rolling should begin. The
roller should commence on the outer edge of
the macadam with the outer wheel well up on
the shoulder, and gradually work towards the
centre of the roadway. When the centre has
been reached, the road should be crossed over,

158 BOADS, PATHS AND BRIDGES

and the other side rolled in the same manner
as the first. After both sides of the roadway
are moderately firm, the roller should be moved
gradually towards the centre, until the entire
lower course is thoroughly compacted. Where
the foundation is poor, or a bad silt soil is
encountered, it is well to use a filler in the bot-
tom course. This should consist preferably of
a good dry sand which is spread over the stone
after it has been rolled fairly well. The rolling
is then continued until the voids have been
forced completely full of sand or stone screen-
ings. No clay, loam or perishable foreign ma-
terial should be allowed in the filler. Not only
will a filler prevent a slippery clay from work-
ing up into the interstices of the stone, but it
will also assist in consolidating a stone which
does not possess good mechanical bonding quali-
ties, such as quartzite.

If depressions develop as a result of the roll-
ing, additional stone of the same size used in
the course should be added and the rolling con-
tinued, so that before the second course is
applied the lower course is smooth and true to
cross-section.

THE BEOKEN-STONE EOAD 159

After about 100 feet of the first course of
stone is rolled, the second course, consisting of
stones varying in size from 1% inches down to
% inch, is spread and rolled in the same manner
as the lower course. The thickness of the sec-
ond course usually varies from two to four
inches compacted. The stone should be care-
fully spread and considerable vigilance is nec-
essary if the spreaders are not accustomed to
their work, in order to prevent the surface hav-
ing a wavy appearance when the rolling is com-
pleted. It is quite a temptation with the
workmen to fill these small depressions with
screenings rather than with the stones of the
proper size.

When the surface is thoroughly compacted,
which is usually judged by the absence of any
wavy motion in front of the roller, the screen-
ings or binder course is applied. Only suffi-
cient screenings should be applied to fill the
voids in the stone and form a very slight
covering on the surface. Screenings should be
spread in successive thin coats with alternate
rolling. Sometimes it is a good plan to pass
the roller once or twice over the screenings

160 ROADS, PATHS AND BEIDGES

as they have been spread on the roadway while
they are dry. The sprinkler is then put on in
advance of the roller, and as much as possible
of this dust of the screenings is flushed into the
crevices of the stones. The sprinkling and roll-
ing should continue until the surface puddles,
showing that the voids are substantially filled.
The process of binding the top course is the
most critical one of the entire job. The ability
of the roller operator is a very important factor
in macadam work. The appearance of the road
surface depends to a large extent on his skill.
As soon as the road has been puddled, it
should be allowed to dry a few days, and may
then be opened to traffic. In fact, if a road can
be opened in sections as completed, it is more
preferable than to wait until the entire road is
done, and then throw it open. Where it is
opened in sections, it will be found possible at
times to run back over it with the sprinkler and
roller. Traffic on a green road always produces
more or less roughness or7 even ravelling, so that
permitting travel on the road while it can still
occasionally be reached with the roller, is one

THE BEOKEN-STONE EOAD 161

of the most rapid ways of obtaining the final
set to the road.

On a very clayey or silty soil considerable
care must be exercised in order to prevent the
water from reaching the subgrade in quanti-
ties sufficient to soften it. If much water
reaches the subgrade, there is great danger that
the clay will be forced up into the stone, and
depressions will result, and the undesirable clay
will penetrate into the stones.

Cost of Macadam. — No formula has yet been
devised whereby the cost of macadam roads can
be computed for any locality without a detailed
survey and close examination of conditions.
There are too many uncertain factors which
enter into the construction of the road in such
varying proportions to make a table of cost
of macadam roads of any great practical value.
Each road is a problem in itself, and while one
mile of road may cost a given amount, the
adjoining mile may often cost twice as much,
for no other reason than the variation of neces-
sary factors. Eoughly, it may be stated that in
various parts of the United States the cost of

162 BOADS, PATHS AND BEIDGES

macadam roads, having a width of 15 feet and
a thickness of seven or eight inches, ranges
from $2,000 to $10,000 per mile.

CHAPTER VIII

SELECTION OF MATERIALS FOR MAC-
ADAM ROADS

IT is impossible to construct a satisfactory
macadam road with inferior materials. If a
very soft rock is used, the road will wear rapidly
and soon have to be renewed. If the rock does
not possess sufficient binding power and no ade-
quate binder is used, it will not consolidate, and
the road will soon go to pieces. Enormous
sums of money have been wasted through the
use of unsuitable materials, and there are many
examples of unnecessary expense through the
use of material brought from a long distance
when one locally available would have answered
the purpose equally well.

It has been found that, in a general way,
certain classes and types of rock are more suit-
able than others for road building. For
example, trap rock is considered to be an
excellent material for macadam roads, while

163

164 BOADS, PATHS AND BBIDGES

quartzite is of very little value except in the
foundation. Unfortunately, the trap stones
are not common to all sections of the United
States. Some of the fine-grained granites
usually give good results, as do the felsites,
some of the harder limestones and the dolo-
mites.

In general the micaceous, schistose and meta-
morphic rocks have but little value as sur-
facing material. Sometimes, however, the
harder of these may be used for the lower
course of the macadam, while the upper
course is built of a better grade of stone.
Some of the coarsely crystalline granites and
some of the limestones, if very soft or if crys-
talline to any extent, are of very little value.
On the other hand, however, there are instances
recorded where certain schistose rocks have
been used with excellent results. The following
table gives in compact form the classification
of all rocks used in the construction of macadam
roads :

SELECTION OF MATERIALS 165

GENEKAL CLASSIFICATION OF KOCKS.

Class. Type.

Family.

f a. Granite

r ^ Intrusive

I b. Syenite

(plutonic)

d. Gabbro

I Igneous -

Le. Peridotite

fa. Rhyolite

2 Extrusive

J b. Trachyte

(volcanic)

* " * ' "i c. Andesite
d. Basalt and dia-

L base

11 Calcareous

( a. Limestone

II. Sedimentary . . J
[2. Siliceous . .

\ b. Dolomite

{a. Shale
b. Sandstone
c. Chert (flint)

11. Foliated . .

{a. Gneiss
b. Schist

c. Amphibolite

{a. Slate

2. Nonfoliated.

b. Quartzite
c. Eclogite
d. Marble

Igneous or fire-formed rocks are those which
at one time have been in a molten state and have
solidified, either underground or on the earth's
surface. Heat, pressure, and the chemical
composition of the rock, together with the pres-
ence of vapours, were the causes which gov-
erned the final structure of the material.
Those rocks which were consolidated deep
underground are known as plutonic and are
formed of coarse crystals. Examples of plu-
tonic rocks are granite, syenite, and diorite.

166 BOADS, PATHS AND BEIDGES

The rocks which have solidified at the surface
include rhyolite, andesite, and basalt. The
colour of igneous rocks varies from light
grey, pink and brown to dark steel grey or
black. The dark varieties are generally called
trap, a term derived from trappa, a Swedish
word meaning stair, as the formation frequently
resembles stairs.

Sedimentary rocks are composed of fine rock
particles and fragments which have been pro-
duced by the disintegration of rocks of various
types, carried by running water and deposited
in layers on sea or lake bottoms. Examples of
sedimentary rocks are limestone, sandstone and
shale.

Metamorphic rocks are those which have been
formed by the action of chemical or physical
forces on igneous and sedimentary rocks. Ex-
amples of this class are gneiss, slate, quartzite
and marble.

As far as it is possible to determine the rela-
tive value of the various rocks for road building
according to their mineral classification, it may
be said that the following is the order in which
they should be ranked:

SELECTION OF MATEEIALS 167

1. Trap.

2. Syenite.

3. Non-crystalline Limestone.

4. Chert.

5. Granite.

6. Mica Schist.

7. Quartzite.

Stone from a ledge, because of its uniformity,
is usually better than field stones, but if the
ledge is of an inferior grade of rock it should
not be used merely because it is ledge stone,
in preference to field stones of better quality.
The aim in the selection of a road material
should always be to get a rock of uniform qual-
ity. Badly weathered stone from the surface
or outcrop of a ledge should never be mixed
indiscriminately with the fresh stone from the
interior.

Physical Qualities. — The mineral classifica-
tion of rocks is by no means a conclusive test
of their fitness for road building, as there is a
wide variation in the qualities of different out-
crops and deposits of materials belonging to the
same class and type.

It is the aim of the road builder to obtain a
road with a surface as nearly smooth as pos-

168 BOADS, PATHS AND BEIDGES

sible, not too hard, too slippery, or too noisy,
and which will be as free as possible from mud
and dust. These results are to be obtained and
maintained at as small a cost as possible. In
order to produce even approximately such con-
ditions, it is necessary that only rock possessing
certain essential physical qualities, irrespective
of mineral properties, be used.

In order to determine what qualities are
essential in a road material, it must be borne
in mind that the road will be called upon to
withstand the wearing action of wheels and
horses' hoofs, as well as the action of the ele-
ments, in the form of rain, wind and frost.

Hardness is the quality possessed by rock
which enables it to resist the wearing action of
the wheels and horses ' hoofs. It is evident that
hardness is an essential quality, and particu-
larly so if the road is heavily travelled.

Toughness is that quality in the rock by which
adhesion between the crystalline and fine par-
ticles of the rock is so great as to give it
power to resist fracture when submitted to the
blows of traffic. Its quality is different from
hardness. The difference is illustrated by the

SELECTION OF MATERIALS 169

statement that the resistance by rock to the
grinding of an emery wheel would be consid-
ered hardness, while the resistance to fracture
when the rock is struck by a hammer is tough-
ness.

A third and very important quality in road
material is the cementing or binding power,
which is the property possessed by rock dust
to form a cement or bond when wet, whereby
the coarser fragments of the surface course are
bound together and the whole forms a smooth,
water-proof shell or crust. Since it is abso-
lutely necessary to protect the subgrade from
water, it will readily be seen that the rock which
does not possess sufficient binding power is
likely to form a loose surface, which will permit
the water to sink through and soften the sub-
grade or foundation, thereby destroying the
stability of the whole road.

It is important in the selection of material
for a macadam road to consider the character
of traffic which the road will be called upon to
sustain. To make this point clear, the theory
upon which the macadam road rests may be
again explained as follows : The rock dust which

170 BOADS, PATHS AND BEIDGES

Cross Section, Roman Road (Appian Way).

Cross Section, French Road (Roman Method),
previous to 1775.

Cross Section, Tre"saguet Road, 1775.

Cross Section, Telford Road, 1820.

Cross Section, Macadam Road, 1816.

Cross Section of Modern Macadam (Massachusetts) Road
with V-shaped foundation.

Cross Section of Modern Macadam Road.

SELECTION OF MATERIALS 171

fills the voids between the angular fragments of
stone and forms a cement or binding material
when wet is gradually carried away by wind,
rain and the action of traffic. It is known,
however, that the hoofs of the horses and the
iron-tired wheels of vehicles wear , a sufficient
amount of new dust from the fragments of rock
to replace that which is lost in this manner.
Consequently, the bond of the road is automatic-
ally renewed. If, therefore, a very hard rock
is used in the construction of a macadam road,
heavy traffic will be necessary in order that
there may be sufficient wear to produce the
essential rock dust. If, on the other hand, a
soft material is used for a heavy traffic road,
the rock will be worn away far more rapidly
than is necessary for the automatic binding of
the road. Practical road builders realise that
for very heavily trafficked roads a hard ma-
terial, such as trap rock, is essential, and that
for light trafficked roads limestone or other ma-
terial which is not as hard as trap rock will
serve every purpose.

An important series of experiments con-
ducted by the United States Office of Public

172 BOADS, PATHS AND BEIDGES

Eoads developed the fact that the addition of
limestone screenings to hard material, such as
granite or diabase, increases the cementing
quality to a marked degree. The experiments
were carried still further and lime water was
mixed with the granite. The tests showed in
every case a marked increase in the cementing
value of the granites treated, and the inference
is that the addition of lime will greatly in-
crease the binding power of certain road-build-
ing rocks. As a result of these experiments,
the conclusion was reached that mixtures of
acid and basic rocks give a higher cementing
value than either rock alone.

To enable the road builder to determine the
value of a rock as a road material, a number of
tests have been devised. These tests, however,
require special apparatus, and much skill and
good judgment on the part of the operator.
The Office of Public Eoads of the United States
Department of Agriculture maintains a splen-
didly equipped laboratory where tests and an-
alyses of rocks are made free of charge. No
construction of any importance should ever be
undertaken without having the rock tested, un-

SELECTION OF MATERIALS 173

less it has already been subjected to that best
of all tests, actual use on the road for a number
of years.

Directions are issued by the United States
Office of Public Roads for the selection and
shipment of specimens of road material for
laboratory tests, and if followed carefully, the
selection of the best available material should
be insured. In order to have road materials
tested in the laboratory of the Office of Public
Roads, the instructions below must be carefully
followed :

1. All samples should be selected to represent as
nearly as possible an average of the material.

2. A sample of rock for laboratory tests must con-
sist of stones which will pass through a three-inch
but not through an inch and a half ring — excepting
one piece, which should measure, approximately, four
by six inches on one face and be about three inches
thick. The whole sample should weigh not less than
thirty pounds. It is desired that samples of rock be
shipped in burlap bags.

3. A sample of gravel must weigh not less than
twenty-five pounds, and should not contain stones
over one inch in diameter. Such samples must be
shipped in boxes, sufficiently tight to prevent the
finer material from sifting out.

174 BOADS, PATHS AND BRIDGES

4. A blank form and addressed tag-envelope will
be supplied by the Office for each sample. The blank
form must be filled and placed in the tag-envelope,
which must be used as the address for the sample.
It is essential that the blank form be filled with the
utmost care, as they are filed as records of the samples.

5. The Office desires to keep a record of the actual
wear on roads built of the materials tested. If the
material which this sample represents has been or is
about to be used on roads, this Office would desire
to be informed of the addresses of those in charge of
the construction and maintenance of such roads.

6. Samples must be shipped, freight or expressage
PREPAID, and bills of lading or express receipts
forwarded by mail to the Office of Public Roads, De-
partment of Agriculture, "Washington, D. C.

7. The Office makes no charge for tests.

Distribution of Road Materials. Trap Rock.
— Trap rock is abundant throughout the most
of New England, except in the northern part
of Maine. The best quality is found in the
valley of the Connecticut, south of the Vermont
and New Hampshire line, and .along the coast
between Boston and Eastport, Me. Excellent
trap is found in the upland portion of New
Jersey and in parts of Maryland and Pennsyl-
vania. New York is not so well supplied except
along the Hudson in the vicinity of the Pali-

SELECTION OF MATEEIALS 175

sades. South of the Potomac Eiver trap rock
is limited to the Blue Eidge Mountains and to
the Piedmont country east of the Appalachian
Mountains. In the country between the Appa-
lachian Mountains and the Mississippi Eiver,
very few trap dykes occur. The northern part
of Michigan is abundantly supplied with trap
rock. West of the Mississippi, in southern Mis-
souri, Arkansas and Oklahoma, there are a few
scattered rocks of this nature, but in the Eocky
Mountains, and on the Pacific Coast, excellent
trap rock abounds.

Granitic Rocks. — Granitic rocks, which in-
clude granites, syenites, and the harder gneiss,
follow in general the same distribution as the
trap rocks, and it is said that between the traps
and granites about one-third of the area of the
United States is well supplied with road-build-
ing stone.

Quartzites. — The quartzites are found partic-
ularly in the mountainous districts of the Appa-
lachian and Cordilleran regions, and in the
Ozarks and Adirondacks.

Limestones. — Limestone is found in many
parts of the Mississippi Valley, in the southern

176 EOADS, PATHS AND BEIDGES

parts of Indiana, Ohio, the Valley of Virginia,
in Kentucky, eastern Tennessee, and northern
Alabama.

CHAPTER IX
MAINTENANCE AND REPAIR

THE terms maintenance and repair are very
frequently used as synonyms, but there is a wide
distinction between the two operations. To
maintain a road means to keep it always in good
condition, while to repair a road means to make
it good only occasionally. In other words,
repair sets in after maintenance fails to keep
the road in proper condition. To maintain a
road, therefore, means not to let it become bad ;
to repair it, means to improve it after it has be-
come bad.

There is no phase of the subject of road im-
provement so important, and which is so often
neglected, as that of maintenance. Roads may
be constructed in a most scientific manner, and
out of the best materials available, but unless
they are properly maintained, they will sooner
or later go to pieces. On the other hand, roads
may be very poor, but with systematic main-

177

178 EOADS, PATHS AND BEIDGES

tenance and repair, they may be rendered
passable at all seasons of the year for ordinary
traffic. No road has ever been so well con-
structed that it did not need to be maintained.
Even the tremendously massive roads of the
Eomans have almost disappeared owing to this
lack.

It has been the universal practice in America
to repair the roads at such times as will inter-
fere least with individual duties, and this has
crystallised into repairing the roads once or
twice a year. So hard and fast has this custom
become in many of the States that, even if costly
macadam roads are constructed at great ex-
pense, they are allowed to go to ruin because
minor defects are permitted to go unrepaired
until they result in practical destruction of the
road.

A road is no more than completed before
the destructive forces set in. These destruc-
tive agencies are largely due to traffic and
the elements. They act and react upon
each other in such manner as to make the
determination of the wear due to each a very
difficult matter. It has been estimated that

MAINTENANCE AND BEPAIR 179

ordinarily about 80 per cent, is due to traffic
and 20 per cent, to weathering. Of the former
about 56 per cent, is believed to be due to the
effects of the horses' feet, especially the calks,
and 44 per cent, due to the abrasion of the
wheels. Ordinarily the forces of destruction
may be given in the order of their importance,
as the shoes of the horses, the wheels of the
vehicles, and the weather.

Even the most superficial examination of our
roads tells us that the wear on our highways
is no negligible amount. The hardest rock will
wear, and the most important road problem
before highway engineers to-day is one of road
maintenance, rather than of road construction.
It is worse than folly to build expensive roads
and then expect them to take care of themselves.
Not a few States are awakening to the sad reali-
sation, hastened, to be sure, by the automobile,
that even State-aid roads must be maintained
after they are built.

No more admirable system of maintenance
could be devised than that which is followed in
France. Every mile of road is inspected daily,
and the slightest defect is mended at its incep-

180 KOADS, PATHS AND BEIDGES

tion. The maintenance-of-way departments of
our great railroad systems do not provide a
more thorough inspection of railroad tracks
than do the French for their public roads. The
changes which should come in the American
system will mean the adoption of a continuous
system of repair and a methodical inspection of
all roads.

American Methods of Maintenance. — There
are three systems of road maintenance in use
in this country, viz.: the contract system, the
labour-tax or personal-service system, and the
system which provides men permanently em-
ployed to look after particular sections of road.

The contract system has been used to some
extent in various States, but it has never been
found entirely satisfactory. As a general rule,
the amount paid for this work is small and such
poor service is rendered that in many cases the
roads have become worse rather than better.
Some of the European countries adopted it dur-
ing the last century, but the experiment proved
a failure.

The working out of personal or property taxes
upon the public roads has never proved satis-

EFFECT OF TREATMENT WITH A SPLIT-LOG DRAG.
A road in Iowa before and after dragging.

MAINTENANCE AND EEPAIB 181

factory. No State or community has ever built
or kept in repair a system of first-class im-
proved roads under the personal-service or
labour-tax system. In fact, this system is not
applicable even to earth roads. Its principles
are unsound, its operations unjust, its practice
wasteful, and the results obtained under it are
unsatisfactory in every particular.

Undoubtedly the best system of maintenance
is that which provides for the permanent em-
ployment of skilled labourers or caretakers, who
may have charge of particular sections of road
or who may be assigned to any part of a county
or district where the work is most needed.
Men employed in this way become experts in
their particular line of work, and if they make
mistakes one year, they are pretty apt to correct
them the next ; but, under the labour-tax system,
these mistakes are repeated continuously. If
one man is employed to look after a particular
stretch of road, or to do a particular class of
work, he will soon learn to take pride and in-
terest in his work.

This system has been adopted in this coun-
try only to a limited extent. It has been used

182 ROADS, PATHS AND BEIDGES

by the Massachusetts Highway Commission for
several years. The New York State Highway
Commission introduced it in the year 1910 for
the maintenance of State roads, and Allegheny
County, Pennsylvania, employs it for the main-
tenance of about 100 miles of county roads.

While it would be manifestly impossible to
adopt this system throughout the entire country
on account of limited resources and sparse pop-
ulation, still it is believed that there are many
places where it might be used with great suc-
cess. It would be difficult to find a county
which is so poor that it could not afford to em-
ploy continuously eight or ten labourers and
three or four teams to maintain and repair its
roads ; and many counties could well afford to
employ ten times such a force. That such a
plan would be more effective than either the
labour-tax or the contract system would appear
to be self-evident.

Neglect of Earth Roads. — Of all our roads,
the earth roads are probably the most neg-
lected. Experience has shown that by proper
maintenance a well-constructed earth road can
be transformed into something better than

MAINTENANCE AND REPAIR 183

elongated mud-holes. The first and last com-
mandment in the maintenance of earth roads is
to keep the surface well drained. Water is the
great enemy to our clay and heavy-soil earth
roads, and must be removed immediately, or
much mud is the result. To insure good drain-
age, the ditches must be looked to and obstruc-
tions removed, and the smooth, raised crown of
the road maintained. For this purpose the
split-log drag, or some similar device, is very
useful, and at the same time inexpensive.

The drag should be used while the road is wet
from recent rain and while the clay is plastic
and too wet for the use of a road machine, but
not in such a state as to adhere very much to the
drag. The theory of the drag is simply this:
Most clays and heavy soils will puddle and set
very hard. The drag is essentially a puddling
machine, and hence must be used while the
earth contains enough moisture to puddle. The
drag should be driven up one side of the road
and down the other, inclined at an angle of
about 45 degrees to the line of the road, so that
a little earth is always moved toward the centre.
In this way, the crown will be maintained, ruts

184 ROADS, PATHS AND BRIDGES

and depressions filled, and the entire surface
plastered over with a thin coat of puddled clay
or earth, which packs very hard under passing
traffic. The drying action of the sun and wind
bakes the surface into a hard crust. Continued
use of the drag will soon cause the road to be
literally shirigled over with successive layers of
puddled earth as hard and dense as earth can
be made without costly treatment.

The following points should be borne in mind
in dragging a road :

1. Make a light drag which is hauled over the
road at an angle so that only a small amount of earth
is pushed to the centre of the road.

2. Ride on the drag and never drive faster than a
walk.

3. Begin on one side of the road or wheel track,
returning on the opposite side.

4. Drag the road as soon as possible after every
long wet spell, when the mud is in such a condition
as to puddle well and still not adhere too much to
the drag. A few draggings on any given road will
give the operator a clue to the proper way and best
time to drag.

5. Drag at all seasons of the year, but do not drag
a dry road. If a road is dragged immediately before
a cold spell, the road will freeze in a smooth condi-

MAINTENANCE AND EEPAIE 185

tion and do away with our extremely rough winter
roads.

6. Always drag a little earth toward the centre,
with the aim of keeping the slope of the crown from
% inch to 1 inch to the foot. If the drag cuts too
much, shorten the hitch or change your position on
the drag.

The best results from dragging are obtained
only by repeated applications. One or two an-
nually will not maintain an earth road in its
best condition, unless the traffic is light. Some
gravel roads may be considerably improved by
dragging, especially if the gravel contains any
clay, but it will do no good on a well-bonded
macadam road.

The Sand-Clay Road. — The best method of
maintaining a sand-clay road is by means of a
split-log drag or a reversible road grader. The
small ruts and depressions which are liable to
form under heavy traffic, particularly in wet
weather, should be filled as soon as possible
after they are formed; otherwise the traffic is
liable to cut through the sand-clay surface and
destroy whole sections of the road, making it
necessary to resurface it. The drag or road
machine should be used in damp weather so that

186 BOADS, PATHS 'AND BBIDGES

the surface will pack and bake while the road is
drying out.

If the surface becomes loose in dry weather,
this is an indication that there is not enough
clay in the mixture. This defect may usually
be remedied by a thin application of clay, raked
in with a tooth harrow or worked in by means
of a disc harrow. The mixing should be done
in damp weather, and just before the road dries
out it should be scraped with a reversible
grader or a split-log drag.

If the road becomes sticky or muddy in wet
weather, this indicates that there is not enough
sand in the mixture. A thin layer of sand ap-
plied in wet weather will usually remedy this de-
fect. The sand can ordinarily be worked into
the surface by traffic, although quicker results
can be obtained by " discing " or harrowing.
Small holes and depressions in the surface may
be remedied usually by the application of a
small quantity of sand and clay of the proper
mixture raked Into position with a garden rake.
These patches should be carefully made so that
when they finally consolidate, the surface will
be smooth and free from bumps or depressions.

MAINTENANCE AND KEPAIR 187

Care of Gravel Roads. — A gravel road re-
quires more attention the first year after its
construction than for many years thereafter.
Small ruts and depressions should be filled as
soon after they are formed as possible ; other-
wise, they will catch water, which soaks through
to the foundation, softens the subgrade, and
causes the whole surface to wear rapidly or to
give way entirely. A small quantity of mate-
rial will fill incipient ruts and holes, but if neg-
lected, a cartload of material may be required
to repair a hole, which might otherwise have
been filled by a shovelful.

Small depressions may be filled by adding
fresh gravel, but, as a general rule, all that is
needed is to rake the loose gravel from the side
of the road into them. A split-log drag or
some similar device is very useful for this pur-
pose. If fresh gravel is added, all coarse mate-
rial should be eliminated and the gravel should
contain enough fine material to cement it to-
gether. A little clay is sometimes helpful, but
too much clay will render the road dusty in
summer and muddy in winter.

A gravel road should not be considered fin-

188 EOADS, PATHS AND BRIDGES

islied until it has been in use for at least one
year. If the road has been properly main-
tained, it will be found, after about a year's
service, that the wheels of heavily loaded wag-
ons will not form ruts or depressions in the
surface. The road will require but little at-
tention for several years after it has passed
through this formative period. Attention
should still be given, however, to the side
ditches and to culverts. They should be kept
open and free, so as to permit water to drain
quickly away from the road, especially during
the spring of the year, when the snow and ice
are melting. After a few years it will be found
that the gravel will work toward the sides of the
road, leaving a depression in the centre, which
will prevent or interfere with the flow of the
water from the surface to the side ditches.
This will not be the case, however, if the road is
dragged with a split-log drag, or surfaced from
time to time with a reversible grader.

If the reversible grader is used for this pur-
pose, care should be taken not to shove earth,
sods, or weeds from the side ditches to the cen-
tre of the road, or if this is done, then such trash

GOOD AND BAD MAINTENANCE.

1. (Top.) A French highway and one of its caretaking patrolmen.
2. An American example of worn-out macadam. 3. Rude road-mend-
ing in the southern United States.

MAINTENANCE AND EEPAIE 189

should be, by all means, removed. Hundreds
of miles of fairly good gravel roads are seri-
ously injured every year by this practice of pil-
ing sods and trash in the centre.

THE SPLIT-LOG DEAQ

The best time to use the drag or road machine
on a gravel road is just after a heavy rain,
when the surface is comparatively soft and
when the material which is scraped towards the
centre will pack again into a hard crust. This
work should never be done in dry weather, for
the reason that the loose material will soon turn
to dust or mud.

The crown of the average gravel road should
be maintained at about an inch or three-quar-

190 KOADS, PATHS AND BEIDGES

ters of an inch to the foot. That is, a road
which is 18 feet wide from shoulder to shoulder
should have a crown of not less than 6 inches
nor more than 9 inches. If the crown be
greater than 9 inches, the traffic will be forced
to use the centre of the road, which will soon
cause ruts or depressions to form in the surface.
If the crown is less than 6 inches, the surface
will not properly drain itself. By making the
slope about three-quarters of an inch to the
foot, it will be found that the traffic will use the
whole surface of the road and will, in that way,
distribute the wear much better than with a
higher crown.

If gravel roads are neglected, especially
while they are new, they will soon go to pieces
and the money and labour expended upon them
will be wasted. Constant attention should be
the watchword. If it is estimated that a 5-mile
stretch of road will require a hundred days'
labour each year to keep it in repair, then it is
much better to distribute that labour through-
out the year than to have the work done all at
one time. One man can do better work in main-
taining a gravel road by working 313 days an-

MAINTENANCE AND EEPAIE 191

nually than 313 men can in working one day
annually. The old adage, "A stitch in time
saves nine," applies with equal force to the
maintenance of a gravel road.

Even though a gravel road may be main-
tained in good condition, it will require resur-
facing from time to time, especially if the road
is heavily travelled, or if the material is poor.
For this repair work the very best gravel avail-
able should be used, and the work should, if
possible, be done when the ground is damp, so
that the new material will knit and bond itself
to the old road surface.

It is the usual custom in many communities
in repairing an old gravel road to dump
wagon-load after wagon-load of material in a
windrow in the middle of the road, and then to
leave it in that condition to be spread by the
traffic. This practice cannot be too severely
condemned. These large piles of gravel in the
middle of the road are dangerous, especially at
night to those travelling in buggies or automo-
biles, and many serious accidents are due to
this cause. The material if piled up in this way
is gradually pushed by the traffic towards the

192 EOADS, PATHS AND BRIDGES

side ditches, and by the time the road is con-
solidated, at least 50 per cent, of the gravel is
wasted by being ground and pounded by the
wheels of vehicles, the hoofs of horses and the
tires of automobiles. Even after the road is
consolidated, the surface is full of bumps and
holes, which render it disagreeable to travel
and difficult to maintain.

The best practice in repairing is to dump
each load of gravel in three or four places and
then to pull the material into position with a
garden or other suitable rake, eliminating all
pebbles larger than two inches in diameter.
Another good practice is to spread the material
over the surface with a reversible grader and
then rake it with a tooth harrow. In no case,
should the load from one wagon be dumped in
one place, as this produces a bumpy surface.

The repairing should by all means be under-
taken in the spring of the year, so that the
gravel will have time to consolidate before dry
weather sets in. If the gravel is spread in the
summer or early fall, it will remain loose until
the winter rains come. The water will then
penetrate to the foundation, rendering it so soft

MAINTENANCE AND EEPAIE 193

that much of the gravel will disappear during
the ensuing winter.

Where extensive repairs are to be made, a
steam roller with spiked wheels may be used to
good advantage in tearing up the old roadbed.
A tooth harrow may then be drawn over the
surface, which will permit the dirt, clay and
sand to sift to the bottom and will bring the
loose gravel to the surface. The road may then
be rolled, and a layer of suitable binding gravel
applied, after which it should be sprinkled and
again rolled until it is ready for traffic. The
roller and sprinkler will not be needed if the
materials pack well under traffic, although bet-
ter results can usually be obtained by their use.

Some gravel roads may be considerably im-
proved by surfacing them with a thin layer of
hard, tough rock screenings, such as the traps
and better grades of granite. This method has
been pursued for parks and boulevard roads in
the District of Columbia. A large mileage of
gravel roads has been surfaced with trap-rock
screenings. These roads have the appearance
of macadam and wear practically as well, and
at the same time are much cheaper than if they

194 BOADS, PATHS AND BEIDGES

were built entirely of broken stone. Some of
them have been oiled recently and with very
gratifying results.

Maintaining Macadam Roads. — The causes
of wear on macadam roads are the weather, the
wheels of vehicles and the hoofs of horses. The
weather acts to some extent directly on the
materials, but to a much greater degree indi-
rectly. Frost is one of the most active of these
agencies. The expansion and contraction
caused by frost leads to a general disintegra-
tion of the road surface. "This is especially
true where much clay was allowed in the binder,
where the road surface was porous or the drain-
age poor. When such a road thaws out after
a hard freeze, the macadam will practically be
a layer of loose stones into which the traffic will
cut, forming ruts. Eain, following a frost and
thaw, is especially damaging, and a series of
thaws, rains and frosts, will entirely destroy
the bond in a road when once the water has
gained access into the stone. Frost has but
little, if any, effect on a dry, well-kept road.
The solution is self-evident. Look after the
drainage very carefully in the fall and be sure

MAINTENANCE AND EEPAIE 195

that the surface is as nearly waterproof as pos-
sible, so that the road will, at the beginning of
winter, be dry and not full of water. Violent
rains on exposed localities wash out the binder,
and sometimes the smaller stones as well, leav-
ing the surface both rough and porous. Over-
flows from blocked gutters or choked cross-
drains cause much damage in the same way.
The amount of material lost from the roads by
this means is often larger than the toll exacted
by traffic.

If an excess of water is detrimental to a road,
however, an extended drought is little or no
better. The winds remove the binding mate-
rial both by blowing it directly from the surface
of the road and by carrying off the dust raised
by traffic. This causes the road to " ravel."
These loose stones should be removed, as leav-
ing them on the road not only makes traffic dis-
agreeable, but also tends to loosen still others.
The stones which are picked off the road will
rarely prove of value for repair work, as they
are too much rounded to bond readily.

The wheels of passing vehicles produce on
the road several effects, which should be

196 KOADS, PATHS AND BEIDGES

understood. First, there is the grinding and
crushing action on the surface, and second, the
pressure throughout the entire body of the road
covering. If for any reason the materials are
not thoroughly consolidated, there is a third
action of displacement accompanied by internal
wear as the stones rub against each other. If
the road surface is hard, smooth and water-
proof, the wear will be the least possible and
will be confined to the surface. The aim should,
therefore, be directed toward a constant main-
tenance of a hard, smooth, waterproof surface.
The actual amount of wear on any given road
surface depends on several conditions, viz., the
amount and kind of traffic, climate and other
local conditions, and the kind of road material
used. Generally speaking, however, the amount
of wear is less in proportion as the road is kept
in good condition as to surface, solidity, and
drainage. It is usually less on slight grades
than on dead level, because of the better drain-
age, but on steep hills it is increased by the
effects of running water. Strange to say a hill
usually looks better after a heavy rain than the
flat below. This is because the hill is washed

MAINTENANCE AND EEPAIE 197

clean, while the flat is more or less covered with
the debris and mud carried down from above.
This often leads to a neglect of the hills until
they are so badly worn as to require resurfac-
ing.

The amount of maintenance required will
vary with the season and the local conditions.
Ordinarily there is more wear in winter than
summer, and more in wet places than in dry.
The reverse, however, is true on roads with
heavy automobile traffic, when dry weather
proves especially injurious.

The amount of wear is also greatly aug-
mented by the prevailing tendency of the traffic
to follow in the same track, especially where
the surface is soft, so that the tracks become
visible. In parts of Germany the road labour-
ers have a custom of placing large stones on to
the road whenever a rut or depression tends to
form, because of the concentration of the traffic
along this one line. The stones serve to deflect
the traffic and so keep the wear uniformly dis-
tributed over the entire road surface.

Proper maintenance consists in replacing the
materials lost by unequal wear, so that the road

198 EOADS, PATHS* AND BEIDGES

is always in a good smooth condition. In mak-
ing repairs, the materials should be spread only
on the places which require them. Thus no por-
tion of the surface is neglected, and no mate-
rials are wastefully applied to portions already
thick enough to stand the traffic. Uniformity
in both strength and smoothness with the least
use of materials and least cost is the thing to
be sought. In spreading new stone, the old
method of waiting until the road has entirely
lost its shape and then spreading a thick coat
which is left to be worked in wholly by the
traffic cannot be too severely condemned. This
method is very wasteful of material, as well as
extremely inconvenient to traffic. A great deal
of the material is ground up and crushed be-
fore it is consolidated, and even after consolida-
tion the surface is rarely if ever left smooth.
The materials necessary to replace the loss by
wear of ordinary traffic should be spread in
comparatively small quantities where hollows
or weak places occur, or where required to keep
the cross section of the road in proper form.
If laid in with care and in small patches, the
inconvenience to traffic will scarcely be notice-

MAINTENANCE AND EEPAIE 199

able. If the task of consolidating the materials
laid is to be left to the public, it is only proper
that they should demand that the process be
made as easy and speedy as possible, which is
readily attained by good arrangement and care
in spreading the materials, and close atten-
tion afterwards until they are consolidated.
Where, because of neglect, or other reasons, it
is necessary to make extensive repairs or re-
surfacing, the steam roller should always be
employed to do the consolidation. Especially
is this true if the road is extensively used by
automobiles.

The steam roller is also a very useful machine
in the maintenance of roads softened by winter
frosts. A few trips in the spring of the year
soon after the frost has left the ground will
remove the slight ruts beginning to form, and
recompact the road's surface, rendering it hard,
smooth and waterproof. All loose stones
should be removed before the road is rolled.

The following instructions to road men, is-
sued by The Eoad Improvement Association of
London, should be found useful in the mainte-
nance and repair of macadam roads :

200 BOADS, PATHS AND BEIDGES

1. Never allow a hollow, a rut, or a puddle to re-
main on a road, but fill it up at once with chips from
the stone-heap.

2. Always use chips for patching, and for all re-
pairs during the summer months.

3. Never put fresh stones on the road, if by cross-
picking and a thorough use of the rake the surface
can be made smooth and kept at the proper strength
and section.

4. Kemember that the rake is the most useful tool
in your collection, and that it should be kept close at
hand the whole year round.

5. Do not spread large patches of stone over the
whole width of the road, but coat the middle or horse
track first, and when this has worn in, coat each of
the sides in turn.

6. Always arrange that the bulk of the stones may
be laid down before Christmas.

7. In moderately dry weather and on hard roads,
always pick up the old surface into ridges six inches
apart, and remove all large and projecting stones be-
fore applying a new coating.

8. Never spread stones more than one stone deep,
but add a second layer when the first has worn in,
if one coat be not enough.

9. Use a steel-pronged fork to load the materials
at the stone-heap, so that the siftings may be avail-
able for "binding" and for summer repairs.

10. Go over the whole of the new coating every
day or two with the rake, and never leave the stones
in ridges.

MAINTENANCE AND EEPAIE 201

11. Eemove all large stones, blocks of wood, and
other obstructions (used for diverting the traffic) at
nightfall, or the consequences may be serious.

12. Never put a stone upon the road for repairing
purposes that will not pass freely in every direction
through a 2-inch ring and remember that still smaller
stones should be used for patching and for all slight
repairs.

13. Recollect that hard stone should be broken to a
finer gauge than soft, but that the 2-inch gauge is the
largest that should be employed under any circum-
stances where no steam roller is employed.

14. Use chips, if possible, for binding newly laid
stones together, and remember that road-sweepings,
horse-droppings, sods of grass, and other rubbish,
when used for this purpose, will ruin the best road
ever constructed.

15. Remember that water-worn or rounded stones
should never be used upon steep gradients, or they
will fail to bind together.

16. Never allow dust or mud to lie on the surface
of the road, for either of these will double the cost
of maintenance.

17. Recollect that dust becomes mud at the first
shower, and that mud forms a wet blanket which will
keep a road in a filthy condition for weeks at a time,
instead of allowing it to dry in a few hours.

18. See that all sweepings and scrapings are put
into heaps and carted away immediately.

19. Remember that the middle of the road should

202 EOADS, PATHS AND BRIDGES

always be a little higher than the sides, so that the
rain may run into the side gutters at once.

20. Never allow the water-tables, gutters and
ditches to clog up, but keep them clear the whole year
through.

21. Always be upon your road in wet weather,
and at once fill up with " chips" any hollows or ruts
where the rain may lie.

22. When the main coatings of stone have worn in,
go over the whole road, and gather together all the
loose stones, for loose stones are a source of danger
and annoyance and should never be allowed to lie on
any road.

The Problem of the 'Automobile. — In the last
few years the need of proper maintenance and
possibly even a radical departure from some of
the former methods of maintenance, especially
on roads near large cities and the principal
thoroughfares between cities, has been greatly
emphasised by the advent of the automobile.
We are confronted by a dust problem due to
this new vehicle. Dust has always existed.
The chemical, physical and mechanical agencies
which produce the dust are in no way new.
The automobile, when not equipped with chain
tires, is not a dust producer in that it grinds up
the road material; it takes the dust made by

MAINTENANCE AND EEPAIE 203

other agencies and disseminates it over the sur-
rounding country. The broad-tired, swiftly
moving automobile throws the dust from be-
tween the stones and the strong, deflected wind
current from the car blows the dust from the
road surface into the air to be carried away by
the wind to the detriment of the road, the travel-
lers, nearby residents and bordering foliage.

No one will seriously question the statement
that the automobile has come to stay. Nor
will it be wise, even though it should prove pos-
sible, to limit the speed below that consistent
with the proper safety of all concerned. The
solution must be found, either by a change in the
design of the cars so as to raise less dust, or by
the highway engineer in the construction and
maintenance of the roads in such a manner as
to prevent the formation of the dust, or so as
to retain it on the roadway when formed.
Probably the ultimate solution will come from
both sources. The other part of the solution
rests with the highway engineer. Present in-
dications point to two lines of procedure : pre-
venting the formation of dust, and laying the
dust when formed.

204 BOADS, PATHS AND BEIDGES

The prevention of the formation of dust in-
cludes the selection and use of materials which
give very little dust, that is, those which bond
very well and are very resistant to abrasion,
and second) the use of binding materials other
than rock dust in road construction. One of
the evil effects of the automobile traffic at pres-
ent is that the binder is all blown away, leaving
the surface free to ravel, which in turn produces
more dust to be blown away by the automobile.
By using only the best materials, the dust nui-
sance can be lessened to a considerable extent.
Before a dust preventive of any kind is applied,
however, the road must be in good condition,
i.e., good repair. Dust preventives are simply
another step in road maintenance, and in no way
vitiate the need for a smooth, properly drained
and properly repaired road surface. Having
secured this, you are ready to take the advance
step of applying some dust-layer or surface
dressing to prevent its rapid formation; in
other words, to lessen the wear on the road, for
much dust usually means that the road surface
is wearing rapidly. The dust on the road has

MAINTENANCE AND EEPAIR 205

but two sources, viz., the foreign material
brought on and ground up, such as horse drop-
pings, etc., and the material abraded from the
road surface. It is the latter which chiefly
concerns the highway engineer. The rate at
which it is formed is in a manner a measure of
the wear of the road.

The evil effects however, go much further
than the mere destruction of the road surface.
Travel for health and pleasure is practically
prohibited by the thick clouds which fog up
from the disintegrating surface. This dust is
carried by winds to the neighbouring fields and
houses, to the extreme annoyance of the road-
side dwellers and to the detriment of the crops
and foliage along the way. In not a few places,
the values of otherwise desirable properties
have declined greatly because of the dust which,
in extreme cases, prohibits the use of front
porches and open doors or windows on the side
toward the road. The question of public health
is even a more vital one, however. Dust and
disease are most intimately connected. Tyn-
dall, the great scientist, once declared that the

206 BOADS, PATHS AND BEIDGES

ravages of war are small compared to the vic-
tims claimed by that insidious, relentless arch
enemy of mankind, dust.

The proper use of the various substances
which are used as binders or dust layers is dis-
cussed in the chapter on Modern Eoad Prob-
lems.

CHAPTEE X
EOADSIDE TREATMENT

ROADSIDE treatment has received compara-
tively little attention in the United States, and
yet proper attention to the roadside. is not only
essential to the beauty of the road and to the
pleasure and comfort of the travellers, but also
to the preservation of the road itself.

Roadsides. — After a road is completed, rub-
bish should be removed, and excavations and
embankments, except such as are necessary to
the road, should be smoothed over and sown
with grass, and all unsightly brush and weeds
removed. In short, wherever possible, the
road should run between strips of smooth green
sward, and suitable shade trees should be
planted at intervals, so as to provide a pleasing
appearance, shade for the traveller, and pro-
tection to the road from drying out too rapidly,
provided it is macadam or gravel. Clay and
earth roads should be free of shade. Shade

207

208 ROADS, PATHS AND BRIDGES

trees are an important factor in reducing the
cost of maintenance of macadam roads, by rea-
son of the fact that they prevent the road from
drying out and becoming dusty.

In the selection of shade trees care should
be taken to secure only those which are suitable
to local conditions. In all cases it is well to
choose a tree that is hardy, grows rapidly, and
has abundant foliage. A good plan is to plant
trees with tops fifty feet apart, but alternating
on each side of the road, so that there will be a
tree every twenty-five feet. In some portions
of Germany fruit trees are planted extensively
along the roadside, and a considerable revenue
is derived from the sale of fruit. In Saxony
apple, pear and cherry trees are planted along
the road from 90 to 120 feet apart, and plum
trees about 25 feet apart. Upwards of $21,000
a year has been obtained from the State roads
of Saxony from this source, and still larger
amounts from local roads. In India the Gov-
ernment allows abutting property owners to
take the produce of fruit trees in exchange for
protecting and caring for the trees. The irre-
pressible American boy is a factor which would

5,2 -

11 1

M g g

EOADSIDE TEEATMENT 209

have to be taken into consideration, if such, a
plan were ever contemplated in this country.
With our present inadequate system of mainte-
nance which does not provide for daily patrol,
it would probably be better to resort to forestry
rather than to horticulture for guidance in road-
side tree planting.

Effect of Trees on Roads. — The beneficial
effect which is most generally apparent from
the planting of trees is the prevention of dust
in summer. On the other hand, it is contended
that they prevent muddy roads from drying
out. The presence of trees along the roadside
is generally a partial preventive of damage to
the road from hard, driving rains. A road
shaded by trees is cooler by day and warmer
by night during the summer, and is warmer
both day and night in winter. By preventing
the loss of heat by radiation, trees and tall
hedges reduce the freezing of the road surface
and, consequently, protect the road in a measure
against the destructive action of frost. Shade
also prevents the destructive effect due to rapid
thawing of the road by strong sunshine in the
spring. A great deal of damage is done to un-

210 EOADS, PATHS AND BEIDGES

shaded roads by traffic passing over them while
the rapid thawing process is going on.

Protection From Wind and Snow. — When de-
termining upon the kind of roadside treatment
to be adopted, consideration should be given to
the protection of the road from snowdrifts in
sections of country where the snowfall is heavy.
A study of the relative positions of snowdrifts,
the direction and velocity of winds, and the
relative location of the road, would aid in de-
termining what course to pursue ; for example,
whether trees or hedges would be most advis-
able, and if trees, what kind should be used, or
if hedges, the kind, height, location, and method
of planting.

The protection of stone and gravel roads
from wdnd is very important, as the continued
prevalence of high winds tend to strip the road
surface of the rock dust which is essential to
the bond of the road. The injurious effect
from wind is most pronounced in summer when
the roads are dry. Consequently, if the road-
side is planted with trees or hedges, the foliage
will be thickest in summer, so as to afford a
screen which will materially lessen the force

EOADSIDE TEEATMENT 211

of the wind before it reaches the road surface.

The Kind of Tree to Select. — As previously
stated, the important considerations in the se-
lection of roadside trees are: first, adaptabil-
ity to local conditions ; second, hardiness ; third,
good foliage ; fourth, rapid growth. Wherever
practicable, trees of local origin should be used.

There are a great variety of conditions in
the United States, and it would be impossi-
ble to designate a list of trees which would
be adaptable to all the road conditions which
might exist in this country, unless it were de-
sirable to limit the list to fruit or nut-bearing
trees. If this were the case, the fruit-bearing
trees which would be best adapted to road con-
ditions would be the apple, and possibly the
pear, in some localities. Apples would cover
all that section of the eastern United States
north of the Carolinas, and even south of this
in the Appalachian region. West of the moun-
tains the apple would serve as far south as the
Gulf States, and west to the base of the Eocky
Mountains, with perhaps the exception of the
extreme northern part of Minnesota, the Dako-
tas and Montana, where some other plants

212 BOADS, PATHS AND BBIDGES

would have to be substituted for the apple, un-
less the crab were used. The nut-bearing trees
which are adapted to this use in the eastern
United States are hickory, walnut and butter-
nut for the New England States, and along
the Appalachian Mountains as far south as
Georgia ; but the distribution of these nut trees
would take a northern turn on the west side
of the Alleghany Mountains, and they should
not be used, perhaps, south of central Kentucky,
and no further west than Colorado. The hick-
ory will not thrive in northern Iowa, north-
ern Wisconsin, Minnesota or the Dakotas.
The black walnut, however, will grow well as
far north as the southern part of Minnesota,
over the eastern part of South Dakota, eastern
Nebraska and Kansas. On the Pacific Coast
the English walnut can be used as a substitute
for the nut trees grown in the eastern part of
the United States, and in the South Atlantic
States and the Gulf States pecans may serve
as a substitute for the other nut trees men-
tioned.

Ordinarily it is better to select some long-
lived shade tree than to attempt to combine fruit

EOADSIDE TEEATMENT 213

production with shade. For the New England
and Middle States the sugar maple is one of
the most extensively used and one of the most
desirable shade trees for this purpose. Elm is
very desirable, but it does not produce as dense
a canopy as the maples. If a more dense
shade is desired than that produced by the
sugar maple, the Norway maple may be sub-
stituted. In localities from Washington, D. C.,
southward to the Carolinas, a variety of shade
trees may be employed, such as silver maple,
which is perhaps the least desirable of all ; the
elm and red oak, similar to the varieties growing
on Twelfth Street, Washington, D. C., along
the side of the Smithsonian and Department
of Agriculture grounds ; the willow oak, a fine
example of which is standing just across from
the Henry Monument in the Smithsonian
grounds, Washington, D. C. ; the Norway maple,
which has long been considered as one of the
finest shade trees for that locality; the pin oak,
which is being so extensively used on the streets
of Washington; and the sycamore, which has
a natural distribution throughout the Middle
States. After the confines of the Carolinas

214 EOADS, PATHS AND BEIDGES

have been reached, there is nothing which com-
pares with the live oak. This should be
planted to the exclusion of everything else
throughout the southern part of the United
States, because it is typical of the region and
is one of the most beautiful trees grown in
America. For California probably the pepper
tree will supersede everything else as a road-
side tree, while in Florida, the camphor tree
might well be used as a substitute for the pep-
per tree in California. In extreme southern
Texas the native palm could be used very effect-
ively for roadside decoration. Where this is
not desirable, the hackberry, both native and
Mexican varieties, may be used to good advan-
tage. For the extreme Northwest, including
the Dakotas and northern Minnesota, perhaps
the best roadside tree would be the American
elm or the green ash.

CHAPTEE XI
MODERN ROAD PROBLEMS

ON roads which are subjected to heavy auto-
mobile traffic, the most important problem con-
fronting highway engineers is the prevention
of dust and the preservation of the road from
the destructive action of automobiles moving
at high rates of speed. The standard macadam
road has been found inadequate to withstand
this new form of traffic, especially when the
automobile traffic is dense.

As previously explained in this volume, the
macadam road was designed for the purpose
of withstanding the wear of iron-tired horse-
vehicles. On a macadam road properly con-
structed with suitable material, the amount of
dust worn from the rock fragments is only
sufficient to replace that which is carried away
by wind and rain, so that the bond of the road
is continuously preserved. The advent of the
automobile has brought about new conditions.

215

216 BOADS, PATHS AND BEIDGES

The driving wheels of motor cars moving at
high rates of speed exert a powerful tractive
force on the road surface, which displaces the
materials composing the surface. The result
is that the finer particles and dust are thrown
into the air to be carried off the road by cross
currents of air. The rubber tire of the auto-
mobile does not wear any appreciable amount
of dust from the rock fragments, and conse-
quently, the loss of the rock dust is a permanent
loss to the road. Under these conditions, the
road soon ravels, making travel difficult and
allowing water to make its way to the earth
subgrade or foundation.

In spite of the fact that the automobile is
responsible for these and other unfortunate
conditions, it must be realised that the automo-
bile is one of the most useful inventions of the
age, as it brings distant communities in closer
touch, and places at the disposal of man a
power for the transportation of himself and his
products of infinitely greater possibilities than
animal power. The automobile has come to
stay, and we could no more legislate it out of
existence than we could abolish the railroad and

MODEEN EOAD PEOBLEMS 217

the locomotive. At the present time it is esti-
mated that from 12,000 to 13,000 automobiles
are manufactured every month, and the number
is constantly increasing. Up to the present
time most of the manufacturers have devoted
their energies to supplying the demand for
passenger cars, but the time will undoubtedly
come when the automobile will be used quite
generally for the transportation of farm prod-
ucts to market over good roads. It is neces-
sary, therefore, that attention be directed
toward providing roadways suitable for this
new form of traffic.

Methods of Meeting Conditions. — All rem-
edies which have been tried or suggested in this
connection may be considered in two classes:
first, those which deal with the construction of
new roads, so as to minimise the formation of
dust, and second, those which deal with the treat-
ment of the surfaces of existing roads, to bring
about the same results. In the construction of
new roads various bituminous binders have been
employed with crushed stone, and this type of
road is known as the bituminous macadam. In
the treatment of old roads various bituminous

218 EOADS, PATHS AND BEIDGES

and other binders have been applied to the sur-
face, according to a number of different meth-
ods. The materials which are applied to roads
for the purpose of preventing the formation of
dust may be considered in two classes: first,
those that are applied in their original condi-
tion, and second, those that are applied in emul-
sion or solution in water.

Mineral OiL— This material has been quite
generally used in the treatment of road sur-
faces, with varying success. The oils that have
given the most satisfactory results are those
having an asphalt base. Asphalt forms an ex-
cellent binder, while paraffin has practically no
binding power, and would merely result in mak-
ing the road greasy. The eastern oils contain
almost a pure paraffin base. Some of the Ken-
tucky oils, and most of those in Texas, have a
mixed paraffin and asphalt base, while many of
the California oils contain a high percentage
of asphalt. The oil is applied either in the
crude state or after distillation at refineries,
where the lighter and more volatile parts are
removed. An oil which has been refined in this
way is known as a residual oil, is heavier and

MODERN EOAD PROBLEMS 219

thicker than in its original state, and possesses
a larger percentage of the base. Consequently,
it is, as a rule, better suited for road treatment.
When the oil is not too heavy, it can be applied
to the road surface with an ordinary sprinkling
cart, but when it is too heavy for use in this
way, it is usual to heat it and apply it to the
road by means of a sprayer, either with or with-
out pressure. In the application of surface
binders the best practice is to sweep the road
clean, so that the binder may penetrate and be
incorporated in the body of the road. After
the material has been applied in this way, it is
usual to place a thin covering of gravel, sand
or rock screenings, and rock dust on the road.
In California, oil has been applied to earth
roads which have previously been ploughed up,
and the materials thoroughly tamped and
mixed by means of a tamping or sheep-foot
roller. This method of construction has not
proved successful in the East.

Coal Tar. — Many engineers favour the use of
coal tar for the prevention of dust and the
preservation of roads, but one of the greatest
difficulties is to obtain a universally good mate-

220 EOADS, PATHS AND BEIDGES

rial from different producers. Coal tar is a
thick, black liquid, obtained as a by-product
from the distillation of coal during the manu-
facture of illuminating gas and coke. The base
of coal tar gives its value as a road binder.
This base, which is known as coal-tar pitch,
corresponds to the asphalt base of oils. In the
application of coal tar to roads, the dust should
be removed and the tar applied in practically
the same manner as oil. The refined tar is
usually superior to the crude product, but is
more expensive. The application of tar to
a surface should be made only in dry, warm
weather, and when the road surface is perfectly
dry, as good results cannot be obtained other-
wise. It would hold true, consequently, that
the tar itself should not contain any water,
as the road surface absorbs water more rapidly
than other materials. It is almost always nec-
essary to heat the tar before it can be applied
to the road, and the method is usually to provide
large iron kettles, equipped with portable fire
boxes and mounted on wheels, or, where the tar
is supplied in tank cars, the heating is done
before the tar is removed from the tank. It is

MODEEN EOAD PEOBLEMS 221

applied to the road either by means of a
sprinkling device, or by hand sprinklers and
spread with brooms. The tar should be al-
lowed to dry for a few days before traffic is per-
mitted on the road. The best practice is to
spread a light course of sand or rock screenings
over the surface after it has been treated with
tar.

Solutions and Emulsions. — Materials other
than tars, asphalts and heavy oils, are generally
included under the term "palliatives." Pre-
vious to the introduction of motor vehicles,
water was the agency generally relied upon to
keep the dust down on stone roads. Owing to
the fact that water evaporates rapidly, a num-
ber of chemical salts, having the property of
absorbing and retaining moisture in the atmos-
phere, have been used.

Calcium Chloride. — Probably the best exam-
ple of this form of dust preventive is known as
calcium chloride, a by-product produced in the
manufacture of soda. Calcium chloride has a
great affinity for water, and absorbs and retains
moisture from the atmosphere for a consider-
able length of time. It is, however, only tempo-

222 EOADS, PATHB AND BEIDGES

rary in its effect, as compared with the heavier
binders. It is prepared for application to the
road by mixing with water, and is applied by
means of the ordinary sprinkling cart.

Waste Sulphite Liquor. — A waste product
from the wood-pulp paper-mills has been re-
cently used with some success, but as the base
of this material is soluble in water, it can be
classed only as a temporary binder. The best
results have been obtained from this material by
the application of a concentrated solution of
about 1.13 specific gravity, at the rate of % gal-
lon per square yard. Under favourable con-
ditions, this treatment will keep the dust down
for a whole season, and the material may, there-
fore, be considered as a semi-permanent binder.

Permanent Binders. — Coming now to the
permanent binders, we may consider their use
according to two general methods of construc-
tion, known as the penetration or grouting
method, and the mixing method. Among the
permanent bituminous binders which we have
so far employed are the heavier residual oils
and tars of semi-solid or solid consistency,
fluxed oil and tar pitches and solid native bitu-

MODEEN EOAD PEOBLEMS 223

mens, and fluid cut-back products, which are
capable of increasing in consistency after ap-
plication, by volatilisation of the lighter con-
stituents.

When employing the penetration method, the
best practice is to construct the road as follows :
Upon the subgrade, prepared as for ordinary
macadam work, a foundation course of No. 1
crushed stone is placed to the desired depth
and well rolled. Sufficient screenings are then
applied to fill the surface voids, and care is taken
that there is no excess of fine material which
will prevent the wearing course from keying
into the foundation course. The road is then
rolled until absolutely firm, and more screenings
are applied if necessary to take the place of
those worked into the foundation. The wearing
course of No. 2 crushed stone, clean and free
from dust and screenings, is then applied to a
finished depth of two or three inches and this
course is lightly rolled. The hot bitumen is next
poured or sprayed upon the road at the rate of
from 1 to iy2 gallons per square yard, after
which a light coat of clean %-inch stone chips,
free from dust, is applied and the road is well

224 KOADS, PATHS* AND BEIDGES

rolled. A seal coat of bitumen is then painted
upon the surface at the rate of from a third
to half a gallon per square yard, after which
screenings are applied and rolled in until the
road is smooth and firm.

Such a method of construction should pro-
duce a durable road on which dust formation is
reduced to a minimum. The mixing method is,
however, to be preferred because of the greater
certainty of obtaining an absolutely uniform
wearing surface in which each individual frag-
ment is known to be covered with the binder.

In general the mixing method is conducted
as follows: Upon a foundation course of
crushed stone, prepared as just described, a
mixture of crushed stone and bitumen is laid
to a finished depth of from two to three inches,
and rolled with the addition of screenings. A
paint coat of bitumen is then applied and the
road is finished in the manner previously de-
scribed. The mixture of stone and bitumen
may be prepared either by manual labour or
machinery, preferably by the latter. The min-
eral aggregate may be graded in any approved
manner. For country road work, the crusher

THE AUTOMOBILE AND THE ROAD;

1. Motoring on a road of bituminous macadam. 2. Tearing up the
pike. 3. How fast automobile travel affects a macadamized surface.

MODERN ROAD PROBLEMS 225

run of stone from 2 inches or 1% inches to dust
may sometimes be satisfactorily used. In the
experimental work of the Office of Public Roads
a mixture of 27 parts crusher run of from 1%
inches to % inch with 10 parts crusher run of
from % inch to dust has been found to produce
a very dense aggregate. Such an aggregate
should be mixed with not less than six per cent,
of bitumen, and neither the stone nor bitumen
should be heated above 350° C.

The application of rock asphalt in macadam-
road construction may in a certain sense be
considered as a combination of the penetration
and mixing methods. This material, if contain-
ing a good grade of bitumen, will serve as a
permanent binder. It has been mixed by na-
ture so that each individual fragment is thor-
oughly coated with the binder. It is seldom
suitable for use as a wearing surface of any
considerable thickness, owing to the softness
of the bitumen and to the fineness of the min-
eral particles, which are not, as a rule, well
graded. If forced into the wearing course of
a newly constructed macadam road, to which no
screenings have been applied, it may, as has

226 BOADS, PATHS AND BBIDGES

been demonstrated, prove to be a very service-
able road material which prevents excessive
dust formation by reducing wear and disinte-
gration.

In order that bituminous roads may be kept
dustless it is necessary that they, in common
with all other roads, be treated from time to
time according to one of the first two methods
mentioned earlier in this chapter, that is, they
must either be scavenged, or their surfaces
treated with temporary or semi-permanent
binders. It will be found that the use of a good
semi-permanent bituminous binder in compara-
tively small amounts will not only lay the dust
satisfactorily upon these roads, but that such
treatment will appreciably lengthen the life of
the road by revivifying the old binder originally
used during construction.

Portland cement is in some respects an almost
ideal permanent road binder, especially when
motor traffic only is encountered. When mixed
in proper proportions with a suitable mineral
aggregate it produces a hard rigid concrete,
well designed to withstand the shearing strains
exerted upon it by the driving wheels of auto-

MODERN EOAD PEOBLEMS 227

mobiles, and practically unacted upon by the
large pneumatic tires of such vehicles. Under
steel-shod horse-drawn traffic it is, however,
far from ideal, owing to its lack of resiliency
and tendency to spall under impact and abra-
sion.

Investigations are now being conducted by the
Office of Public Roads with a view to finding some
way of overcoming these undesirable properties.
While much experimental work will yet have to be
done along this line, what has already been accom-
plished would seem to indicate that certain fluid
petroleum residuums may be used to advantage in
wet cement concrete mixtures, both for the purpose
of waterproofing the concrete and reducing its ten-
dency to spall. It has been found that there is little
difficulty in incorporating petroleum residues with
such mixtures, providing they are sufficiently fluid to
be handled when cold, and some of the oils seem to
produce no loss in the strength of the concrete in
which they are used. We hope in the near future to
try out some of these mixtures in the construction of
experimental roads where it will be possible to study
the results produced under actual service conditions.
Until this is done it is, of course, impossible to draw
any definite conclusions in regard to the practical
value of mineral oils as road preservatives and dust
preventives in the construction of cement concrete
pavements.

228 EOADS, PATHS AND BRIDGES

In conclusion a word may be said in regard
to the value of an oil binder in earth-road con-
struction. While the experiments conducted by
the Office along this line have been in no sense
failures, it would seem that in the eastern part
of the United States at least, the oiled earth
road is not destined to prove a success. This
is due both to the character of the oils which
have to be used and to the rather severe climatic
conditions encountered here.

CHAPTER XII
PATHS

THEKE are many sections of the country where
the roads are so poor as to render them prac-
tically impassable for pedestrians, especially
during the winter months. In other parts of the
country where the roads are improved, the auto-
mobile and wagon traffic is very frequently so
heavy as to render the roads not only disagree-
able but dangerous to travel on foot. School
attendance in many rural districts is sometimes
interfered with, and in some instances the
schools have to be closed on account of bad roads
for varying periods during the winter months.

With the expenditure of a comparatively
small amount of money, sidewalks or side paths
could be built to accommodate pedestrians along
the main roads where the conditions above de-
scribed prevail. Side paths would facilitate
school attendance and at the same time encour-
age the healthful exercise of walking, a pastime

229

230 EOADS, PATHS AND BEIDGES

that is too seldom indulged in by the average
American.

Paths should be located on the highest side of
the road on the slope or shoulder just outside
of the surface ditch. A strip of sod a few feet
in width should be provided between the path
and the road, as otherwise it will be found, if
the path is on the same level as the road, that
teamsters will drive their heavy wagons and
horses over the line of the path and destroy it.
The width of such paths need not be greater
than 2 or 3 feet.

A Sand-Clay Path. — For all ordinary pur-
poses, a path built out of a mixture of sand and
clay, or out of fine gravel, will serve every pur-
pose. No foundation will usually be required,
as the paths are not subject to heavy loads. If
the ground over which the path is located is
composed of clay or loam, and the surfacing is
to be made with sand and clay, or sand and
loam, the ground should be ploughed up slightly
and then covered with a thin layer of sand.
This sand should be mixed with loam or clay by
means of a garden rake. The mixing should be
done when the soil is comparatively damp, and

231

the mixture should contain from 85 to 90
per cent, of sand and from 10 to 15 per cent,
of clay or loam. After the mixing process has
been completed, a thin layer of sand should be
applied to keep the clay or loam from becoming
muddy or sticky in wet weather. The path
should be slightly crowned so as to shed surface
water, and small tile culverts should be placed
under it at low places, so as to prevent washing.
It will be unnecessary, as a general rule, to con-
struct bridges and culverts for the paths, as the
ordinary bridges and culverts of the roadway
can be used by pedestrians.

It will sometimes be found that the surface
soil by the roadside contains about the right
mixture of sand, gravel and clay to make a good
path, and under such circumstances, all that is
needed is to clear the right of way and remove
weeds, rocks and other obstructions, and crown
the surface. Where gravel is used, all large
pebbles should be raked out and discarded or
used for the foundation. There is nothing
quite so disagreeable as to walk on a road where
the surface is covered with large stones or peb-
bles,

232 ROADS, PATHS AND BRIDGES

Stone Screenings, Cinders, etc. — Cinders are
very frequently used for side paths, but as they
are lighter and more friable than gravel, sand
or crushed-stone screenings, they are more liable
to wash, and consequently do not give as satis-
factory results. Crushed sandstone, limestone
chips and screenings, or other screenings, make
good materials for paths, provided no piece is
larger than % or % inch in diameter, and that
the mixture contains enough fine material to
cover the coarser screenings. As a general
rule, 2 or 3 inches of any of the materials above
mentioned will be sufficient. The materials
may be laid directly on the sod or soil, as this
insures better drainage than would be secured
by digging a trench into which these materials
are placed.

When side paths are built in thickly settled
regions, or in the neighbourhood of towns and
villages, it is often found desirable to construct
them out of more permanent materials than
those referred to above. The materials ordi-
narily used for this purpose are brick and con-
crete.

This advice applies in a general way to the

PATHS 233

construction of paths about one's house and
grounds.

Brick Walks. — In building brick paths, an
excavation of 4 or 5 inches should be made to
the desired width of 3 or 4 feet. The founda-
tion may be composed of cinders, gravel or
crushed stone, placed to a depth of from 2 to 3
inches, and covered with a layer of sand to a
depth of about 1 inch. A curb should then be
laid on both sides of the walk, composed of
bricks set on end with the upper ends flush with
the surface of the ground. The bricks for the
walk should be laid flat and not on edge. Every
alternate brick should be laid lengthwise of the
pavement, so as to avoid long cleavage lines or
cracks. The bricks should then be tamped into
position under a board, or, if possible, rolled
with a light roller. The surface is then cov-
ered with a thin layer of fine sand which is
broomed into the cracks.

Walks of Portland Cement. — The success of
a cement sidewalk is largely dependent upon the
provision of the following essential features of
construction :

234 BOADS, PATHS AND BEIDGES

1. A firm, but porous foundation, to provide means
for draining off rain water.

2. A sufficiently thick base of well-made, strong
concrete.

3. A wearing coat of rich mortar, troweled to a
smooth, dense surface.

4. The division of the walk into blocks, with lines
of weakness between them, so that all cracks due
to settlement, shrinkage or frost, will be made to
occur at the joints, and will thus not be notice-
able.

If proper drainage is not provided under a
cement sidewalk, rainwater will accumulate,
and in consequence the frost action will be
severe in causing heaving in cold weather, and
unequal settlement of the walk will occur when
the ground is wet. Good drainage may be
secured by laying a foundation of cinders,
broken stone, gravel or coarse sand. Before
laying the foundation, the ground is excavated
to the proper depth and is well consolidated by
ramming. The depth of the foundation course
is dependent on the climate and the nature of
the soil. In cold climates, or where the ground
is soft, the foundation should be from 4 to 8
inches deep, while, in the more temperate cli-
mates, where no frost occurs and the soil

PATHS 235

is sandy and not likely to become soft or water-
soaked, no foundation is required.

The foundation course should be thoroughly
rammed to present a firm, unyielding surface,
and if sand or cinders are used, they should be
thoroughly wet when being compacted.

The main body of the concrete walk is made
of coarse concrete and is called the base. The
usual proportions for the cement base are one
part of cement, two or three parts of sand, and
five parts of broken stone or gravel.

Nothing but good Portland cement should be
used in sidewalk construction. Natural cements
are unsuitable, since they will not stand the
wear, while Puzzolan cements are likely to suf-
fer deterioration through the action of wear
and weather.

The sand used in the concrete mixture should
be clean and coarse; the stone should be hard
and tough, and as free from dust as possible
If gravel is used, it should be thoroughly
screened and should be free from clay or other
matter likely to interfere with the proper adhe-
sion of the mortar. Gravel as it comes from
the banks should not be mixed with the cement

236 ROADS, PATHS AND BRIDGES

to form concrete, but the sand should be
screened out and recombined with the coarse
particles in the desired proportion. The
cement, sand and stone, or gravel, should be
mixed with enough water to form a mixture of
quaking or jelly-like consistency. Care should
be taken to mix the materials thoroughly, so
that each piece of stone will be coated with
mortar.

Forms should be provided along the sides of
the walk to confine the concrete. These may be
made of wooden strips 1% inches thick and of
suitable depth, depending on the thickness of
the concrete base. The strips should be nailed
to wooden stakes, so that the tops are level with
the finished surface of the walk.

It is necessary to lay the concrete base in
blocks with definite lines of separation, so that
in the event of settlement, shrinkage or tem-
perature changes, the irregular cracks which
would otherwise form will be made to occur in
straight, well-defined lines. The separation into
blocks may be made by steel plates or strips
about ^4 inch thick, which are removed just be-
fore the final finish and joint is made. Another

PATHS 237

method is to lay the blocks alternately and fill in
between them. Good results can be obtained by
cutting the concrete course to a width of %
inch, and finishing the top coat into the cut to
the depth of 1 or 2 inches, and cutting with a
trowel through both to separate the blocks when
finished.

The size of the blocks depends upon the width
of the walk. Blocks nearly square in shape
have a better appearance than elongated blocks.
The limit of size for a 4-inch walk is generally
placed at 6 feet square.

The mortar wearing-surface should be placed
as soon as a few of the concrete blocks have been
placed, and before they have set. This surface
consists of a mixture of cement and sand, cement
and finely crushed stone, or cement and a mix-
ture of sand and finely crushed stone. Care
should be taken to proportion the materials
exactly, and thoroughly mix them so that the
surface will be of uniform colour throughout.
The size of crushed stone usually specified is
that which will pass a %-inch sieve.

The consistency of the mortar to be used is
such as is ordinarily employed by a mason in

238 EOADS, PATHS AND BEIDGES

laying brick. The mortar after being depos-
ited on top of the concrete base is smoothed to
the level of the side form by means of a straight
edge guided by the top of the forms. The sur-
face is then roughly floated with a plasterer's
trowel, and soon after levelled with the straight
edge. The final floating is not performed until
the mortar has been in place from two to five
hours, when it has partially set. For this ope-
ration a wooden float is first used and then a
metal float, or plasterer's trowel. It is some-
times the custom to sprinkle a thin layer of
" dryer," a dry mixture of 1:1 mortar, which
is trowelled over the surface. This is not desir-
able, since it tends to make the walk glassy after
floating.

The surface should be grooved. The mason
locates the joints between the blocks of concrete
by marks previously placed on the wooden side
forms. The exact location of the joints is
found by running a small trowel down into the
joints in the concrete. By the use of a steel
straight-edge the mortar coat is cut through in
order to form the individual blocks. The cor-
ners of the cuts are rounded off by the use of

PATHS 239

a groover and edging trowel, which is a small
float with one of its edges curved. A metal float
is used over the entire surface to give it a final
finish. To obtain a rough surface, a dotted or
grooved roller may be employed.

It is advisable to protect the walk from the
hot sun for several days after its completion;
otherwise the surface is likely to dry out too
quickly, with the consequent formation of
shrinkage cracks.

The following table is compiled from the spec-
ifications for cement sidewalk construction, as
practised in some of the larger cities throughout
the country.

240 EOADS, PATHS AND BEIDGES

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CHAPTEE XIII
CULVERTS AND BRIDGES

BEIDGE construction is a very technical and
highly specialized field of engineering in which
the layman is not likely to make great head-
way. Nevertheless, there are many considera-
tions regarding the construction and mainte-
nance of culverts and small bridges which the
layman can comprehend as well as the expert,
and to these we desire especially to call the read-
er's attention.

By far the greater number of culverts and
bridges on our public roads have a span of less
than 50 feet. In the past these structures have,
in general, been built of wood, but lumber so
exposed is subject to rapid decay. Conse-
quently, these structures require a great deal of
repair and frequent renewals. The ever-in-
creasing price of lumber is making the further
use of wood for this class of structures more
and more indefensible. The loads which our

241

242 BOADS, PATHS' AND BEIDGES

highway structures are called upon to sustain
are also increasing. In many localities the
movement of steam road-rollers and heavy trac-
tion engines is seriously hampered because of
weak bridges and culverts. Thus, considera-
tions of both economy and safety demand the
use of other materials than wood in the con-
struction of our culverts and bridges.

Road Bridges. — Eoad authorities should, in
general, adopt some systematic plan of replac-
ing all wooden structures as fast as they require
renewal with permanent materials, such as con-
crete, and they should take particular pains to
make sure that all new structures have sufficient
strength to carry a heavy road-roller.

Wood should never be employed, except for very
good reasons. When it is found necessary to use
wood for the smaller culverts and bridges, certain
practical, rather than theoretical, considerations
should govern the builder. All beams and stringers
should be carefully inspected and only those free
from bad knots and other defects should be used.
For flooring, select a lumber that is hard and tough.
Planks that show a tendency to splinter should not be
used. For 2- and 3-inch flooring, the spacing of the
stringers should not exceed 2 feet in the clear. If
the stringers are spaced as wide apart as the strength

CULVEETS AND BRIDGES 243

of the new plank permits, then in a short time when
the plank is worn by traffic, failure will occur.
Hence, to get the greatest possible amount of wear out
of your flooring space the stringers closely.

Culverts. — Three prime requirements are
necessary in the design of road culverts, viz.,
ample waterway, strength and durability. All
culverts and bridges should be designed and
built strong enough to carry safely the heaviest
load which is ever likely to be hauled over the
road. For short spans, this is usually a heavy
steam road-roller. Many of the existing
culverts and bridges are far too light to carry
the loads which they should legitimately be
required to carry. This is especially true where
traction engines are numerous.

Durability is of the greatest economic im-
portance. In many sections a large portion of
the annual road levy is expended in repair and
renewal of wooden culverts and minor bridges,
and it is not unusual to find this practice de-
fended on the grounds that the county or dis-
trict cannot afford to build the higher-priced
permanent culverts. This is simply a false
sense of economy. True, the first cost of the

244 EOADS, PATHS AND BEIDGES

permanent structure is greater, but there the
outlay ends, while with wooden culverts, there
is a large annual outlay for repair, as well as
frequent renewals. 'Anyone interested in road
improvements will find it most interesting to
secure the following data for his own county
or district: The number of culverts, cost of
labour and material for repair and renewal each
year, average life of wooden culvert, and the
average life of wooden bridge floors. Then he
could compute how long it would be before the
actual present expenditure would pay for per-
manent culverts.

One of the frequent causes of the failure of
culverts and bridges is due to inadequate water-
way. Great care should be taken to provide a
waterway ample to carry safely the largest
storm-flow ever likely to occur. If the water-
way is too small there is constant danger of a
washout with interruption to traffic and high
cost for repairs. On the other hand, if the
waterway is made unnecessarily large, the cost
of construction may be needlessly increased.
Economical designs are those which provide

CONCRETE CULVERTS AND BRIDGES.

1. (Top.) Bridge of concrete on the State highway at Bucklin,
JVfass, 2. Tile culvert. 3. Arched culvert. 4. Culvert of the box type.

CULVERTS AND BEIDGES 245

adequately, but not extravagantly for all neces-
sary requirements.

It is inadvisable to carry storm water any
considerable distance along the road. Water,
especially where the volume is ever likely to be
large and the velocity high, is a grave source
of danger. Every effort should be made to turn
water away from the road before it gathers
in sufficient volume to be dangerous. To lead
water long distances along the road, so as
to require but few culverts, is the poorest kind
of economy, as well as faulty engineering. It
is courting trouble and inviting disaster.

Pipe Culverts. — In many sections pipe culverts

are proving very serviceable for sizes ranging
from 12 to 24 inches in diameter. Because of
the ease with which the smaller sizes of pipe

246 EOADS, PATHS AND BEIDGES

clog and so become unserviceable, it is in general
inadvisable to use for culverts sizes less than
12 inches in diameter, even though the amount
of water to be removed could be carried by a
smaller pipe. The kinds of pipe most com-
monly used are terra-cotta, concrete and
iron.

Terra-cotta, or tile culverts, should be laid
very carefully with the earth well tamped
around them and provided with masonry or con-
crete end walls. There are three common
causes for the failure of tile culverts : washouts,
breakage by passing traffic, and breakage due
to the expansive action of ice. These can, in
general, be easily prevented. Washouts can be
prevented by using a tile of proper size with
careful placing, and the construction of suitable
end walls — a point of great importance. End
walls should 'be carried well below the pipe to a
good foundation, and provision should be made
against possible undermining by erosion.

If the soil is fine sand, or very friable, the
joints should be laid in cement. When the soil
is tough clay, hard pan or similar formation,
this is not necessary, but in every case the earth

CULVERTS AND BEIDGES 247

should be carefully tamped beneath and around
the tile.

To prevent breakage by passing traffic, it is
in general only necessary to place the tile at a
greater depth below the surface than has been
customary. The most frequent causes of break-
age is on earth roads, where the wheels of heavily
loaded wagons cut deep ruts, sometimes actually
striking the pipe, when, of course, failure takes
place. The remedy is obvious. On earth roads,
place the tile at such depth that wheels will not
cut to or near it. To prevent the softening of
the earth, provide good surface drainage. A
load or two of gravel spread over the road at
this point will also be of much assistance. In
general, never place a tile culvert nearer than
18 inches to the surface on an earth road.

In cold climates, and especially in the prairie
regions, tile culverts are often broken by the
expansive action of the ice in winter. A tile
culvert should never be placed where there is
danger of the drainage being obstructed in
such manner as to allow water or slush to
accumulate in the pipe and then freeze. When
the pipe is as much as two-thirds full of water

248 EOADS, PATHS AND BEIDGES

or slush, hard freezing will invariably burst it.
For this reason, tile culverts must be used with
caution in all cold countries, and especially in
the flat prairie regions, where the natural drain-
age is poor.

Iron-Pipe Culverts. — With regard to iron-
pipe culverts, the same care should be taken

CONCRETE. CUL.VERT
STEEL. 1-etflM-o

in laying and placing the end walls as with
tile culverts. Improvements in the manu-
facture of iron have made this material more
generally available for use in culvert construe-

CULVERTS AND BRIDGES 249

tion. A special quality of iron, very low in
carbon, is found to resist corrosion so well as to
make its use advisable in many cases. The old
style of cast-iron pipes is too heavy ever to come
into general use. Corrugated iron pipe, how-
ever, when made from material of the proper
quality, possesses strength together with dura-
bility and lightness. Corrugated iron pipe can
be laid with somewhat less covering than tile
pipe, and will successfully resist the expansive
action of ice. It can, therefore, be used in
places where it would be folly to place tile.

Concrete-Pipe Culverts. — Concrete, both plain
and reinforced, is used to some extent in the
manufacture of culvert pipes. When care-
fully made of proper materials, they are very
serviceable. In general, it may be said that for
the use of plain concrete culvert pipe, the same
considerations govern as for the tile pipes, while
the reinforced concrete culverts may be used
wherever under other considerations the cor-
rugated iron pipe could be used.

End Walls. — What the foundation is to a
house the end walls are to a culvert. Without
suitable end walls, a culvert is without protec-

250 EOADS, PATHS AND BEIDGES

tion and is placed in danger at every severe
storm. Where the fill is high, wing walls may
be used to hold it back, but for most pipe culverts
they are not needed. In friable soils, and when-
ever the velocity of the water is high, the space
at the outlet end of the pipe should be paved to
prevent erosion and danger of undermining the
end walls. The end walls should be carried
down to soil sufficiently firm to prevent any set-
tlement.

The materials for end walls may be brick,
stone or concrete. If bricks are used, they
should be hard burned and laid in cement mor-
tar. Concrete is in general the best material for
use in the construction of wing and end walls.
The concrete should be about a 1:2% :5 mixture
The length of end wall should be about D + 3 H,
where D equals diameter of pipe and H equals
height of fill above bottom of pipe.

Concrete Culverts. — In general the best ma-
terial for use in the construction of culverts and
the smaller bridges is reinforced concrete. The
first cost of a reinforced concrete structure is
naturally higher than that for a wooden one,
but if properly built in the first place, the struc-

CULVEETS AND BEIDGES 251

ture will be permanent and the items of repair
and renewals will be eliminated. Safety, which
is of the greatest importance, will also be
secured from the outset.

There are four general types of concrete
culverts and bridges, i. e., box, T-beam, I-beam

fttafenat Reavirecf
JGBbls. Port/and Cement

IOCurcts.S1on«

exf/afteavy. or
4f-

and arch. The box culvert may be used up
to spans not to exceed 10 or 15 feet. The floor
is a plain slab of reinforced concrete, while the
abutments, wing walls and bottom may be built

252 EOADS, PATHS AND BEIDGES

of either plain or reinforced concrete. Where
it is not necessary to protect the foundation
from erosion, or increase the heaving of the
soil, the concrete bottom may be omitted or,
in some places, a cobblestone paving may be
economically substituted.

For spans above 10 or 15 feet, the T-beam
type is quite generally used. Instead of in-
creasing the thickness of the slab, the additional
strength is secured by building longitudinal
beams beneath the floor slab to carry the load.
The beams and floor slab are built simultane-
ously, and steel reinforcement is placed near the
bottom of the beam and also near the bottom of
the floor slab. In the I-beam culvert steel I-
beams are placed beneath the floor slab to carry
the weight. The concrete covering of the beams
is added simply to protect the steel from corro-
sion. This type of culvert is very readily con-
structed with but little skilled labour, and has
in many sections proved very economical.

The arch culverts may be built of either plain
or reinforced concrete, and are adapted for
almost any length of span, provided the foun-
dation is good and ample headroom may be had.

CULVEETS AND BEIDGES 253

Arch culverts and bridges must be very care-
fully designed and require close supervision
during construction. Where the headroom is
small, or the foundation poor, the arch type will,
in general, not be found economical. Under
no consideration, however, should this type of
structure be attempted unless competent engi-
neering assistance is available, both for the de-
sign and supervision of the construction.

Forms. — Much ingenuity and skill is required
to secure economical forms which also provide
for the necessary strength and tightness. The
appearance of the concrete depends much upon
how well the forms are made. Every crack
between the boards and every joint that is
poorly made or any other imperfection in the
forms is filled with the wet concrete and leaves
its impression upon the finished structure. For
the boards next to the concrete, it is well to use
green, or only partially seasoned, lumber, which
is not so likely to warp and swell out of shape.
For the parapets and other surfaces which will
be exposed to view, it is advisable to use planed
lumber. "Working a spade or shovel along the
boards will crowd back the larger particles,

254 EOADS, PATHS' AND BRIDGES

allowing the finer mortar to flow close to the
boards, thus forming a smoother surface. The
forms should be coated with soft soap or crude
petroleum in order to prevent the concrete from
adhering to them. On the parapets, wing walls,
etc., the forms may be removed as soon as the
concrete will safely hold its shape, and these
exposed surfaces may be rubbed smooth with a
wooden or brick block.

The main part of the forms should not be
removed until the concrete has attained suffi-
cient strength to carry safely the stresses to
which it will be subjected. The time required
will vary with the brand of cement used and the
temperature. Concrete sets much more rap-
idly in warm than in cold weather. Ordinarily,
the forms may be removed in from one to three
weeks after the placing of the concrete.

Mixing and Placing Concrete. — In large quan-
tities concrete is most economically mixed by
machine. In smaller quantities, however, it is
better to do the mixing by hand labour.

The following considerations should always
be kept in mind. The materials should be so
proportioned as to secure the densest mixture

CULVEETS AND BRIDGES 255

possible. The materials should then be so thor
oughly mixed that each particle will be coated
with a thin coat of mortar. In general work,
for those parts requiring great strength, the
proportion of 1:2:4, that is, by measure, one
part cement, two parts sand, and four parts
broken stone or gravel, gives satisfactory re-
sults. For hand-mixing a platform 10 or 12
feet square will be found advantageous. The
sand is first placed on the platform and the
cement added. The sand and cement are then
turned with shovels until the mixture has a uni-
form colour. The stone or gravel is then placed
on top, water is added with a bucket or hose,
and the turning is continued until the whole is
thoroughly and uniformly mixed.

Metal wheelbarrows are commonly used to
convey material from the mixing platform to
the forms. As the concrete is placed in the
forms, it should be well tamped. The consist-
ency of the concrete should be about such that,
after thorough tamping, water should flush to
the surface, and the concrete should have the
appearance of quaking like a mass of jelly.

It is neither possible nor advisable in one

256 EOADS, PATHS AND BEIDGES

chapter to go into the details of bridge design.
These belong to the highly specialized and tech-
nical field of bridge engineering. "We have en-
deavoured only to cover those subjects for the
proper understanding of which a high degree
of specialized knowledge is not necessary.
When it comes to structures of any considerable
size, we can not be too emphatic in urging that
competent engineering supervision be secured,
both for the design and construction. Every
question of both safety and economy in bridge
construction has competent engineering super-
vision as a prerequisite. We know of no other
way in which both safety and economy can be
assured.

AUTHOEITIES CONSULTED

In the preparation of this book the following au-
thors were freely consulted.

AITKEN, THOMAS — Road Making and Maintenance,
London, 1907.

BAKER, IRA 0. — A Treatise on Roads and Pavements,
New York, 1905.

BERGIER, NICHOLAS. — History of Great Highways of
the Roman Empire, Brussels, 1728.

BLOODGOOD, S. DsWiTT — A Treatise on Roads, Al-
bany, N. Y., 1838.

BRUCE, P. A. — Economic History of Virginia in the
Seventeenth Century, Vol. I.

BYRNE, AUSTIN T. — Highway Construction, New
York, 1907.

COANE, JOHN MONTGOMERY — Australasian Roads, Mel-
bourne, 1908.

ELLIOTT, CHARLES G. — Engineering for Land Drain-
age, New York, 1910.

FROST, HARWOOD — The Art of Road Making, New
York, 1910.

GALLATIN, ALBERT. — Roads and Canals, Report to U.
S. Senate, April 6, 1808.

GILLESPIE, W. M. — A Manual of Road Making, New
York & Chicago, 1871.

GILLETTE HALBERT P. — The Economics of Road Con-
struction, New York, 1906.
257

258 BOADS, PATHS AND BEIDGES

GEEENWELL, ALLAN AND ELSDEN, J. V. — Roads, Lon-
don, 1901.

HERSCHEL, CLEMENS — The Science of Road Making,
New York, 1894.

HOOLEY, E. PURNELL — Management of Highways,
London.

HUBBARD, PREVOST — Dust Preventives and Road
Binders, New York, 1910.

HULBURT, ARCHER BUTLER — Historic Highways of
America, 16 Vols., Cleveland, 0., 1902.

JEFFREYS, REES — Dust Problem Statistics, London,
1909.

JENKS, JEREMIAH W. — Road Legislation for the Amer-
ican State, Baltimore, Md., 1889.

JOHNSON, J. B. — Engineering Contracts and Specifi-
cations, New York, 1902.

JUDSON, WILLIAM PIERSON — Road Preservation and
Dust Prevention, New York, 1908.

LATHAM, FRANK — The Construction of Roads, Lon-
don, 1903.

LOVEQROVE, E. J. — Attrition Tests of Road-Making
Stones, London, 1906.

Low, HENRY AND CLARK, D. K. — The Construction of
Roads and Streets, London, 1901.

Preliminary Report of Inland "Waterways Commis-
sion, U. S. Senate Document 325 60th Congress,
1st. Session.

RICHARDSON, CLIFFORD — The Modern Asphalt Pave-
ment, New York, 1908.

RINGWALT, J. L. — Development of Transportation

AUTHORITIES CONSULTED 259

Systems in the United States, Philadelphia, Pa.,

1888.
RYVES, REGINALD — The King's Highway, London,

1908,
SEARIGHT, THOMAS B. — The Old Pike, Uniontown,

Pa., 1894.

SHALER, N. S. — American Highways, New York, 1896.
SPALDING, FREDERICK PUTNAM — A Text Book on

Roads and Pavements, New York, 1908.
TILLSON, G. W. — Street Pavements and Paving Mate-
rials, New York, 1908.
TUCKER, JAMES IRWIN — Contracts in Engineering,

New York, 1910.

Annales Fonts et Chaussees, Paris.
Engineering and Contracting, Chicago.
Engineering News, New York.
Engineering Record, New York.
Good Eoads, New York.
Surveyor, London.
Zeitschrift fur Transportwesen
und Strassenbau, Berlin.

Bulletins of U. S. Office of Public Roads.
Bulletins of U. S. Department of Agriculture.
Bulletins of U. S. Geological Survey.

THE END

INDEX

Appian Way, 10.

Asphalt, ancient use of, 5, 17.

See BITUMEN.
Automobiles, effect on roads,

202, 215.
Authorities consulted, list of,

256.

Binders, permanent, 222.

Binding qualities of various
stones, 169.

Bitumen, application of as a
binder, 224.

Bond-issues for road-improve-
ment advisable, 52.

Bridges, general considera-
tions, 241.

Britain, Roman roads in, 12.

Broken-stone roads. See MA-
CADAM.

Buckshot, or gumbo soil, 114.

Calcium chloride as a binder,

221.

Carthage, roads of, 8.
Causeway, Egyptian, built by

Cheops, 4.

Cement walks, how made, 233.
Chariots of the ancients, 4.
Chert gravel, qualities of, 129.
Clays, properties of, 113, 116.
Clay road. See SAND AND

CLAY EOAD.

Concrete walks, how built,
233,

Convict labour on highways,

46.

Crushers for stone, 147.
Culverts, construction and

types of, 243-256; proper

placing of, 94.
Cuts and fills, directions for,

98-101, 151.

Disc harrow and its use, 103.

Ditches, form and arrange-
ment of 90, 105.

Drag, the split-log, form and
use of, 183, 189.

Drainage of roads, importance
of, 87 ; methods of insuring,
88-98, 152^155.

Dust, controlling the evil of,
204, 217, 226.

Dynamite, use of in road-mak-
ing, 142.

Earth road, the, care of, 182;

construction of, 79-109.
Economics of good vs. poor

roads, 54-61.
England, early road-making

in, 24; Turnpike Acts, 27.
Epaminondas of Thebes, 8.

Flaminian Way, 10.
France, origin of road system
in, 20, 22.

261

262

INCEX

Grade of a road defined, 82;

method of determining, 85.
Gravel, qualities of, 125.
Gravel road, the, 124-133;

care of, 187, 191.
Gumbo or buckshot soil, 114.

Highways, ancient imperial, 4,
5, 6-18.

Labor-supply affected by bad

roads, 59.
Land, increase in value due to

good roads, 57.
Legislation as to public roads,

22, 27, 38.
Loam, properties of on roads,

114.
Location of a road, advice as

to, 64, 80; importance of,

62, 80; value of surveys

for, 65.

McAdam, J. L., biography of,
28.

Macadam or broken-stone
road, the, 134-162; care of,
194, 198; cost of, 161;
courses of stone in, 157;
drainage of, 152-155; first
in the United States, 31;
foundation for, 155; select-
ing materials for, 163-176.

Machinery and implements.

See BOAD-MAKING MACHIN-
ERY.

Maintenance of roads, 177-
236; American neglect of,
180; French system, 50,
180; importance of syste-
matic attention, 49.

Mediaeval ruin of the high-
ways, 18, 21.

Mudholes, treatment of, 93.

National Turnpike, the, 33.

New England Path, the, 31.

Office of Public Roads, origin
of the, 35; work of the, 36.
Oil for surfacing roads, 218.

Paths, construction of, 229-
240.

Pavements in old times, 7, 25.

Personal service on roads a
bad policy, 21, 44.

Peruvian road construction,
17.

Plans and specifications, rules
for making, 68, 71-78.

Plough, the, and its use, 104.

Policy of road administration
recommended, 40.

Population affected by condi-
tion of local roads, 59.

Post-service, ancient, 6; early
posts in the United States,
31.

Public roads: public owner-
ship necessary, 42 ; econom-
ics of, 54; financing, 57;
more than local institutions,
48.

Quarrying for road-material,
139-143.

Repair of public roads, 177-
206.

Roads in ancient times, 6-18.

Road-grader, the 103, 107,
148.

Road Improvement Associa-
tion, rules of, 200.

Road machine, the, 107-109.

Road-making, revival of in Eu-
rope, 20.

Road-making machinery, 101,
143, 147.

Road roller, use of the, 147,
158.

INDEX

263

Road sprinkler, the, 147.

Roadside, treatment of the,
207-214.

Roadway, preparatory clear-
ing of the, 98.

Rocks classified as road ma-
terial, 165; specific gravity
and weight of, 149; suitable
for macadam, 163; tests for,
172.

Rock asphalt as a binder, 225.

Roman roads, construction of,
10-14 j maintenance of, 14.

Sand and clay, directions for

mixing, 115, 117.
Band-clay road, the, 111-123;

care of, 185.
Sandy roads, treatment of,

121.
School attendance affected by

condition of the roads, 60.
Scrapers and their use, 102,

106.
Shade trees, selection of, 208,

211.

Snow, protection against, 210.
Spreader, the, 148.
Stone crushing, advice as to,

143-146.

Stone, first use in bridges, 5.
Subdrainage of roads, methods

of, 94, 96.
Sulphite liquor as a binder,

222.
Surveys for new or improved

roads, 65-78.

Tar for surfacing roads, 219.
Telearch, Greek, office of, 7.
Telford, T., biography of, 29.
Tile drains, how laid, 154.
Tolls, bad policy of, 22, 27, 33,

43; first collected, 6.
Trails, the forerunners of

roads, 3.
Tresaguet, biography and

work of, 23.
Turnpikes in the United

States, 30, 33.

Walks of cement or concrete,

233.
Weeds, grass, etc., harmful,

109.

Width proper for roads, 98.
Wind, protection against, 210.

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