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FEB 5- 1910

Road Preservation and
Dust Prevention

WILLIAM PIERSON JUDSON, M. Am. Soc. C.E.

Containing illustrated descriptions of the latest
methods and materials used in the United
States and in Europe for the preservation of
surface and the prevention of dust on roads of
broken stone, gravel or sand, with details of
costs and results, which are here for the first
time compiled and condensed into book form.

Cloth, 6x9 inches. 144 pages. 16 illustrations.
Price, $1.50 net.

THE ENGINEERING NEWS PUBLISHING COMPANY

CITY

ROADS AND PAVEMENTS

SUITED TO

CITIES OF MODERATE SIZE.

Fourth Edition, Revised.

WILLIAM PIERSON JUDSON,

Consulting Engineer

Member of the American Society of Civil Engineers
Member of the Institution of Civil Engineers (of Great Britain)

Member of the Massachusetts Highway Association

Member of the American Society of Municipal Improvements

Author of uRoad Preservation and Dust Prevention"

NEW YORK
The Engineering News Publishing Co..

LONDON
Archibald Constable & Co., Ltd..

1909

by
WM. PIERSON JUDSON.

Entered at Stationers' Hall, London, England,
1909.

CHAS. VAN BENTHUYSEN & SONS.

PRINTERS,
ALBANY, N. Y., U. S. A.

TABLE OF CONTENTS.

PREPARATION OF STREETS FOR PAVEMENTS—

Reduction of width. Drainage. Subdrainage. Rollers. Roll-
ing dirt roads. Wide tires. Pressure of traffic and of struc-
tures. (8 illustrations) Page 7

ANCIENT PAVEMENTS—

Comparisons. Stone wheel-tracks ; competition with first
railway. (2 illustrations) Page *7

MODERN PAVEMENTS—

Comparative loads. Cost. Pavements for steep grades :
asphalt; vitrified brick; creosoted wood block; block stone;
broken stone ; bituminous macadam. Crown of pavements :
Rosewater formulae of 1898 and 1902. Form of crown: for
macadam. Falls of horses on different pavements. Culverts :
kinds ; sizes ; costs. Curbs : kinds ; sizes ; costs. Car-track
construction. (4 illustrations) Page 25

CONCRETE BASE FOR PAVEMENT—

Need. Subgrade. Cement: simple outfit for easy tests ; fine-
ness; quickness; soundness; purity ; weight ; results. Mannei
of use. Aggregates. Sand. Proportions and mixing. Water.
Machine-mixing. Spreading and ramming. Monolith. Sur-
face. Setting. Wetting. Freezing : use of brine; limit of cold.
Cost. Portland. Natural. Extra work. Table, 36 cities.
(5 illustrations) Page 42

BLOCK-STONE PAVEMENTS—

Defects. Merits. Cost. Extent. (6 illustrations) Page 57

CONCRETE PAVEMENT—

Extent. Construction. Cost. Limitations. Page 64

WOOD PAVEMENTS—

Old. Cedar block. Modern. Australian. American kreo-
done-creosote ; creo-resinate ; cost. (5 illustrations) Page 66

IRON-SLAG BLOCK PAVEMENTS—

Method. Extent. Cost. Page 81

TABLE OF CONTENTS.

VITRIFIED BRICK PAVEMENTS—

Modes. Extent. Objections. Production. Characteristics.
Qualities. Tests. Examination in use. Construction : base ;
sand cushion ; joint-fillers ; expansion. On steep grades. Cost.
Guarantee. (8 illustrations) Pa8e 82

AMERICAN SHEET-ASPHALT, ARTIFICIAL AND NA-
TURAL—

Comparison. History. Artificial. Natural. Companies.
Sources. American artificial : materials and methods ; founda-
tion; binder ; wearing surface ; rolling. Steep grades. Crown.
Railway tracks. Cost. Guarantee. Causes of failures. Block-
asphalt; extent; cost. Comparative preferences, asphalt and
brick. (9 illustrations) Page 103

BITULITHIC PAVEMENT—

Characteristics. Details. Methods. Cost. Opinions. (4 illus-
trations) Page r3i

BROKEN STONE ROADS— (

Extent. Rock for roads. Tests of rock. Motor-trucks to haul
stone. Telford and Macadam: relative costs. Binder: mode
of use; quality; quantity. Maximum grades. Construction.
Subgrades of various kinds. Rock : crushing ; screening.
Base. Top. Thickness. Crown. Cost. Caution. Main-
tenance. Methods of repairs : raveling; rolling; ruts; clean-
ing; cost. Re-surfacing: methods; cost, (i 8 illustrations)

Page 138

INDEX— Page 189

PREFACE TO SECOND EDITION.

The local features of the first edition, having served their purpose,
have been omitted, and modifications have been made to show the
present applications of general methods, some of which have
changed since 1894. The most marked change during the past eight
years has been in the increased use of crushed stone for roadways of
macadam and of telford construction, on the improved streets of
villages and cities. A notable instance is that of the city of Greater
New York, which contains outside its parks eight hundred miles of
crushed stone roads built since 1894.

This general increase has resulted in part from the work begun in
1893 by the State of New Jersey, followed in 1894 by Massachu-
setts, in 1895 by Connecticut and in 1898 by New York. The
examples given by the governments of these States in building
highways by State aid and outside corporate limits, have led to
the building by the municipalities of similar roads within many cities
and villages, which have thus wisely profited by the experienced
methods of State officials.

The results have been an increasing extent of the best kinds of
roads of broken stone, and a growing knowledge of the methods
and machines by which alone can such roads be built and main-
tained. These are here described under the heading " Broken
Stone Roads," without however differing essentially from the
descriptions given in the first edition.

The grade of a city street is usually a fixed condition and not a
theory, and it is often difficult to decide which is the best pavement
for a fixed steep grade in a given climate, or how steep a grade will
give good results with a given pavement. Tables of actual instances
are given in order that engineers may know where to find condi-

PREFACE TO SECOND EDITION.

tions similar to their own, and where they may examine certain
pavements in actual use. To watch the traffic using a steep paved
slope or to examine its condition during a sharp shower or after a
heavy rain, will suggest points as to the proper grade and crown
which will be worth any amount of theorizing as to maximum
grades.

The sections entitled respectively " Concrete Base," " Block
Stone," " Wood," " Vitrified Brick," " Asphalt," " Bituminous mac-
adam '' and " Broken Stone," are made to accord with the latest
records of methods and costs, using illustrations and tables for
brevity. These records have been obtained from personal practice
and investigation and from the publications and discussions of the
several Societies of Civil Engineers, from the reports of the officials
of States and Cities, and from the columns of Engineering News,
The Engineering Record, Municipal Journal and Engineer, The
Engineering Magazine and Municipal Engineering, and also directly
from many civil engineers in addition to those whose names are
mentioned. The uniform courtesy shown by civil engineers, both
in the United States and abroad, in cordially meeting inquiries
regarding their works, methods and results, and in freely giving all
desired information, is a marked and peculiar characteristic of the
Profession.

The^c statements of facts and opinions are meant for those who
wish to profit by the varied experiences of practical road makers.

WM. P. J.

OSWEGO, NEW YORK, -
May i, 1902.

PREFACE TO FOURTH EDITION.

This edition is prepared in response to the continued call for the
book as a guide to the building of rural highways as well as of city
pavements. Additions and changes are made on pages 64, 81, 100,
in, 112, 114, 119, 120, 121, 147, 149, 179 and 187, to make the
book accord with the latest practice. WM. P. J.

OSWEGO, NEW YORK,
February i, 1909.

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CITY ROADS AND PAVEMENTS

SUITED TO CITIES OF MODERATE SIZE.

The extent of street-surface in the cities having a
population of fifty thousand or less is usually such that
only a portion can be paved or improved at any one
time, and it is therefore necessary to carefully study
the local conditions existing in any given city in order
to determine which of the various kinds of pavement
are best suited to the existing conditions of slope and
of traffic and of treasury, and to the local supplies of
proper materials.

REDUCTION OF SURFACE TO BE PAVED.

In cities which have always had dirt roads, the actual
width of roadway is usually much greater than is
needed for the traffic, and the subject should first be
studied with a view to reducing the area to be paved
by widening the bermes and the sidewalks on each side
of the street, and thus narrowing the roadway to a
width no greater than the traffic demands. Many
cities have 42 feet to 45 feet width of dirt roadway on
residence streets where 26 feet and 32 feet would be an
ample width between the curbs of the same streets

CITY ROADS AND PAVEMENTS.

when they are paved ; 32 feet is the width most often
used. The beauty of the streets will be much improved
by such change and by forming on each side of the
street a wider grassy berme outside of a row of trees,
and this change will also give room for wider sidewalks,
which in many cases are much needed. These wider
bermes can usually be formed from the worn earth
and sand which must be scraped from the surface of the
existing old roadways before attempting to form new
ones.

DRAINAGE OF ROADWAY.

Having determined the proper widths of roadway of
the various streets, their grades should be most closely
studied in order to get the best results with the least
change of existing grades ; it should be considered that
the proposed pavements with their curbs, crossings,
manholes and catch-basins will be, or should be, per-
manent structures and they should be located carefully.

Before paving any street, there should be in place a
complete system of sewers and of pipes for water and
for gas with service-branches to every lot on both sides
of the street, and writh manholes to give access to the
sewers, and with catch-basins so arranged as to take
the storm-waters without blocking the sewers with
street-waste and silt, which can readily be prevented
from entering the sewers by the use of recent improve-
ments in catch-basins. In designing these sewers, and
in considering whether existing sewers are sufficient, it
must be remembered that the proposed pavements will
bring the storm-water into the sewers more quickly and
that larger capacity will be needed to carry the in-
creased flow.

SUB-DRAINS.

Careful consideration should also be given in order
to decide whether the local conditions make it best to
provide subways for electric wires.

The thorough drainage of such streets as have been
naturally muddy in spring and in fall, must be provided
for before any method of paving or surfacing is consid-
ered. The natural earth is the real roadbed which
does the work, and it can only support the pave-
ment— of whatsoever kind it may be — by being
kept dry.

In most of the cities, a portion of the streets have
good grades and will drain naturally if rightly formed ;
and it is the streets running at right angles to these
which will be most difficult to drain, especially if they
are on a hillside having springs in the subsoil, which
must then have sub-drainage by tile drains before any
form of surface or of pavement will be of permanent
value or effect.

There are many such streets on which rain water
now stands until it evaporates. On the ordinary street
in northern cities, the direct rainfall between fence-
lines per mile, is equal to 30,000 tons or 8 million
gallons of water every year, and there are many streets
where this water has been left to evaporate or to soak
into the ground.

SUB-DRAINS.

Any such roadbed, where, from any cause, water
naturally stands and forms mud, must be thoroughly
sub-drained. To put broken stone, or gravel, or any
valuable material of any kind upon a bed of earth and
ashes which rain will convert to mud, is to throw away
both money and material.

CITY ROADS AND PAVEMENTS.

The sub-drains should consist of lines of two inch
to four inch porous tile, or four inch to six inch vitri-

fied tile laid with open joints ; one line on each side
of a level road which receives drainage from both sides,
or one line only on a hill-side road, this being put

on its up-hill side to intercept ground-water from the
higher ground. These tiles should be placed on an
accurate grade, a foot or more below the bottom of the
gutter, next to the curbs, away from tree-roots and
below frost, in order to lead the ground-water to the
catch-basins or road-culverts, from which it will run to
the sewers or outlets with the surface-water from the
pavement.

The provision of this sub-drainage should be the
first move toward making any permanent roadway on
a flat street.

ROLLING THE EARTH ROADBED.

For any method of road-making or of paving which
may be adopted, a steam roller of about ten to twelve

ROLLING THE EARTH ROADBED.

tons weight is requisite in order to compact the earth
roadbed so that it will sustain the wheels which will
pass over it. As well try to make the bricks of old
Egypt without straw as to try to make the roads of
to-day without a heavy steam roller. Every fully
equipped road-builder has one or more. There are few
cities which have not made some effective efforts to
have good roads, and those which have done so know
from experience that no good results can be expected
until the proper tools are used. For any system of
pavements or of roads, a steam roller is the thing first
needed, and no contractor's bid should be considered
unless he agrees to provide and use a steam roller of
at least ten tons weight so proportioned as to distrib-
ute the weight on wheels which cover and compress
the full width of its track.

The undulations and hollows which may be seen in
the surface of many existing pavements are the direct
results of the lack of a proper roller which would first

Traction engines which leave an uncompressed strip in the middle of their track
are not suitable for road-rollers and several attempts to use them in road-building
have been costly failures.

I I

CITY ROADS AND PAVEMENTS.

have disclosed the presence of the soft places in the
earth roadbed, and then would have packed the grad-
ing-material into them, so that the finished pavement
would have had a solid and permanent foundation and
a regular surface.

GOOD EFFECT OF ROLLER ON DIRT ROADS.

Especially valuable would such a roller be for cities
having great extent of dirt roads, which could be formed
by use of the wheeled scraper and then rolled to a
smooth, hard surface, furnishing fine roadways during
the summer months until the fall rains make them
muddy. By rolling the roads as they freeze, towns can
make their earth streets smooth for the whole winter
and so that a few inches of snow will give good
sleighing.

Nearly a mile per day of temporary, summer road-
way can be made at small cost by a scraper, sprinkler,
and steam roller working together.

The sprinkler should be selected to have six-inch
tires with rear axle two inches longer on each end than
the front axle ; it should be built without a reach so
that it can be turned without digging holes in the
roadway, and should have a sprinkler which is under
the perfect control of the driver.

The roller should be selected to be of not more than
ten or twelve tons actual weight when loaded, so that
it can cross ordinary bridges safely and can roll streets
without crushing buried pipes. The roller should be
tested to see that it can climb ten per cent grades when
they are covered with loose stone, and also that it can
hold its steam-pressure during continuous operation,

PRESSURE OF TRAFFIC.

and it should also have a record for durability under
rough usage.

WIDE TIRES ON WHEELS.

To supplement the good effect of a roller on the dirt
roads, which are now cut by narrow tires, the use of
wide tires on heavy wagons should be required. The
following is a practicable way of initiating such a rule :

Let the Board of Public Works of any city order that
no wagon will be employed upon city work unless it
has four-inch tires on its wheels, with the front axle
eight inches shorter than the rear axle. This will
make each wagon equal to two eight-inch rollers.

Let the same order be applied to ice-wagons and to
public carters, as a condition of issuing a license. A
future date could be published at which all heavy
wagons doing business in the city, including farmers'
wagons from the surrounding country, shall have such
wheels. This publication will stop the sale of narrow-
tired wagons, which will gradually be displaced by
those with wide tires, when the roadways of the vicinity
as well as of the city itself, will no longer be so deeply
cut and furrowed as now by the pressure of traffic.

PRESSURE OF TRAFFIC.

It is only necessary to consider the great pressure
which ordinary traffic will put upon the roadbed in
order to realize that no pavement can keep its form
and its regular surface unless the earth roadbed, on
which all the pressure finally comes, has been perfectly
compacted before the pavement is laid over it ; for the
pavement, of whatever material it may be, is merely a

CITY ROADS AND PAVEMENTS.

COMPARISON WITH PRESSURE OF STRUCTURES.

more or less rigid surface which receives the pressure
of traffic and distributes it to the supporting earth.
For instance, the ordinary coal wagon, weighing 1,200
pounds, draws two tons of coal and has tires two inches
wide. As the wagon stands on the pavement, the
bearing surface does not exceed a length of one and
one-half inches on each wheel ; the four wheels thus
standing upon a total surface of twelve square inches,
with a total pressure of 5,200 pounds, or 433 pounds per
square inch, and this is applied with a rolling pressure
which is most destructive.

COMPARISON WITH PRESSURE OF STRUCTURES.

The degree of pressure which this puts upon any
pavement will be best appreciated by comparing it with
the pressures per square inch upon the clay, sand, or
earth underlying the foundations of some well-known
great structures.

The Cleveland viaduct 14 to 23 Ibs. per sq. in.

The 1 894 London tower bridge 21 "

The sixteen-story office buildings of Chicago 21 "

The Memphis bridge piers 22 "

The Albany capitol 28

The Brooklyn bridge anchorage 56 "

The earth supporting these structures is, of course,
compressed to the greatest degree in its natural forma-
tion, but the average pressure of these structures is less
than one-sixteenth of the pressure concentrated on an
ordinary wagon wheel.

CITY ROADS AND PAVEMENTS.

Ancient Roman Road,

Early Eighteenth Century Road.

Late Eighteenth Century Road.

Modern Macadam Road.

RELATIVE THICKNESS OF ANCIENT AND MODERN ROADS.

ANCIENT PAVEMENTS.

Paved highways were built by the Romans through
Europe and throughout the Empire two thousand to
twenty-two hundred years ago, and portions of these
pavements still endure. Many of them have been
examined to learn whether the details of their con-
struction included features which are now worthy of
imitation.

It is found that the locations of these roads were
usually made in the simplest manner, ignoring natural
obstacles and directing the course by straight lines
toward prominent landmarks. Upon the lines thus
defined, the width of the proposed roadway was then
marked by two parallel furrows which were eight feet
to twenty feet apart according to the importance of the
highway. Between these furrows all unstable materials
were excavated, usually to a depth of about three feet,
and in this undrained trench the road materials were
placed in more or less regular layers.

The statumen, or base, was formed of one course, or
sometimes of two courses, of large flat stones laid in
lime mortar, and was usually about fifteen inches thick.
Upon this was formed a Q-inch course of small frag-
ments of stone which were embedded in sufficient lime-
mortar to fill their voids, and which thus bound
together the tops of the large stones of the statumen;

CITY ROADS AND PAVEMENTS.

upon this, the nucleus was formed of fragments of
gravel, stone, pottery and brick mixed with lime-mor-
tar to form a concrete, which was consolidated by ram-
ming, and was made about six inches thick. Upon
this the summa crusta (top crust) or pavimentum (hard
surface) was formed of closely-jointed, irregular stones,
which formed a mosaic about six inches thick, the top
of which was practically on a level with the adjoining
natural surface of the ground.

In and near the cities the pavimentum was formed
of larger irregular blocks of basalt, or porphyry or lava,
two to two and one-half feet in length and width and
twelve inches to fifteen inches in thickness, which were
dressed and fitted together with extreme accuracy and
were bedded in cement.

In a general way there were thus used various ma-
terials and varied methods, none of which showed any
attempt at drainage of the subgrade, and all of which
were wasteful of the materials and labor, which then
cost nothing but the lives of captives, who were forced
to build these highways for the armies of their
conquerors.

The results were roads which were remarkable for
their strength and durability and for little else. If
anyone were so unwise as to attempt to build similar
roads now, the cost would be from four to eight times
the present cost of our most expensive modern pave-
ments which are, in every way, better for modern uses,
and upon which the cities of the United States are
estimated to have expended half a billion of dollars.

STONE WHEEL-TRACKS.

This peculiar form of stone pavement has long been
in use in the midst of the roughly paved streets of

STONE WHEEL-TRACKS.

many Italian cities and towns, and in some of the
largest Scotch and English cities, which facts probably
suggested its use on the Albany and Schenectady turn-
pike in 1833, when wheel-tracks, which are still in use,
and which are here shown by a photograph taken in
1901, were built on two miles of the worst parts of this
main highway to the West, and which were later
made to cover the dry and sandy parts of the fourteen
miles between the two cities.

There are, in 1902, no memories among the oldest
residents along the road and no published accounts in
local histories, of the origin and details of this interest-
ing pavement, and those which are here given Were
only found by search amidst a mass of old letters and
papers which were saved from an abandoned gate-
house by Wheeler B. Melius Esq. of the Albany His-
torical Society.

The turnpike itself was opened to travel in 1805, be-^
ing made twelve feet wide of gravel at a cost of $8,400
per mile. After ten years of attempts to maintain this
gravel road under the traffic of many heavy narrow-
tired wagons drawn by four or six horses, a "sunken
pavement " of cobbles was built on the dry and sandy
parts of the road, and broken quarry stone to the depth
of twelve inches, was " bedded " on the wet and clayey
parts, the edges being " bonded " by lines fifteen to
sixteen feet apart, of small boulders twelve inches to
twenty-four inches in diameter embedded in the earth
along each side. Under date of January 8, 1831, the
President and Directors of the Turnpike Company
reported to the Legislature that they had "hitherto
been unable to render said road hard and solid and to
keep the hard materials (gravel, broken quarry-stone

CITY ROADS AND PAVEMENTS.

and cobbles) on the surface of the earth." In April,
1831, strenuous protests were made by the stockholders
of this Turnpike Company, Chancellor Kent among
others, against the effect of the charter granted in 1826
to the Mohawk and Hudson Railroad Company, on the
ground that

" Should the Rail Road Company succeed, their operations will
necessarily diminish materially the tolls of the Turnpike Company,
and thus sap the consideration upon the faith of which the latter
have constructed their road."

Referring to the application of the Railroad Com-
pany for leave to run a side-track into the heart of
Albany, Chancellor Kent wrote from New York under
date of April 7, 1831 :

"If that would not be an interference with the rights of the
Turnpike Company, then nothing would be an interference short of
plowing up the Turnpike Road."

It was feared that the Railroad might eventually dis-
place the stages, the tolls from which formed a large
portion of the revenues of the previously-chartered
Turnpike Company, then amounting to $5,137 per
annum ; one-third of which was paid out to gate-
keepers and overseers and the balance was expended
in repairs and occasional small dividends : the tolls
were levied on a peculiar system by which a four-horse
stage paid 43^ cents to enter upon the road at either
end and the same amount to leave it, or 87 cents for
each single trip.

The steam railroad was, however, built, and was
opened to operation on September 12, 1831, as the first
exclusively passenger railroad in the world. The
handling of freight by the railroad was not begun till De-

STONE WHEEL-TRACKS.

cember 6, 1832, as detailed in a letter from the manager
to the president, when three cords of wood, making
two car-loads, were taken to Albany, and were the first
freight carried on what is now the New York Central
Railroad. In order to compete with the railroad, the
Turnpike Company then made many efforts to arrange
to build another railroad of their own along the side of
the turnpike,* and the failure of these efforts resulted
in deciding, in 1832, to lay the "stone rails," of which
twenty thousand linear feet were brought from Whalen's
limestone quarries at Flint Hill, eight miles up the
Mohawk valley from Schenectacly, and were laid in
1833 and 1834, and extended later. Sections of this
stone wheel-track, in some cases half a mile or more in
length, are still in good condition and in daily use, as
shown in the photograph made in 1901.

The " stone rails " were made four inches thick and
were roughly but eighteen inches to twenty-four inches
wide, of any length from two to eight feet, with square
ends to be laid close together and with both faces flat
to permit of turning over when worn. The slabs now
show a concave surface worn one to two inches at the
center. They were bedded in the gravel and broken
stone of the roadway, by two men at the rate of 125 feet
per day or one and one-half cents per running foot, the
cost of the stone delivered ready to lay being thirteen
cents per running foot. This made the wheel tracks
cost $1,530 per mile while the cobble paving two feet
to three feet wide between the tracks and five feet wide
on each side of the tracks cost $1,610 per mile: Form-
ing the roadbed cost $i 60 per mile, or a total of $3,300
per mile completed. A few slabs which have been

* Finally accomplished in 1901-2 by building a double track electric road.
The construction of a macadam Voad, in place of the stone wheel-tracks and
cobbles, was begun by the State in 1905.

2 I

CITY ROADS AND PAVEMENTS.

5 ft. of lars;c roblile pavement

ROAD FROM ALBANY WEST TO SCHEXECTADY, X. Y., 1901.
Built by Turnpike Company in 1834.

Sin. wide, 3 iu. deep

ROAD WEST FROM KINGSTON, ULSTER Co., N. Y., 1902.

Built by Turnpike Company in 1862.

STONE WHEEL-TRACKS.

broken have from time to time been replaced by old
blue-stone curbs from Albany.

About 1862, a system of similar wheel-track roads
was begun in Ulster County, N. Y., when Davis
Winne built a blue-stone track-way as a toll-road from
Kingston eight miles up the Delaware and Ulster
Valley to the blue-stone quarries in the Catskill moun-
tains. This proved to be so successful that branches,
and other roads of the same sort, were soon built and
are still in decreasing use.

The ease of traction on these smooth slabs led to
an increase of the loads drawn upon them, until eight
tons has been and is an ordinary load for two horses to
bring from the quarries in the hills to the wharves at
Kingston and Rondout. Loads of twelve to fourteen
tons drawn by three horses are now of daily occurence,
and loads of seventeen tons actual weight have some-
times been drawn by four horses : all loads being
weighed to determine the tolls.

These great loads were formerly carried upon nar-
row tires of one and one-half to two inches which
speedily cut furrows in the hard stones, so that the
slabs six to eight inches thick were cut through in

o o

three or four years and required renewal. Along the
roadsides are now many such slabs cut nearly through
and laid aside, while all the slabs which are in use show
furrows ranging from one to five inches deep and three
to four inches wide.

A railroad now parallels and crosses this highway
reaching the quarries or passing near them. Wide
tires, which are required in the river cities and towns,
are used on all wagons carrying these loads, so that
four-inch slabs of blue-stone are now used for renewals

CITY ROADS AND PAVEMENTS.

of the wheel-tracks and cost ten cents per running foot
of slabs twenty-four inches wide. The actual cost of
the original wheel-track road built in 1862 was about
$3,000 per mile ; the high prices induced by the War
increasing the cost fifty per cent over the contract-price
made in 1861.

MODERN PAVEMENTS.

Comparative loads. — In considering the desirability
of the different road-surfaces and pavements, it may be
noted that a team drawing one ton on a good dirt road
can, with the same effort, take two tons over a good
macadam surface. Passing from this to a good block-
stone pavement, six tons could be drawn as easily, and
this load can be increased to eight tons on good wood-
block or new vitrified brick, or to ten tons on a bitu-
minous macadam or an asphalt pavement.

COST OF PAVEMENTS.

The following table shows the conditions and costs
in 1894 in the 32 cities named, 8 of which had wood-
block pavements, 27 of which had sheet-asphalt pave-
ments, and all of which had block-stone, six having
sandstone, and the rest granite. The conditions and
costs in 1901 are shown in detail in the several
chapters.

CITY ROADS AND PAVEMENTS.

TABLE.

CITY AND STATE.

BLOCK-STONE.

SHEET
ASPHALT.

WOOD.

Granite.

Sandstone.

Cedar-block.

Cost,
Sq. Yard.

Miles.

Cost,
Sq. Yard.

Miles.

Least
Cost.

Albany N. Y

$2 90

3 37
i 49

3 9°

2 33

$3 12
2 75
3 °°
3 3°
3 oo

3 50

2 90

3 co
2 54
2 35
3 20

2 Is

2 80

2 93

2 75

\llegheny Pa

Atlanta, Ga

Boston, Mass

4
II

ISO
24

Brooklyn N Y

Buffalo, N. Y

$3 25

Chicao-o, 111.

3 °°
4 20

3 7i
3 4°
4 25
2 74

648

$1 10

Cincinnati, Ohio

Denver Col.

Detroit Mich

26
43
47
63

1 50

i 35
i os
76

Kansas City Mo.

2 90

Milwaukee Mis

2 37
i 67

2 40

4 75
3 50
2 32

Nashville Tenn.

New Orleans La

8
52
23

3 65
3 oo
2 68

New York N Y

Omaha Neb

i 52

Oswego N Y

2 45

Philadelphia Pa

2 4I

2 38
2 OO
•j 2<C

2 5°
3 35

Pittsburo- Pa

Portland Me

Providence R. I.

265

2 60

Rochester N Y

(I 90 £

( 3 °° 5

2 00
2 05
I 15

3 56
3 20

3J C

St Paul Minn

2 70

2 45

2 50

i 9^X

3°

I IO

3 oo

Toledo Ohio

Utica N Y

2 50

125

2 25

Wilmington, Del

2 08

Average of prices

$2 90

$2 71

$2 8l

$i 19

PAVEMENTS FOR STEEP GRADES.

In selecting a pavement for a given street of which
the grade cannot be improved, the choice will often be
limited by the fact that the grade is too steep to permit
the use of a pavement which might otherwise be
preferred.

PAVEMENTS FOR STEEP GRADES.

The most useful information on the subject can be
obtained from the teamsters and horsemen of cities' in
which different pavements on varying grades have
been in use. If it is generally agreed that certain
pavements are shunned by teamsters because their
horses slip and fall when going down a certain street
with a load, it will evidently be unwise to repeat the
construction of the same kind of pavement with equal
slope in a similar climate.

Under the headings of "Asphalt," "Brick," and
" Broken Stone," there are given numerous instances
of extremely steep grades upon which these pavements
are actually built in various cities named. Examina-
tions of these may furnish to the observer conclusive
reasons for or against copying them, or may suggest
changes in detail which would give better results. In
examining these steep grades, it should be borne in
mind that the selection of a pavement for a given street
may have been made directly or indirectly by the prop-
erty owners, who have not necessarily chosen the pave-
ment best suited to attract traffic, but who, preferring a
quiet street, sometimes select a pavement which traffic
will shun.

Sheet Asphalt. — The practical limit of slope for busi-
ness streets paved with asphalt is 4 feet per 100 feet,
though any slope steeper than 3 feet per 100 feet is
not advisable on a main thoroughfare.

On residence streets grades as steep as six per cent,
are common, and much steeper ones often occur as
shown on page 1 18 : The residents accepting the incon-
venience resulting from a few days of icy roadway
because of the many and great advantages during the
rest of the year.

CITY ROADS AND PAVEMENTS.

On semi-business streets having steep grades, it is a
common and good arrangement to lay a sixteen feet
asphalt roadway in the center, with an 8-foot strip of
block-stones or chamferred bricks, or grooved-joint
wood blocks, on each side. In Syracuse, N. Y., on East
Genesee street, and on Bellevue avenue, this was done
in 1897-8, using Medina sandstone blocks. In some
cases where this has been done, the asphalt has been
used almost exclusively.

Even on flat streets, however, in cold, misty weather,
horses slip badly, so that in Washington it is common
to remove the shoes from horses in winter because the
hoofs slip less. In Brooklyn, on Christmas, 1901, many
delivery-wagon horses were seen with burlaps tied over
their hoofs to give foot-hold on the asphalt.

There will be parts of two or three days during most
winters when this difficulty will occur with both asphalt
and brick, both on steep and on level streets unless
sand is strewn.

Vitrified Brick. — No complaints are made of slip-
ping upon grades of five per cent, but these will be more
or less slippery as soon as this slope is exceeded, with-
out regard to ice. Observations show that horses
begin to slip on brick as soon as the grade reaches six
per cent, and that for any slope over five per cent it
will be advisable to use special brick having a beveled
top affording a foot-hold in the joints, which should be
filled with asphaltic cement and sharp sand. With
this precaution vitrified brick can be used on slopes as
steep as are shown on page 98.

Creosoted Wood Block. — The same general condi-
tions apply to these as to asphalt for the grades less

PAVEMENTS FOR STEEP GRADES.

than three per cent, provided sharp sand is strewn over
the surface when needed, as for asphalt.

For grades steeper than three per cent, the special
grooved joint here shown in detail is filled with
asphaltic cement and coarse sharp sand, and this gives
as good a foot-hold as grooved brick.

Block Stone. — This may be used in its ordinary form
upon slopes less than ten per cent, but for this slope
and greater, the blocks should have chamfered tops
and special joints to give better foothold. The best
manner of construction is detailed on page 61.

Broken Stone. — The maximum grade of macadam is
fixed rather by the difficulties of maintenance than
by conditions which govern the other pavements.
Any grade steeper than five per cent offers increased
difficulties from the wash of storm-water, although
many instances are given on pages 164-166, where
these actual steep grades were accepted by the engi-
neers who built these roads as being unavoidable
features which would have been changed if possible.

CITY ROADS AND PAVEMENTS.

Concrete. — On any slope, and even on a level street,.
a Portland-cement concrete surface needs to be grooved,
as described on page 64, in order to give a good foot-
hold.

Bitulithic. — This pavement, which is a bituminous
macadam and is described on page 131, has proved
during extensive use since 1901, to be specially adapted
to meet the difficulties which have heretofore attended
or prevented the use of broken stone on steep grades.
While it presents a surface which gives secure foot-hold
on steep slopes, it does not afford any chance for toe-
calks to loosen it or for storm-water to gully it.

CROWN OF PAVEMENT.

The ideal road-surface for a rainless climate would
be flat, but the practical road-surface for all weathers
must be curved or " crowned," in order to quickly shed
water to the gutters. This is the sole reason for giv-
ing a " crown," and it is therefore logical to reduce the
amount of curvature when the slope of the street gives
the needed drainage.

To suit the crown to the slope, engineers have made
frequent use of the formulae devised in 1898 by Andrew
Rosewater, M.Am. Soc. C. E., city engineer of Omaha,
Neb., by which the crown is computed for any width
and any grade : the amount of crown decreasing as
the slope increases.

The 1898 formula are as follows :

For Brick, Stone and Wood block = C = i6oo (20— /)

For Sheet-asphalt, C = ^ (g-f)

C = crown of pavement in feet,
W = distance between curbs in feet,
f= grade of street in feet per 100.

CROWN OF PAVEMENT.

STANDARD CROWNS BY FORMULA OF 1898.

FOR BLOCK-STONE, BRICK AND WOOD-BLOCK

DISTANCE

Crown given in hundredths of feet.

CURBS

Grade of street in feet per hundred.

in feet.

LEVEL.

tr.

2 2

a; *-•

~ o

£ £

S°

3°

°00

n<£

5°

oo og

rt C

J* S*

7°

£°

IOO

9°

7°

DISTANCE

BETWEEN

CURBS

FOR SHEET-ASPHALT
Crown given in hundredths of feet.

Grade of street in feet per hundred.

in feet.

LEVEL.

£ «

i-C (i)

*1 "

f &

0 in

l£

5°

9°

7°

5°

- §

}_, IH

I05

7°

o
u

IJ3

IOO

5°

120

107

CITY ROADS AND PAVEMENTS.

1902 Formula. — Observations since 1898 have con-
vinced Mr. Rosewater that American sheet-asphalt
pavements should have the maximum crown practi-
cable for traffic, as a means of protection against the
standing of water in the small surface depressions.

Observation also suggested to him an increase of
crown of all pavements on various gradients because,
under the 1898 formulae, the pavements on grades
varying from three to eight per cent failed to shed
water to the gutters quickly enough to prevent freezing
in sleety weather, or to avoid its spreading in warm
weather.

To meet these objectionable conditions, radically
different formulae have been devised in 1902 by Mr.
Rosewater as substitutes for those of 1898.

The 1902 formula are as follows :

For brick, stone-block, wood-block and com-") W (I00 _ 4/)

pressed European rock-asphalt, J 6000

For American sheet-asphalt \^ W (I00— 4 /)

(composed of sand and asphalt or of compressed
natural sand-rock), - ...

C = crown of pavement in feet,
W = distance between curbs in feet,
f = grade of street in feet per i oo.

CROWN OF PAVEMENT.
STANDARD CROWNS BY FORMULAE OF 1902.

DISTANCE

BETWEEN

FOR BLOCK-STONE, BRICK AND WOOD-BLOCK
Crown given in hundredths of feet.

CURBS
in feet.

Grade of street in feet per hundred.

Level.

5°

100

1 08

104

IOO

117

112

107

103

125

120

105

IOO

133

128

123

117

112

1 06

IOI

DISTANCE

BETWEEN

FOR SHEET-ASPHALT
Crown given in hundredths of feet.

CURBS
in feet.

Grade of street in feet per hundred.

Level.

IOO

1 06

IOI

120

I IO

1 06

IOI

130

125

120

114

109

104

I4O

r,S4

I2Q

123

118

112

1 06

IOI

ISO

144

138

132

126

120

114

108

102

1 60

154

147

141

134

128

122

109

IO2

CITY ROADS AND PAVEMENTS.

Under the heading of "Asphalt," pagenS, and
" Brick," page 95, will be found the record of the actual
present practice for crown on level grades and 30 feet
width in the cities named.

Form of Crown. — The form of crown should be a
parabolic curve nearly flat at the center, for traffic, and
sloping more quickly toward the sides, for drainage.

When the amount of crown has been computed
from a formula or a table, or when an experienced
engineer has preferred to determine it arbitrarily,
as is very often well done, the form of the curve can
be determined thus for any width or crown : divide
the space from center to curb into twelve equal
parts. Take the center ordinate, or total "crown,"
as unity; then the successive ordinates, measured up
from the base-line, will be: At center, i.oo, .99, .97, .94,
•89, -83, -75» -66> -55. 44» -30, 1 6, .o at curb. Or
stretch a line from curb to curb on level with the
center, and measure clown the corresponding amount.
Thus if the width is 30 feet from curb to curb, and the
crown has been determined to be half a foot, the ordi-
nates measured down at intervals of i % feet will be in
inches and decimals. At the center o inches — 0.06,
0.18,0.36,0.66, 1.02, 1.50, 2.04, 2.70, 3.36, 4.20, 5.04,
6.00 inches at curb. This shows a side-slope of about
five per cent on the third next the curb. These fig-
ures may be useful in making a template for fixing
the curve of a pavement-surface, or for forming the
sand-cushion of a brick pavement as described on
page 95-

For Macadam, it is usual to consider that the con-
ditions to be met are reversed, and it being necessary
to prevent storm-water from following the road-surface,

S*vV

C ,0

E- "o

K |

K S

< &

C o

CITY ROADS AND PAVEMENTS.

the " crown " for macadam is increased as the slope
increases; one-half inch per foot being usual on level
grade, and a maximum of three-quarters inch per foot
on steep slopes, increasing to one inch on excessive
slopes. This produces in theory a ridge in the center,
with a straight slope of 5^ inches on each side for a
level 22 foot roadway. But in practice, the roller flats the
central " ridge " down, and produces a curve which is
flat in the center and slopes most at the sides, which is
the form desired.

FALLS ON DIFFERENT PAVEMENTS.

As to the relative liability to accidents from slipping
of horses' feet upon different pavements, observations
were made for Captain (now General) Francis V. Greene,
M. Am. Soc. C. E., during a period of six months on
thirty-six various streets in ten different cities, viz.:
New York, Philadelphia, Chicago, Boston, St. Louis,
New Orleans, Washington, Buffalo, Louisville and
Omaha. The result of these observations, and of
similar ones made by Col. William Hay wood, M. Inst.
C. E. in London, by George F. Deacon, M. Inst. C. E.
in Liverpool and by French engineers in Paris, were
read before the Am. Soc. C. E. on December 16, 1885.
Over 800,000 horses and 81,000 miles of travel were
observed in the ten cities of the United States, with
the result of showing that a horse may travel, for each
fall that occurs —

272 miles on wood-block pavement.

413 miles on granite-block pavement.

583 miles on sheet-asphalt pavement.
These results in the cities of the United States dif-
fer radically from those obtained for Colonel Haywood,

CULVERTS.

in London, where it was required that horses should
be smooth-shod, instead of having the sharp toe-calks
which are generally used in the United States, and
where European rock-asphalt is used instead of Trini-
dad asphalt and sand. The results observed in Lon-
don were —

446 miles on wood-block pavement.

132 miles on granite-block pavement.

191 miles on sheet-asphalt pavement.

CULVERTS.

To carry water beneath a roadway, culverts are
variously built of cast-iron pipes, of masonry, of concrete
and of double-strength vitrified pipe.

The bottom-line of culverts is usually fixed at the
bottom-grade of the side-ditches so that the available
height is limited, and large waterway is often obtained
by using two, and sometimes three, parallel lines of 18,
24 or 3O-inch pipes.

If the ditch drains a hillside having a southern
exposure, the midday sun of winter will supply a trickle
of water which will freeze at night, and under this con-
dition such pipe culverts will soon freeze solid and
sometimes burst.

For most conditions, box-culverts of rubble masonry or
of monolithic concrete with embedded expanded metal
in the covers, are much preferable to pipes, being less
ready to freeze and less liable to be damaged if frozen.

For equal areas of waterway and depending upon
the local conditions of stone-supply and freight rates,
the relative costs will usually be in the order first
named above.

When the span of a masonry culvert is two feet or
more and 6-inch to 8-inch cover-stones are used, they

CITY ROADS AND PAVEMENTS.

should be carried on suitable I-beams placed two feet
centers, in order to carry ordinary traffic safely. If
there is height enough a rough stone arch may be best
and cheapest.

CURBS.

Curbs should be set or re-set before beginning the
pavement of which they are a necessary adjunct. The
trench for the curb should first be cut and graded, and
sub-drained if needed, and if concrete foundation for the
curb is proposed, the curb-stones should be accurately
aligned and graded upon fragments of stone, around
and over which the concrete is to be formed and
tamped: the pavement-base, if any, and the pavement
itself being afterward formed against the face of the
curbs.

Curbs are used of various materials which are some-
what as follows for the different sections of the United
States ; there being noticed a general tendency toward
the use of concrete.

Kinds. — For the NewT England States, granite and
also concrete. For New York and the cities along the
Hudson and the coast, and for Washington in part,
"bluestone" (a tough sandstone) from Ulster county,
N. Y., and limestone and also concrete, of which there-
was built 202 miles in the Borough of Brooklyn during
1900. For central, southern and western New York,
and for adjacent Ohio and Pennsylvania, Oxford " bkie-
stone,"from Chenango county, N.Y., and Medina sand-
stone, from Orleans county, N. Y., and limestone, and
also concrete.

For the western and southern cities, granite, and
sandstone from Kettle River, Minn., and from Berea,
Ohio, and from Colorado, and also concrete, the latter

CURBS.

being much used in Chicago, St. Paul, and Cleveland.
Brick curbs are used with brick pavements in Louisiana
and Texas, and have been observed in two northern
towns in connection with brick gutters for macadam-
ized streets. These were special brick, 2%^-inch by
4^-inch by 8>£-inch, with one corner rounded, set
on end upon concrete with the edge toward the road-
way and showing 4^2 inches above the paved gutter:
they seemed to be poor substitutes for stone or con-
crete, as the material is unsuited for the purpose : this
opinion is confirmed by Willis Fletcher Brown, con-
sulting engineer of Toledo, Ohio, whose extended
experience with brick pavements is well known.

Sizes. — The dimensions of stone curbs vary in the
cities from sixteen to twenty-four inches for depth, five
to six inches for thickness, and three to five feet for
length. The top is always beveled to take the slope
of the sidewalk to the gutter.

Asphalt pavement"

Concrete curb is usually moulded in place in uniform
lengths, varying from four to ten feet, preferably five
feet, with }i inch joints formed by the removal of tem-
porary steel templates. It is often made in combination
with a 12-inch to 1 5-inch gutter, and it is recent and
good practice to acid a cast iron or a steel guard-strip^
or " rub-strip," anchored two inches into the concrete
by a 2-inch by ^-inch perforated web, and showing a

CITY ROADS AND PAVEMENTS.

rounded flat surface of i ^ to 2 inches on the outer top
edge, to protect against the impact of wheels.

Corners are usually curved on radii varying from four
feet to nine feet; the former preferred for streets of
moderate traffic.

COST.

Straight curbs set cost about as follows, with thirty
per cent to fifty per cent added for curves : —

Granite, 50 cents to 90 cents and in some cases
$1.25 per linear foot. Ulster or Oxford bluestone, 40
cents to 80 cents and in some cases $1.00 per foot.
Medina or Berea sandstone 35 cents to 70 cents.
Concrete usually costs from 40 cents to 50 cents, with
35 cents added for a combined gutter, though combined
curb and gutter have been built for 50 cents.

The prices vary widely with the freight-rates and the
local conditions.

CAR TRACK CONSTRUCTION.

When any of these pavements are to be built on a
street containing car-tracks, special attention must be
given to the reconstruction of the track and to the
details of the pavement next to the rails. The pave-
ment between the rails, and for two feet on each side
of them, should be built by the railroad company under
the plan and direction of the city engineer, or this
should be done by the city at the expense of the rail-
road, as in Rochester, N. Y. The methods there used in
1900 are shown in the picture here given. See p. 119.

This construction with heavy rails is necessary to
make the track-structure as rigid as possible, and this
is so well accomplished in 1901 that sheet-asphalt is

CAR TRACK CONSTRUCTION.

laid in actual contact with both sides of the rails, upon
which exceptionally heavy cars pass without cracking
the asphalt. This is seen at the best in Buffalo, N. Y.,
where the rails are electrically spliced in place, by
welding three-inch by one-inch by fifteen-inch steel
plates on both sides of each joint, forming continuous
ninety-pound rails for great lengths. Joints are cast
with molten iron with similar effect at Chicago, Brook-
lyn and Minneapolis, and many other cities where th'e
authorities and the railroads work together to get the
best results in their pavements.

TRACK AND PAVEMENT CONSTRUCTION, ROCHESTER, N. Y., 1900.

Medina sandstone block pavement on six-inch natural cement concrete base, and
trolley-railway track-construction on concrete foundations. Three-inch porous tile
beneath concrete and leading to sewers ; Ties two-feet centers, on concrete five
inches thick, with twelve inches of concrete between the ties ; Nine-inch full-grooved
steel girder-rails, bonded, resting upon the ties and upon twelve inches of concrete
between the ties.

CONCRETE BASE FOR PAVEMENT.

A concrete base, four to six inches thick, is desirable,
whether the wearing-surface is to be of asphalt, or of
creosoted wooden blocks, or of vitrified brick, or of
stone blocks. The wearing-surface will need repairs
and renewals, but a properly-made concrete base will
be permanent, and will always increase in strength and
solidity. It is specially needed wherever the street is
of recently made ground, or where it was formerly
swampy or unstable, or where traffic is expected to be
heavy, unless an old stone pavement is in place to serve
as a substitute.

SUBGRADE.

Before forming the subgrade to receive the concrete
base, all present and prospective sewer, wrater and gas
and subway connections should be made and extended
under the curbs, and all old and new trenches should
be tested with a ten-ton roller, and depressions should
be filled and wetted and tamped until solid.

HYDRAULIC CEMENT.

The manufacture of American Portland cements has
increased from one-third of a million barrels in 1890 to
a total of forty-eight million barrels in 1907, and the
manufacturers have meantime raised their standards,

CEMENT TESTS.

improved their products and reduced their prices to
keep pace with the growing demand for the highest
grades which were formerly only made abroad.

The differences in price between the high-grade
reliable cements and the low-grade uncertain ones are
comparatively small, and the poor cements will disap-
pear from the market when all engineers make tests and
are guided by the results.

Good natural cements are still much used,* as ap-
pears from the table at page 56, and they are better
than low-grade Portland cements, as well as being
cheapen

CEMENT TESTS.

The engineer of a small city will seldom have time
or outfit for the complete tests now usual on large
works, for which there are needed a special man with
an expensive equipment installed in a separate room.

The following described simple tests can be made
by the engineer himself, with an outfit costing not over
four dollars and which can be stored in a desk pigeon-
hole. The tests thus made will be interesting in them-
selves, and will be effective and convincing aids in
rejecting most bad cements which may be offered, and
will also have the preventive effect of causing manu-
facturers to send their lower grades of cement else-
where and to send only their best products to the places
where such tests are probable: —

First. — For fineness. — Sift three to four ounces of
cement through a standard test seive of 100 meshes
per linear inch. Reject cement of which ten per cent
by weight is retained on the seive. This is conserv-
ative and the limit may be made smaller, for many Port-
land cements are now in the market which will leave

* Seven million barrels made in U. S. during 1903, and five million barrels in 1904.

CITY ROADS AND PAVEMENTS.

less than four per cent. A test by 2oo-mesh seive with
a thirty per cent limit is desirable but takes time.

Second. — For qiiickness of setting. — Make a pat of
four ounces of neat cement adding one-quarter to one-
fifth its weight of water and making a putty-like ball
which can be dropped on the table and retain its form
without falling to pieces. Press this upon a three by
four inch glass plate leaving it half an inch thick in
the center and sloping to thin edges all around. Note
time required to take initial set. Reject cement which
sets in less than twenty-five minutes. It may take three
hours or more, but it will be better for paving if it sets
in one hour. The instant of " initial set " is determined
by noting when the surface will support a four-ounce
weight resting upon the smooth flat end of a one-
twelfth inch diameter wire ; *or better, by feeling of
the thin edge and noting when it crumbles.

Third. — For soundness. — Use the pat on glass above
described and note when it sets enough more to make
it difficult to indent it with the thumb nail, or when it
will support one pound on the smooth flat end of a one-
twenty-fourth inch wire, which may be considered as
indicating " a hard set." Then put the pat with its
glass plate over boiling water until the steam has heated
them, and then immerse and keep them in the boiling
water for three hours ; *or better, keep in the steam
only, for five hours. Reject Portland cement if_the
pat shows radiating cracks in the center, or shows blow-
holes on the surface, or curls up from the glass or cracks
at the thin edges. Good natural cements may fail to en-
dure this test (which is a severe one), and it may prop-
erly cause the rejection of some Portland cements which
would endure it after being " air-slacked " or " seasoned."

* These are the latest methods in use under the author's direction.

CEMENT TESTS.

Fourth. — For purity. — Provide a glass-stoppered
bottle of muriatic acid ; two shallow white bowls or two
half-inch by six-inch test-tubes, a glass rod and a pair
of rubber gloves. Put in a bowl or a tube as much
cement as can be taken on a nickel five-cent piece ;
moisten it with half a teaspoonfui of water ; cover with
clear muriatic acid poured slowly upon the cement
while stirring it with the glass rod.

Pure Portland cement will effervesce slightly and
will give off some pungent gas and will gradually form
a bright yellow jelly without any sediment.

Powdered limestone or powdered cement-rock mixed
with the pure cement will cause a violent effervescence,
the acid boiling and giving off strong fumes until all
the carbonate of lime has been consumed when the
bright yellow jelly will form.

Powdered sand or quartz or silica mixed with cement
will produce no other effect than to remain undissolved
as a sediment at the bottom of the yellow jelly.

Reject cement which has either of these adulterants.

Powdered slag mixed with cement unfits it for pave-
ment-work. The adulteration is indicated in the dry
cement (when coloring matter does not conceal it), by
a lilac tint, and it is also indicated on the surface of a
test-pat after drying, by brown and green and yellow
discolorations.

A chemical test will show the presence of slag if
made as follows :

Provide an ounce of mixture of methylene iodide
(C H2 I2) and benzine, in which the methylene (the
specific gravity of which is 3.2Q2 being the heaviest
organic liquid) is reduced to the specific gravity of 2.95
by addition of benzine. The methylene is uncommon
and costs a dollar an ounce.

CITY ROADS AND PAVEMENTS.

In a half-inch test-tube put half an inch of the dry
suspected cement and pour in a little of the mixture,
stirring to a thin grout. Then cork the tube and let it
stand. If slag is present, it will remain at top while the
cement will settle to the bottom. The separation can-
not be seen if coloring matter is present.

Coloring matter in any cement will show itself in the
acid test by giving a black or gray color to the resultant
jelly which would otherwise be yellow. The coloring
matter may, or may not, be injurious in itself, but its
presence shows that the manufacturer wished to dis-
guise the cement, which should be rejected, because
there are a plenty of good cements which need no
disguise.

Weight. — The several kinds of cement differ mate-
rially in weight and any cement that varies much
from these average weights should be examined
specially.

The standard barrel contains 3.65 cubic feet and the
standard bag is one-fourth of a barrel. The average
weight of a cubic foot of packed cement is : Portland,
104 to 114 Ibs. ; puzzolan, 90 Ibs. ; natural, 75 to 82 Ibs.
for Eastern and 70 to 72 for Western : The average net
weight of each per barrel being 375 Ibs., 330 Ibs., 300
Ibs. and 265 Ibs.

RESULTS.

These tests will be conclusive as far as they go,
and will cause the rejection of no good cements.
The makers of high-grade cements would not object
to these requirements and would not increase the price
because of them.

AGGREGATES.
USE OF CEMENT.

The cement in bags or barrels should be delivered
and stored in a tight shed two feet off the dry ground.

Blending. — The cement should never be used di-
rectly from any original barrel or bag, because there
may be more or less damaged or defective packages,
each of which would thus form a bad spot in the work.
This chance is wholly avoided by requiring that the
contents of five packages shall always be blended dry
in the cement-shed before any is sent out for use, and
that only this blended product shall be sent out of the
shed into the work.

This will not add to the cost, but will merely keep
the cement-man busier.

AGGREGATES.

The aggregates may be crushed from the cheapest
stone available, though the hardest and toughest is
preferable. Special care is necessary to see that the
stone, before crushing, is clean and free from mud
and clay. Stone unfit for masonry, or for macadam,
may serve the purpose when it shall be embedded in
the matrix of mortar in the concrete.

Crusher-dust as " sand.n--rT\\e total product of a
crusher passing through a 2 ^-inch screen will give the
best results, provided that the crusher-dust is consid-
ered as sand, and that proper allowance is made for its
presence after determining its quantity. If the stone
before crushing is not entirely clean, the crusher-dust
should be excluded by screening.

Clean gravel and sand may be used in lieu of stone
with the same provision as to the included sand.

CITY ROADS AND PAVEMENTS.

Where neither stone or gravel is available, as in the
middle West, fragments of brick or of furnace-slag are
often used as aggregates.

In any case, the number of cubic yards of loose ma-
terial for the aggregate will be twelve to twenty per
cent more than the total cubic yards of concrete ram-
med in place.

SAND.

The sand should be the sharpest and cleanest avail-
able, preference being given to pit-sand, of which the
grains vary from fine to course. It will be well worth
while for the engineer to examine the various sources
of supply, and to be as careful in its selection as in the
selection of the cement which is to be mixed with it.
In a recent case, sand, which seemed fairly good, was
washed and was then found to make concrete which
was one-third stronger than when the sand was used in
its natural state. Sand containing five per cent of
loam or of clay is common and should not be used until
washed. Two per cent will retard the set and per-
ceptably weaken the mortar.

PROPORTIONS AND MIXING.

The proportions measured in loose bulk should be
one part Portland cement to three parts sand to six
parts of the aggregate, or one part natural cement to
tw^o parts sand to four parts of the aggregate. (See
table at page 56.)

When the concrete is made by hand, the blended
dry cement, described on page 47, should be mixed on
a mortar-bed while dry with the due proportion of dry

WATER.

sand, until the color is uniform and no streaks of cement
can be noticed when the dry mixture is smoothed with
the back of a shovel. Water (equal in weight to eleven
to twelve and a half per cent of the weight of the sand
and cement for Portland cement and fifteen to seven-
teen per cent for natural cement) is then added gradu-
ally while mixing until plastic mortar is formed.*

Meantime the rest of the men are measuring, sprink-
ling and spreading the aggregate in a four-inch layer
upon the platform (for which a sheet of iron ten feet
square is the best), and on top of the layer is spread the
mortar, when the whole is turned with shovels by
four men wrhile two men work between them with
specially large hoes. This mixing is continued until
every face of every particle and fragment is perfectly
coated with the mortar, requiring hard work which
must be done rapidly.

WATER.

It is not important whether the mixing- water is pure,
but it should not be muddy.

The required amount of water should vary, as the
aggregates are more or less moist, so as to give a
uniform result, for to be either too wet or too dry is a
grave defect in concrete.

There is the widest difference of opinion among
engineers of large experience as to the degree of wet-
ness which gives the best results. All are agreed that
the surplus mortar must be brought to the surface by
ramming, after filling all voids. The effectiveness of
ramming will vary on different works ; the ease with
which the mortar is brought to the surface increases
with the amount of water, up to the condition where

* Strength of mortar increases with mixing, of which four-fold the normal
amount may add 25 per cent to strength.

CITY ROADS AND PAVEMENTS.

the concrete is so wet that no ramming is needed;
which is bad practice, but not uncommon.

'The best practice is to use the least water with which
the available rammers can be made to bring the mortar
to the surface. It is futile to try to secure this neces-
sary result by the persistent ramming of concrete which
has been mixed too dry, and which it were better to
remix with more and wetter mortar. There should
never be enough water to produce free grout, which
can drain away into the subgrade and be lost.

MACHINE MIXING.

Concrete is made better and more cheaply by any of
the various rotary mixers than it can ever be made by
hand. It is poor practice to depend upon shovellers to
proportion the materials, as is often done with continu-
ous and with gravity mixers. The proportions should
always be accurately measured. Mechanical mixers,
operated by steam power, are best adapted to large con-
centrated masses like dams, foundations and bridge-

READY TO LOAD. LOADED

abutments, but are not well adapted to forming a thin
layer spread over a large area, like a pavement-base.

This condition is particularly well met by a new
device known as a " dromedary mixer," which consists
of a two-wheeled cart of which the body is a cylinder,
which turns with the wheels as the cart is hauled
along.

SPREADING AND RAMMING.

The proper amounts of cement, sand, stone and
water, are put into the cylinder which is closed tightly,
and then the cart is hauled to the work where the per-
fectly mixed concrete is dumped in place and spread.

DUMPED

The machine is described and highly commended by
the city engineer of Baltimore, Charles E. Phelps, in
the Municipal Journal and Engineer, of December,
1901.

SPREADING AND RAMMING.

Set eight-inch boards from curb to curb, supported
on edge by stakes, and enclosing a space five feet wide,
within which spread the concrete in a loose layer about
7/{ to 7^ inches deep, for a six-inch base, so that a
one-yard batch will fill about one-third the width of a
thirty-foot pavement. Ram it at once vigorously until
all voids are closed, when the surplus mortar will come
to the surface and the mass will quake slightly under
the rammers.

Effective ramming is hard work at which a
workman should not be kept for more than an

CITY ROADS AND PAVEMENTS.

hour, when he should be changed to wheeling or
turning.

Monolith. — Each day's work must be a monolith.
The spreading and the ramming must be so done that
each successive batch shall be rammed before the pre-
ceding and the adjoining batches have begun their first
set. The stiffness of the concrete after ramming in
place must be such that the fresh mass will retain its
form and will not crumble when the boards are removed
preparatory to filling the adjoining space. Properly
managed there will be no lines between the batches,
which will all be merged into one mass.

Bond. — Each day's work can also readily be bonded
with the base previously formed, so that the whole will
be a monolith. Form the end of each day's work on a
steep two-on-one slope, or with a three-inch step and
vertical rises, and have the surfaces of the end show
voids between the fragments of embedded stone to
afford a good bond. When work begins the next day,
prepare a pail of thick grout of clear Portland cement,
and brush it freely over and into the voids of the
exposed end, just before dumping the fresh concrete
against it.

The result of omitting these small precautions, and
of making a flat slope at the end of each day's concrete-
work has been known to show, a year afterwards, in
well-defined waves of an inch or more in heigh tr ex-
tending from curb to curb of an otherwise perfect
asphalt pavement. These waves being resultants of a
slight expansion, or " growth," of the concrete which
slide upward at all the places, two hundred to three
hundred feet apart, where the concrete-work for each
day had ended.

SETTING.
SURFACE.

If it is desired to " float " the surface smooth, as is
required for pavement-base in Paris, and in Sidney,
N. S. W., and for curbs and gutters and for accurately-
cut wood-block pavements in the United States, the
surface may be formed of the matrix-mortar without
the embedded stone-fragments. It is of the first im-
portance that this surface shall be of the same mortar
as the matrix of the mass, and be placed at the same
time and thoroughly blended with it, and that it shall
not be made of a different or better kind or proportion
of cement, nor be spread afterwards as a plaster to cover
a porous or rough surface. Concrete which is consid-
ered to need plastering should rather be taken out and
replaced by good work.

SETTING.

When concrete has been rammed in place, it must
be kept entirely undisturbed until it sets firmly, which
should take from four to seven days ordinarily and
longer in cold weather.

Wet. — It is of vital importance that the concrete
should be kept wet during all this time, and that it be
sprinkled freely at night and morning, and be covered
from the sun by sand or canvass which will retain the
water.

It is a common thing to find experienced foremen
who fully believe that concrete should "dry out," and
many pieces of otherwise good concrete have been ren-
dered worthless by acting upon this idea which ignores
the plain fact that " hydraulic " cement requires water.*

Traffic of all kinds, both by foot or by vehicles, should
be kept from the concrete-base for at least a week if

* In 1906 there was widely published an article said to be from a well-known
road-builder, advising that the hydraulic cement of a concrete-base must have "an
opportunity to evaporate and solidifv and dry out." Young engineers cannot be
too strongly cautioned against such advice.

CITY ROADS AND PAVEMENTS.

possible, using planks to cover street-crossings where
passage-ways must be permitted.

FREEZING.

Portland. — For any concrete likely to be soon ex-
posed to frost, use Portland rather than natural cement,
and if possible avoid making concrete at all during cold
weather. Avoid very slow-setting cement for such
work, and especially avoid using sand or gravel con-
taining loam or clay, of which even two per cent will
greatly retard the setting of any cement with which it
may be mixed. Use a little more cement and a little
less water than in warm weather. Make special effort
to prevent the concrete from freezing, at least until it
takes its first set, and, if possible, for several hours
afterwards, and also prevent it from thawing after it
has frozen. While mixing, keep a fire burning in the
sand pile and another in the stone pile, and heat the
mixing- water.*

Brine. — Use brine by making a barrel of saturated
solution of salt, in which keep a layer of free salt show-
ing in the bottom ; put one-tenth of the contents of
this barrel, dipped from the bottom, into each barrel of
fresh water heated for mixing. It is useless to provide
easily broken salometers which the foremen will not
use, as this simple plan more readily provides a ten-
per-cent solution, which will retard freezing and which
will not injure Portland cement concrete, and which; in
some cases, will even increase its strength.

Limit. — Stop work when the cold reaches twelve
degrees of frost or 20° Fh. If each and all of these
precautions be observed, good results will be obtained,
but at greater cost than for work under the normal
conditions which are the basis of the following table.

* To heat water in a wooden barrel, screw one end of a lo-foot piece of 2-inch or
3-inch diameter iron pipe into the side of a barrel near its base. Cap the outer end
oi: the pipe, under and over which, on the ground, keep a small fire while the barrel
is supplied with water.

COST.
COST.

The present cost of concrete in cities was compiled
in 1901 in an unusually effective way by F. V. E. Bardol,
M. Am. Soc. C. E. and chief engineer of department
of public works of Buffalo, in the following table
which is republished from " Municipal Engineering."

These figures and this table do not include the four-
inch base for five miles of sheet asphalt pavement built
during 1895 to l899, in the city of Niagara Falls, N. Y.,
by Walter Jones, city engineer, in proportions of one
Portland cement, five sand and ten stone, at a total cost
per cubic yard, in 1897, °f $4.00. The items were :

i-io cubic yard (or 68^ of a 4-foot barrel) of high grade Port-
land cement, at $1.75 per barrel $i 20

5-10 cubic yard of graded pit-sand, fine to coarse, at $1.10

per cubic yard ^

i cubic yard of crushed and dust-screened limestone at $1.25

per cubic yard i 25

Mixing and placing and ramming " dry "-mixed concrete,

one cubic yard i oo

Total per cubic yard $4 oo

The results were good.

Portland Cement. — Of forty-two cities, one-third use
Portland cements in the proportions of one cement, three
sand and six to seven stone or gravel, at an average
cost, for twelve cities, of $5.30 per cubic yard.

Natural Cement. — Two-thirds of these forty-two
cities use natural cements in the proportion of one
cement, two sand and four to five stone or gravel, at an
average cost, for sixteen cities, of $3.85 per cubic yard,

Cost of Extra Work. — The cost of materials makes
up seven-eighths of the expense of concrete, so that
the extra precautions which have here been indicated
and which may increase the labor ten per cent, will
add little to the cost per cubic yard of the result.

CITY ROADS AND PAVEMENTS.

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BLOCK-STONE PAVEMENTS.

Block-stone pavements are forms of the most ancient
pavements, the details of which have been adapted to
the conditions of modern city traffic.

Examination of the conditions in the great cities
which do the best street-work, and which employ the
best skill to plan and to execute it, shows that block-
stone pavement of all kinds have long been regarded
as necessary evils which have only been tolerated
because they were improvements on the barbarous cob-
ble-stone pavements which formed the first stepping--
stones out of the mud, and because better substitutes
were lacking. There have been obvious advantages
which have off-set the evident disadvantages, thus
inducing a more general use of block-stone than is now
necessary.

Block-stone pavements are now only desirable for
steep grades, or for those streets of the largest cities
where the heaviest traffic exists. There is no such
traffic in any city of moderate size.

It has been considered until recent years that blocks
of the hardest trap rock, or basalt, or granite were best
adapted to endure the class of traffic which required
block-stone, and vast sums have been spent in prepar-
ing and laying blocks of granite from Massachusetts,

. 57

CITY ROADS AND PAVEMENTS.

CLERMONT AVENUE, BROOKLYN, N. Y.
Paved about 1880.

EIGHTH AVENUE, BROOKLYN, N. Y.
OLD COBBLE-STONE PAVEMENTS.

Jan. i, 1901, New York City (Manhattan) had 227 miles of cobble.
Brooklyn had 300 miles of cobble and defective blocks.

BLOCK-STONE PAVEMENTS.

Maine and Vermont, and of diabase trap rock from the
Palisades of the Hudson.

Paving blocks formed of these rocks and laid in the
usual manner with sand joints, wear in such a way that
their tops become rounded and polished, giving a poor
foothold for horses, and forming a surface which collects
and retains filth, and causes noise, and is injurious to
public health and comfort: the hardest and finest-
grained rocks giving the worst results, so that the
coarser grades of granite have nearly displaced trap
rock for paving blocks.

Granite pavement

Broadway, New York, has very heavy traffic and has
been repeatedly paved, from Fifty-eighth street to the
Battery, five miles, with various forms of granite and
of trap blocks ; portions of which have needed relaying
after three years' use, and all of which have been dirty
and noisy. These conditions are showrn to be unnec-
essary by the fact that during 1900, this block-stone
pavement was re-set and used as the foundation for
noiseless sheet-asphalt, which can be kept clean, and
which is guaranteed to be in perfect condition during
and at the end of ten years. This was done from
Fifty-eighth street to Fourteenth street, two and a
half miles, (and also on sixty other streets in New
York,) during 1900, and was extended to Canal street,

CITY ROADS AND PAVEMENTS.

Opera House.

BROADWAY, NEW YORK, 1900.
Looking up from the Casino at Thirty-ninth Street.

After paving with sheet-asphalt, in 1900 : Trinidad Lake wearing-surface ;
Bermudez Lake binder-coat,

BLOCK-STONE PAVEMENTS.

one and one-fourth miles, during 1901, and in 1906
wood blocks displaced block stone from the City Hall
to the foot of Broadway at the Battery. Many other
cities of the United States have, during the past ten
years, preferred to use sheet-asphalt or brick rather
than granite blocks, with the result that the total annual
expenditure of the cities of the United States for granite
block pavements has decreased one-half since 1890.

The ill results obtained from pavements of granite
and trap blocks are much less marked when the pave-
ments are formed of blocks of Medina, N. Y., sandstone
or Kettle River, Minnesota, sandstone. These sand-
stones wear flat, do not polish, and approach granite in
their resistance to crushing force, as indicated by the
following statements of average pounds of crushing
force endured per square inch : —

Maine granite, 15,000 to 22,000 pounds; Quincy
granite, 19,500 pounds; average of several of the New
England granites, 22,000 pounds; Palisades diabase
trap, 19,700 pounds; Medina, N. Y., sandstone, on bed,
17,500 pounds ; Berea, Ohio, sandstone, 10,250 pounds ;
Oxford, N. Y., blue stone (sandstone), 13,470 pounds;
Kettle River, Minnesota, sandstone (after seasoning),
on bed, 12,300 pounds.

Paving blocks of Medina sandstone are used to the
largest extent in the cities of Rochester and Buffalo,
N. Y., and Cleveland, Columbus and Toledo, Ohio, and
are quarried along both sides of the Erie canal in
various places from thirty to fifty miles west of Roch-
ester, N. Y. The methods are particularly good in
Rochester and in Cleveland, where the best pavements
are laid on concrete foundation. At Rochester, the
half-inch joints are filled with hot coarse sand and hot

CITY ROADS AND PAVEMENTS.

Setting Medina sand-stone blocks on six-inch concrete base covered with one and
one-half inches to two inches of sand-cushion.

Filling joints with coarse sand and hot paving cement.

BLOCK STONE PAVEMENT, ROCHESTER, N. Y., 1900.
62

BLOCK-STONE PAVEMENTS.

paving cement. The pavements are built by Edwin
A. Fisher, M. Am. Soc. C. E., as city engineer, and the
results are the best of which the material is capable, at
a cost, in May 1901 of $2.48 per square yard completed
including six-inch foundation of Portland cement con-
crete. At Cleveland, Ohio a similar pavement is built
with close joints.

Paving blocks of Kettle River sandstone are used in
Saint Paul and Minneapolis, Minn., and are quarried
at Sandstone, Minn., about one hundred miles north-
east of Minneapolis. The method of construction and
the results are similar to those at Rochester, N. Y., the
joints being half an inch wide and being filled with
equal parts of Portland cement and sancl. The cost at
St. Paul in 1900, including six-inch concrete base, was
$2.45 per square yard completed.

MILEAGE OF BLOCK STONE PAVEMENTS
(on basis of 30 feet width or 17,600 square yards per mile).

CITY.

State.

Year.

Granite.

Diabase
Trap.

Sandstone.

Albany

N Y

IQO2

28 miles

2 miles

Atlanta

Georgia

IQ02

52 miles

Boston

Mass

1902

114 miles

Buffalo

N. Y

iSqq

108 miles

Chicago.

111

1800

21 miles

Cincinnati

Ohio

1902

58 miles

Cleveland.

Ohio

1900

121 miles

Columbus.

Ohio

1900

2 miles

7 miles

f Brooklyn. .

N. Y. . .

1902

146 miles

i mile

1 Bronx

N. Y. . .

1902

44 miles

7 miles

NEW YORK -j Manhattan

N. Y. . .

1902

192 miles

87 miles

| Queens . . .

N. Y. . .

I9OI

29 miles

7 miles

[ Richmond.

N. Y. . .

I9OI

y2 mile

-TTT mile

Philadelphia

1902

340 miles

Richmond

1902

i mile*

Rochester
St. Louis
St. Paul

N. Y. . .
Mo

Minn.

igoi
1902
IQOI

70 miles

31 miles
3 miles

Toledo

Ohio

I9O2

6 miles

Troy

N Y

I9O2

26 miles

3 miles

Washington

D C

I OOO

28 miles

* Also 31 miles of "granite spalls

CONCRETE PAVEMENTS.

Pavements of Portland cement concrete, like that
used for sidewalks, have been built to some extent in
France and in several American cities; among them
Belfontaine, Ohio, where the main street was so paved
in 1892 and was still in use in 1904, grooves having
been cut in an attempt to prevent slipping.

In Toronto, Canada, concrete pavements were built
in 1899 and in 1903, consisting of the usual four-inch
concrete base (see page 42) upon which, before this
base had set, was spread the \vearing-surface of a finer
concrete composed of i part cement, i part sand and
3 parts finely crushed granite. This was made 2 %
inches thick, being worked into bond with the base-
course, and, while soft, its surface was divided by half-
inch grooves into five-inch by twelve-inch blocks to
afford foothold for horses. The omission of these
grooves would have left the surface slippery. Half-
inch expansion-joints, filled with paving-pitch, were
made along each curb and across the street at about
50 feet intervals. The cost in Toronto was $1.74 to
$1.92 per square yard complete without guarantee, and
in Philadelphia alleys the cost was $2.15, including
curbs and drains. Such a pavement should give good
results, under ordinary traffic, on moderate grades, if
well built.

During 1906-7-8, concrete pavements have been built in many cities ;
among them Chicago and Kewanee. Illinois; Grand Rapids, Calumet,
Hancock and Kalamazoo. Michigan; Richmond and Gary, Indiana; and
Washington, D. C., and Fon du Lac. Wisconsin/. In some case's it has
been subjected to heavy traffic which it has well endured when crushed
granite screenings, %. inch to dust, have been used in lieu of sand in
forming the mortar for the surface coat: This adds about 15 % to the cost
and increases the strength. The pavement is usually made 7 inches
thick, being 5^ inches base of i : 2 : 4 concrete, covered before setting
with 1 1^. inches top of i : i y2 mortar formed of Portland cement and
granite screenings: This is worked with steel trowel and cork float to
avoid a glassy surface, and has l/2 inch grooves, 4^ by 9 inches apart, to
give foot-hold, i inch asphalt mastic joints, 50 feet to 75 feet apart,
allow for exp3nsion. The cost, including 5-year guaranty, has been
$1.10, -$1.25 to $i.6o,-$i.S8 per square yard.

WOOD BLOCK PAVEMENTS.

es ^

§1
£ "r

O c

WOOD PAVEMENTS.

Wood-block pavements, as built since 1900, surpass
others in freedom from noise, and rank among the best
in qualities and in cost.

Of the many forms of wood pavements which have
been built, only those need be described in detail which
are still in actual construction : brief descriptions being
given of the cheaper forms, which are only regarded as
temporary expedients, and fuller details being shown
of those latest and most improved forms of wooden
block pavements which are now ranked with the best
class of modern work.

The corduroy roads of a century ago are now best
known in the tales of our grandfathers, although there
can yet be found, crossing swamps on the line of the
old military road which was built in 1812 across the
Adirondack wilderness, from the Mohawk valley at
Schenectady to Ogclensburg on the St. Lawrence, and
to Sackett's Harbor on Lake Ontario, sections of
corduroy road, which are still as sound as when laid,
having been preserved from decay by the water which
has usually covered them, although huge forest trees
have meantime grown up in the old and abandoned
roadway near at hand.

The plank roads of a half century ago are nearly
gone, with the toll-gates which were the objects of their
beginning and the cause of their ending; though it is of

ROUND CEDAR BLOCK.

curious interest that there are still, in 1904, two plank
roads leading from the westward into the city of
Albany, N. Y., having five toll-gates on ten miles of
road ; but these relics of old days are of only historic
interest, as are the majority of the thirty patented and
forgotten forms of wood pavements which had their
rise and fall thirty to forty or more years ago, beginning
in Boston, Philadelphia and New York about 1840 and
culminating from 1860 to 1870, in the "Nicholson
block," of which a description is now useless.

ROUND CEDAR BLOCK.

The well-known round white-cedar block pavement
came into general use in western cities about 1880, in
response to an urgent demand for something quick and
cheap which would last until the abutting lots could be
sold. This pavement was built in different ways in the
various cities, but it probably has its best form as still
built in Chicago in 1900. The prepared subgracle of
the street is covered with two inches of sand, in which
are embedded, across the street at six feet intervals,
one-inch by eight-inch pine boards laid flat, as supports
for the ends and centers of two-inch hemlock plank laid
lengthwise of the street and close together, forming a
regular crowned surface.

The cedar blocks are of sound live wood, free from
bark, not less than four, nor more than eight inches in
diameter and six inches long. These blocks, unsea-
soned and untreated, are set on end in close contact, and
the irregular interstices are rammed full of half-inch to
one and one-half inch gravel. The surface is then
flooded twice with coal-tar heated to 300° Fh., using two
gallons per square yard in all, followed while hot with

CITY ROADS AND PAVEMENTS.

a three-fourth-inch layer of clean gravel, not exceeding
half-inch, which has been screened from that used to
fill the spaces.

In 1900, this cost about seventy cents per square
yard in Chicago, where there was then about 880 miles
(on basis of thirty feet width) of streets thus paved.
This being probably somewhat more than the total
similar mileage in all of the other cities using this form
of pavement, the relative amounts being in about the
following order: viz., Detroit, Superior, Duluth, Mil-
waukee, Minneapolis and Toronto.

It usually needs renewal in six years and becomes
impassable in nine years, though the results are some-
times much better than this.*

Cypress blocks were similarly used in Omaha, Des
Moines and Kansas City, and failed in two to four
years.

BLOCKS ON SIX-INCH CONCRETE BASE.

Hexagonal blocks of mesquite, 5" deep and 4" to
8" diameter have been laid at San Antonia, Texas, at
cost of $2.80 per square yard, including the six-inch
base.

Tamarack-blocks, 3" by 5" by 6" have been laid in
Montreal and coated with hot coal-tar and gravel.

Redwood blocks, 4" by 6" by 6" seasoned, and boiled ,
in asphalt, have been laid in San Francisco and Oak-
land, California.

Yellow pine blocks, 4" by 6" by 6" to 10" creosoted
with twelve pounds per cubic foot, were laid in Galves-
ton, Texas, in 1895-8.

Creosoted or " treated " blocks on concrete base are
recommended for fifteen miles of streets by the board
of local improvement of Chicago during 1902.

* One of the few pieces of this pavement to be seen in the Eastern States is on
Main street in Fultonville, N. Y., in the Mohawk valley opposite Fonda. This was
built in the spring of 1891 and in 1904 was in fair condition and likely to continue so.

WOOD BLOCK PAVEMENTS.

CITY ROADS AND PAVEMENTS.

Washington cedar blocks, sterilized and creosoted
with three to four pounds of creosote per cubic foot,
were laid on about four miles of Indianapolis streets in
1896, and some are in good condition in 1901. Some
of the wooden pavements built in Indianapolis about
that time have swollen and heaved badly.

Oregon red cedar and southern yellow-pine heart-
wood blocks, 4" by 4" by g" creosoted with ten pounds
per cubic foot, were laid in 1899 in Indianapolis at a
cost of #2.10 to $2.50 per square yard, including base
and five years guarantee : the joints being filled with
paving cement of nine parts coal-tar to one part asphalt,
and the surface being covered with half-inch screenings
of crushed granite. This is a much more costly pave-
ment than the others which have been described, and
is of a high class, as are the later improved kinds
described on page 74.

In Paris, pine blocks of several forms, creosoted with
eight to ten pounds of creosote oil per cubic foot, form
the greater part of the ninety miles (thirty feet width)
of wood-paved streets. Wood is preferred as being less
slippery and less noisy than compressed rock-asphalt,
and that it is satisfactory in its other qualities is evi-
denced by the fact that the amount of wood pavement
in Paris is increased every year. Including the six-
inch concrete base in both cases, the cost complete is
about the same as for rock-asphalt, viz., $3.10 per
square yard.

AUSTRALIAN HARD-WOOD PAVEMENTS.

These are the most costly of any of the various
wooden-block pavements and, therefore, have not been
laid to any extent in the cities of the United States.

They have, however, been largely used, and with good
effect, in London, which has wood pavements of many
kinds to the extent of about 240 miles, computed on a
basis of thirty feet width.

The city of Sidney, New South Wales, has many
miles of wood-paved streets, upon which Australian
hard woods have been used with most remarkable
results, which would be incredible if not substantiated
by the statements of W. A. Smith, M. Inst. C. E., and
also by the report of R. W. Richard, Asso. M. Inst.
C. E., the city surveyor of Sidney, and engineer in
charge of Sidney pavements. Queen street, which has
an estimated daily traffic of 25,000 tons, was thus paved,
and the blocks after eight years use, showed a greatest
observable wear of one-sixteenth of an inch and were
otherwise in almost as good a state in 1893 as when
laid. The original cost was $3.05 per square yard,
exclusive of foundations, with an annual cost of two
cents per square yard for maintenance and for daily
sanding.

The details of their construction in Sidney are as
follows :

CITY ROADS AND PAVEMENTS.

The foundation, or base, was a layer of one-to-seven
concrete, formed with a floated smooth surface, having
a convexity from one in forty to one in eighty, and
allowed to set for seven days before use.

This concrete base \vas six inches thick on solid
ground and nine inches thick on uncertain ground.

The pavement which gave the best result was formed
with seasoned heart-wood blocks of tallow-wood, black-
butt, and blue gum, red gum, jarrah or karri, each kind
being laid separately. Each block was formed by cut-
ting a three-inch by nine-inch plank into pieces six
inches long, and these blocks were then painted with, or
dipped in, hot coal-tar and hot wood-preserving oil, and
stacked for four hours before being set in the work.
The blocks were set on end with the fibre vertical,
forming three-inch rows across the street from curb to
curb, each block breaking joints two inches with blocks
in the next row.

To provide for the expansion of the blocks when wet,
expansion-joints were formed along each side of the
pavement; these joints being two inches wide between
the curb and the gutter-course, and an additional one-
inch joint between the gutter-courses, which were
forme<J of blocks set in rows running lengthwise of the
street. Curbs, eighteen inches deep, were needed to
resist the thrust which moved twelve-inch curbs. Bet'
ter results were reached when these expansion joints
were filled with mastic than when filled with sand or
with clay puddle. These widths of joint were used on
pavements sixty-four feet wide and gave good results.

The best results were obtained when the blocks
were forced close together on grades up to one in
twenty and with one-quarter-inch joints on steeper

AMERICAN HARD-WOOD PAVEMENTS.

1 3

o -s

K c

, S

E- 7

CO ^

^ -i

C T

O 'C

CITY ROADS AND PAVEMENTS.

grades up to one in thirteen, or eight per cent. After
completing sixty lineal feet of roadway, the surface of
the pavement was swept with hot coal-tar and sprinkled
with hot sand, and again swept with hot tar until the
spaces were thoroughly flushed with the plastic paste.

As to the durability of these hard-wood blocks as
compared with cubical blocks of blue-stone, Mr. Richard
states that the blue-stone blocks have shown a wear of
one inch per year, while the hard-wood blocks, laid as
described and subjected to similar traffic, have shown
a wear of one-fiftieth (TL) inch per year.

Where the joints have been filled with hydraulic
cement, the results were not as satisfactory as where
blocks were laid with close joints, but with the con-
struction described, these wood-block pavements are
free from the various faults of our cedar blocks and are
expected to have a minimum life of sixteen years, equal-
ing asphalt.

In Melbourne, similar pavement is estimated to last
fourteen years. Either of these improved methods or
the more crude ones generally used in this country are
costly. The final expense of our cheap construction
being twice as great as for asphalt or for granite blocks,
and probably much greater than if white oak or some
similar hard wood were used.

AMERICAN WOOD PAVEMENTS OF THE LATEST TYPE.

The valuable qualities of the highest grade of treated
wood-block pavements have been generally recognized,
especially their freedom from noise; but their extensive
use in the cities of the United States has been deferred
by distrust based upon former failures and by the
excessive cost. The cities seem to have awaited the de-

AMERICAN WOOD PAVEMENT.

velopment of some process of treatment of native woods
which should be less costly than the Australian hard-
woods just described, and more satisfactory in various
ways than the former well-known American methods.

The creosote as ordinarily used is an effective pre-
servative in itself, but it tends to form an emulsion with
water, and also to evaporate half to three-fourths on
exposure to the sun and the weather.

To avoid these defects has been the object of two
recent modifications of the treatment : the one called
" kreodone-creosote," and the other " creo-resinate."

CITY ROADS AND PAVEMENTS.

MERIDIAN STREET, INDIANAPOLIS, 1902.
Kreodone-Creosote Wood-block Pavement in progress in March, 1902.

KREODONE-CREOSOTE PROCESS.

This consists in impregnating the seasoned selected
blocks under pressure with ten pounds per cubic foot
of an oil derived from creosote oil, possessing the origi-
nal preservative properties with a longer endurance,
and also having the effect of forming a varnish-like film
or coating on the outer surface of the wood, protecting
it from the elements.

The seasoned blocks are sterilized by subjecting
them to dry heat of 240° Fh., for eight hours. The
kreodone-oil is then forced into the fibres of the wood,
under a pressure of seventy pounds per square inch,
maintained for two to three hours, or until twelve pounds
have been absorbed by each cubic foot of the wood.

In some cases the blocks are laid with the courses
running diagonally across the street. The cost in
Indianapolis for blocks four inches deep, has been $2.50
to $2.70 per square yard of completed pavement, includ-
ing concrete base, and also including nine years' guar-
antee and maintenance.

The cost of the Chicago pavement on Michigan
avenue, in front of the Auditorium hotel, for blocks
five inches deep, exclusive of the concrete base, and
including surety company guarantee for five years, was
$1.90 per square yard.

This Chicago pavement and that on North Dela-
ware street in Indianapolis, were both laid in 1901,
and will furnish conspicuous examples by which may
be observed the peculiar qualities of pavements treated
with kreodone-oil.

CREO-RESINATE PROCESS.

A pavement of pine blocks treated by this process
became known during 1900 and 1901 by being laid on
conspicuous streets in Boston and Springfield, Mass.,
and in New Rochelle, N. Y., and in Baltimore, Md..
The results have been such that each succeeding year
has added largely to its extent and to the number of
cities using it. The streets and bridges selected to be
paved with it being usually those having the densest
and heaviest traffic where a noiseless pavement was
desired, as in the case of lower Broadway in New York

TREMONT STREET, BOSTON, 1900.
Creo-Resinate Wood-blocks, laid in 1900.

CREO-RESINATE PROCESS.

City, which is thus paved from City Hall Park to the
Battery. Many quiet residence streets in New York
and Brooklyn and in U. S. Navy Yards and elsewhere
have been so paved.

The street superintendents of the cities where it has
been used concur in saying that it proves most satis-
factory, being noiseless, free from dust, not slippery
on grades when used with the grooved joint shown on
page 29, can be taken up and relaid readily, has as yet
nowhere required repairs, and is so durable that the
heavy traffic of Tremont street, Boston, has worn less
than one-eighth inch in three and one-half years.

The special features of the creo-resinate process are
the preliminary treatment in dry heat to kill the germs
of decay, and the mixing with the creosote of fifty per
cent of melted rosin which is forced into the fibres
with the creosote, where it solidifies and seals the pores
of the wood and prevents the evaporation of the creo-
sote or its displacement by water, which can find no
entrance, so that the pavement does not swell and
heave when wet.

The blocks are of Georgia long-leaf yellow-pine heart-
wood, 4" wide by 8" long by 3" or 3^" or 4" deep,
and are treated in an air-tight cylinder by dry heat for
five hours, during which time the temperature and
pressure are gradually raised to 285° Fh., and to
ninety pounds per square inch, when both are gradually
lowered and a vacuum is produced, followed by hot
creo-resinate mixture, afterwards forced in by hydraulic
pressure of 200 pounds per square inch, which is main-
tained until twenty-one to twenty-two pounds of the
mixture have been absorbed by each cubic foot of the
wood.

CITY ROADS AND PAVEMENTS.

This is followed, in another cylinder, by hot milk-
of-lime under the same pressure, in order to fix and set
the creosote, so that the blocks, when ready for use,
present a peculiarly solid appearance.

Creo-resinate blocks are peculiarly good for bridge
floors because of their durability, smoothness and light-
ness, and may be seen on the great Williamsburg
suspension bridge between New York and Brooklyn;
on the Harvard bridge, Boston ; on the Jackson street
bridge, Newark, N. J.; on the Buffalo Road viaduct
at Erie, Pa., and others.

In all cases the blocks are laid with the grain ver-
tical, and are bedded in a layer of Portland cement
mortar (or on a one-inch cushion of screened sand)
covering the usual six-inch concrete base. The blocks
are driven tightly together at every sixth row and are
rolled with a five-ton steam-roller until a firm, uniform
and unyielding surface is made.

The whole is then flushed, and the joints filled, with
Portland cement grout, or with creo-resinate mixture,
or best, with asphaltic filler; each having given good
results; the whole being then covered temporarily with
X-inch of clean screened sand.

COST.

The cost of this pavement, complete, including a
surety company ten-year guarantee, for blocks four
inches deep on concrete six inches deep, varies with
the local conditions from $3.10 to $3.50 per square
yard.

IRON-SLAG BLOCK PAVEMENTS.

Since about 1888, blast-furnace slag has been utilized
to a small extent in the Newcastle district of England,
and also in Europe, to make paving-blocks by running
molten slag into cast-iron moulds and allowing the
blocks to anneal for eight hours by their internal heat*
thus forming tough and hard blocks heavier than
granite; each being 8 inches long, 4 inches deep and
3^ inches wide with half-inch chamferred top edges;
these are set on the usual sand cushion on a concrete
base, preferrably with asphaltic joints to reduce noise.
The blocks show a whitish, stonelike surface and a
bluish, porcelainlike interior when chipped, and have
been imported from England in limited amounts for
use between and beside street-railway tracks in the
cities of New York, Baltimore, Philadelphia and Rich-
mond in the U. S. and in Quebec, Toronto and Mon-
treal in Canada. American slags which have been
tried do not become so hard and tough by annealing,
being too silicious and too low in alumina.

The cost per thousand has been $12 in England,
$34 in Canada, and $50 to $55 in the United States
where their further use in the Borough of Brooklyn
was considered during 1908. It does not appear that
their merits equal the excessive cost of importation at
such rates, although they have given good results in
some cases.

VITRIFIED BRICK PAVEMENTS.

THEIR USE IN THE UNITED STATES.

During the past seventeen years there has been a
steadily increasing use of vitrified brick for the pave-
ments of the streets of cities and towns in the United
States, especially of those of moderate size — that is, of
100,000 inhabitants and less: the larger places wel-
coming brick as a competitor with sheet asphalt, and
as affording another means of escape from the intoler-
able noise and dirt resulting from block-stone pave-
ments and from the temporary and unsanitary features
of cedar blocks, while the smaller western towns, with
characteristic enterprise, have built miles of brick pave-
ments to displace the natural mud. The total length
of brick-paved streets in the United States in February,
1902, was estimated by Wm. S. Crandall, then editor
of The Municipal Journal, at about 1300 miles, and
this has since been largely increased.

The following table is reprinted from the first edition
of " City Roads and Pavements," and shows the modes,
costs and results in sixty-five cities in 1894:

VITRIFIED BRICK PAVEMENTS.

Brick at entrance to Union Station, laid in 1893.
(Stone-block pavement in foreground ).

Alley paved with brick in 1894.
BRICK PAVEMENTS, ST. LOUIS, 1901.

SUMMARY OF REPORTS OF MODES OF CONSTRUCTION, COST AND
RESULTS OF VITRIFIED BRICK PAVEMENTS.

CITY AND STATE.

Miles
n use
June,
1894.

Cost per Square Yard of "Best
Work" on the Foundation
here indicated.

Filling of ;
Joints. :

Reported
Results.

Six
inches
Concrete.

Flat
Brick or
Gravel.

Broken
Stone or
Gravel.

Atlanta. Ga
Atchison, Kan
Alton, 111
Alleghany, Pa
Bellaire Ohio

1.1
2.75
1
2

$2.19

Paving tar.
Sand.
Sand.
Paving tar.

Satisfactory.
Excellent.

$1.75
2.16

1.60

Fair.

$0.61

Binghamton, N. Y.
Bloomington, 111...
Buffalo N Y

6.25
6
3 33

2.40

Cement grout.
Sand.
Cement grout.
Sand.
Sand.
Sand.
Paving tar.
Paving tar.
Sand.
Paving tar.
Sand.
Sand.
Sand.
Cement grout.
Sand.
Paving tar.
Paving tar.
Sand.
Cement grout.
Sand.
Paving tar.
Cement grout.
Sand.
Sand.
Cement grout.
Paving tar.
Sand.

Sand.'
Sand.
Sand.

Fair.
Good.
Fair.
Gratifying.
Fair.

2.00

2 75

Burlington. la
Cedar Rapids. la. . .
Charleston, W. Va.

7.50
2

1.60
1.35

1.15

1
15
10
30
2
5
6
0.4
15
9 6

2.30
2.50

Satisfactory.
Fair.
Good.
Good.
Excellent.
Good.
Good.
Good.
Good.
Fair.
Good.
Satisfactory.
Good.

Cincinnati, Ohio...

i.45

Columbus, Ohio . . .
Connellsville. Pa. . .
Council Bluffs, la..
Davenport, la
Dayton Ohio

2.00

2.49

1.50
1 HO

2.30

Decatur, 111
Detroit Mich

1 75

2 50

DesMoines, la
Dubuque, la
Dunkirk, N. Y

10
1.5
2.5
4 5

1.70
1.69
2.10
1 70

1.87

Findlay, Ohio
Fort Wayne. Ind..
Galesburg 111

4
2
12
1.5

1.75

Satisfactory.
Good.
Good.
Perf ly. satisfy.
Good.
Good.
Good.
Fair.
Good.
Good.
Good.
Good.
Good.
Good.
Excellent.
Good.
Good.
Entirely satis.
Good. .
Moder'tely fair
Good.
Fair.
Good.

Gocd.
Good.
Good.
Satisfactory.
Indifferent.
Good.
Good.
Good.
Good.

Good.'
Good.
Good.
Good.

Satisfactoiy.

1.63

"'i!8o' "

2.05

Hannibal, Mo

0 12

4 00

Indianapolis Ind .

8.7

2 35

Jacksonville, 111 ...
Kansas City, Mo.:.
Kenosha, \Vis
Keokuk la

9
10.25
1
1.25
2.50
0.10
6
15
10
10
9
2.25
1.50
10.25
2.25

20
1
6
3.14
1.82

0.34

1.40

'"iiss'V

2.00

1 55

Lafayette, Ind
Lancaster, Pa
Lexington, Ky
Lincoln, Neb
Lockport, N. Y
Louisville, Kv
Massillon, Ohio
Memphis, Tenn
Olean, N. Y
Omaha, Neb
Ottawa, 111
Peoria 111

1.80

1.80
2.25

Paving tar.
Cement grout.
Cement grout.

1 75

2.09
1.50

1.40

Sand.
Paving tar.
Cement grout.
Sand.
Sand.
Sand.

2.65
2.00

1.87

1 40

1.75
2.05
3.00

Philadelphia, Pa...
Providence. R. I ...
guincy, 111
ochester, N. Y...
Rockford, 111
Rock Island, 111....
St Paul, Minn

'"i'.so"

Paving tar.
Sand.
Paving tar.
Sand.
Sand.
Sand.
Cement grout.
Sand.
Sand.
Cement or tar.
Cement grout.
Sand.
Cement grout.
Cement grout.
Sand.
Paving tar.
Cement grout.

2.30

1.75
1.62
2.40

1.37
1.33

Scranton Pa

0.10
5.38

2.33

Springfield 111 ...

1.35

1.00

Steubenville, Ohio.
Syracuse, N. Y —
Terre Haute, Ind. .
Toledo, Ohio
Troy, N. Y
Washington, D. C-.
Watertown, N. Y..
Wheeling, W. Va..
Wilmington, Del...

10
5
1
16.33
1
0.25
0.12
2
3

"'2!l5'"

2.25
1.05

2.50
2.05
2.46

1.35
2.15

Average of prices.

$2.19

$1.75

$1.52

REACTION AGAINST USE OE BRICKS.
EXTENT OF ITS USE.

Two to three hundred such cities and towns, as well
as all of the larger cities, especially Philadelphia, have
laid more or less vitrified brick pavement, and its use
is constantly extending, as is shown by the accompany-
ing table on page 130, compiled by Willis Fletcher
Brown, city engineer of Toledo, Ohio, showing the
miles of streets paved with brick and with sheet asphalt
in thirty cities.

This table also shows the relative estimation in
which brick is held as compared with sheet asphalt in
cities where both have been used for a period long
enough for opinion to be formed.

REACTION AGAINST USE OF BRICKS.

There has undoubtedly been a reaction in the popu-
lar desire for brick pavements in some of these cities,
where people have learned to know what good pave-
ments are and where brick pavement has been brought
into close comparison with sheet asphalt, and with the
best grades of creosoted wood-block pavements in the
western cities, and more recently by comparison with
bituminous macadam or bitulithic pavement, in a few
of the cities of the east.

The excessive and peculiar roaring noise produced
by the passage of light wagons over some brick pave-
ments is objectionable on residence streets, and on
some streets having heavy traffic there have been
poor results as to durability. Much discredit has also
been thrown upon the use of vitrified brick by the care-
less and ill-judged manner in which many manufac-
turers have sent out irregularly and imperfectly burned
brick. These have been laid by incompetent contrac-

CITY ROADS AND PAVEMENTS.

tors, under inexperienced city officials, and have thus
caused the needless failure of many pavements, thus
stopping further extensions and preventing other cities
from using brick at all, to the great gain of the sheet-
asphalt companies, and with the effect of encouraging
the introduction of bituminous macadam, creo-resinate
wood blocks and other high-grade pavements which
are free from these defects and which have not yet had
time to develop other defects which may be peculiar to
themselves.

REGION OF PRODUCTION.

The production of vitrified paving brick in 1894
was in a measure restricted within two regions of Penn-
sylvania and Ohio on the southwest and Indiana and
Illinois on the west, which produced the special quality
of material for forming paving bricks, which differ
entirely from ordinary building bricks in both their
material and mode of manufacture and in their qualities ;
the name being a misleading one, as they are not brick
but tile, and are not actually vitrified, but are fused.

There are now a number of places outside these
limits where paving bricks are produced in large quan-
tities, one of the large plants being on the Hudson
river at Catskill, from which have been furnished bricks
for pavements in 112 cities and towns, nine-tenths of
which are in seven of the eastern states, and the rest
are in six of the southern states. The material of
these bricks is low-grade iron ore, shale and clay, which
are ground to a powder and mixed in proper propor-
tions and formed into repressed bevelled-edge vitrified
paving bricks and blocks, which compare well with
others, and which have been used for most of the brick
pavement in Albany, N. Y., with good results.

CHARACTERISTICS.

Other well-known kinds of high-grade paving mate-
rials are the Mack bricks and blocks, made at very
large works, located at New Cumberland, W. Va.,
fifty-six miles west of Pittsburg, Pa. These have been
used for pavements in 100 cities and towns, two-thirds
of which are in five of the eastern states, the rest being
in three of the middle western states and four of the
southern states.

The materials are silica, alumina and iron, forming
fire-clay, which is ground to powder and mixed with
water in proper proportions and moulded into bevelled-
edge vitrified paving bricks and blocks.

Streets of Philadelphia, equal to over sixty miles
length of thirty feet width, have been paved with these
blocks, and it is stated by Wm. H. Brooks, chief of
bureau of highways of Philadelphia, that some streets
thus paved for over ten years have required no repairs
and are now in good condition.

CHARACTERISTICS.

The material for moulding any paving brick must be
of a peculiar character which will not melt and flow
when exposed to an intense heat for a number of days,
but will gradually fuse and form vitreous combinations
throughout, while still retaining its form.

The resulting brick must be a uniform block of
dense texture, in which the original stratification and
granulation of the clay has been wholly lost by fusion
which has stopped just short of melting the clay and
forming glass.

The clay while fusing must shrink equally through-
out, thus causing the brick to be without any lamina-
tions or any exterior vitrified crust differing from the

CITY ROADS AND PAVEMENTS.

ABRASION AND IMPACT TEST.

interior. Such a brick will be incapable of absorbing
any considerable amount of water, and will hence be
unaffected by frost, and if formed of the best material
properly treated will be tough, to withstand the blows
of horses' toe-calks; hard to resist the abrasion of
wheels, and strong to carry heavy loads: these being
in the order of effectiveness of the destructive forces to
be met.

There is now little difficulty, with rigid inspection,
of getting brick which will uniformly possess these
qualities.

QUALITIES OF PAVING BRICK.

If the brick are uniform in character and are per-
fectly formed of proper material which is thoroughly
fuzed, they will be harder than glass and nearly as hard
as quartz (being 6.5 on Mohs' scale), and will be tough
enough to endure traffic. These qualities will be best
determined by the following described test:

ABRASION AND IMPACT TEST.

The standard test revised and adopted by the Na-
tional Brick Manufacturers Association in 1900, pro-
vides for the use of a machine having a rattling
chamber twenty-eight inches in diameter and twenty
inches in length, formed of two steel heads and four-
teen steel staves set one-fourth inch apart to allow the
escape of the chips and dust. This machine must be
set to run uniformly at about thirty revolutions per
minute for about sixty minutes, or for 1,800 revolutions
by actual count of a cyclometer. Each separate charge
of bricks to be tested must consist of bricks of one

CITY ROADS AND PAVEMENTS.

kind, which must be perfectly clean and dry, and free
from moisture : twelve paving bricks or nine paving
blocks (so called because larger), are accurately weighed
and constitute a charge, together with 300 pounds of
cast iron in the form of blocks with rounded edges and
corners : one-fourth in weight to be two and one-half
inches square on end and four and one-half inches
long, and three-fourths to be one and one-half-inch
cubes.

After 1800 revolutions, made as stated, the loss is
determined by again weighing the brick: the limit of
loss which is allowed varies in different specifications :
the St. Louis specifications reject bricks when the
tests show a loss of over thirty per cent of the original
weight : Columbus, Ohio, puts the limit at twenty-
seven and one-half per cent : many lots of bricks tested
will lose less than twenty per cent.

Such brick must be practically without pores, for
a brick which can absorb water equal to more than two
per cent of its dry weight, will probably fail to endure
the rattler test.

The absorption test is, therefore, not a useful one,
and may mislead, and may safely be omitted.

The tests by abrasion, and for absorption, and for
crushing strength,- are the most important of the numer-
ous tests which are sometimes specified, and of the total
value of all the tests, the abrasion test is variously con-
sidered as varying from thirty per cent to seventy-five
per cent of the whole.

EXAMINATION OF BRICKS IN USE.

The best and most useful test can, however, be made
by visiting places where brick pavements have been in

EXAMINATION OF BRICKS IN USE.

use for several years, and by examining the actual
results of traffic upon well-known and standard makes
of brick.

For instance, Columbus, Ohio, has some eighty miles
of brick pavement, varying in age from one to twelve
years, in which twenty-six kinds of paving bricks and
blocks have been used, with various kinds of fillers in
the joints. Dayton, Ohio, has twelve miles of brick
pavement, in which fourteen kinds of bricks and blocks
have been used.

Des Moines, Iowa, and Terre Haute, Indiana, have
also large mileage, composed of great varieties of mate-
rials, as have also Cleveland and Toledo, Ohio, Louis-
ville, Ky., and Detroit, Michigan.

A few days spent in such examination of pavements
in actual use will make experiments unnecessary, and
will enable the engineer who is planning new work to
avoid poor bricks and to specify those kinds which can
be depended upon to give good results.

This method of natural selection is gradually forcing
the poor grades of brick out of the market.

CITY ROADS AND PAVEMENTS.

Mixing and placing concrete base.

Placing brick on sand cushion.
BRICK PAVEMENT, PROSPECT STREET, CAMBRIDGE, MASS., 18

BUILDING BRICK PAVEMENT.

Rolling -with two and one-half ton roller.

Spreading Portland cement grout filler.
BRICK PAVEMENT, PROSPECT STREET, CAMBRIDGE, MASS.

CITY ROADS AND PAVEMENTS.
VARIOUS STYLES OF CONSTRUCTION.

The table on page 84 is reproduced from the first
edition as showing the actual practice in 1894 in the
sixty-two cities there named, of which thirty-four then
used one course of brick set on edge on a six-inch
concrete base with a sand-cushion of one inch.

Vitrified BncK"

Sand
Concrete

Briclf pavement

The table on page 100 shows a more general use of a
concrete base in 1900 and 1901, and this is to be
expected as showing a higher standard of work obtained
at less cost. Broken stone forms a good base, especi-
ally where it is covered with a layer of sand, with a
course of second quality of brick, laid flat, as founda-
tion for the surface-course of brick set on edge.

Two courses of brick on sand have been used for
seventeen miles of pavement in Topeka, Kansas, some
of which has been in use for twelve years, and all of
which is in fine condition in 1902. It is there pre-
ferred as being less noisy than when laid upon a con-
crete base, and being made from local brick has cost
$1.25, or less, per square yard.

A concrete base, for which details are given on page
42, is, however, usually well worth the extra cost, and
should be used in preference to any cheaper substitute ;
especially for a city which has been educated to a cor-
rect idea of what constitutes a good pavement.

SAND CUSHION.

MODE OF CONSTRUCTION.

The earth roadbed being sub-drained and rolled
hard, as described for other pavements, should be
formed with a regular crown of about one one-hundreth
the width between curbs: the best amount of crown
is an important matter discussed on page 30, and the
following table is given to show the practice in 1900
in twenty-seven cities having experience with brick
pavements:
ACTUAL "CROWN" OF BRICK PAVEMENTS AS BUILT IN 1900.

CITY.

STATE.

|||

CITY.

STATE.

SLf |

CITY.

STATE.

!li

4J •* C

Albany
Atlanta

N. Y..
Ga

5
5

Fort Wayne. .
Grand Rapids

Mich ..
Mich ..

4
6

New Orleans
Peoria

La....

111......

5
6

Binghamton. . .
Buffalo
Columbus
Dayton .

N. Y..
N. Y . .
Ohio...
Ohio...

41A

Harrisburg. . .
Houston
Jackson
Joliet

Penn . .
Texas. .
Mich..
Ill

5
6

Sandusky ....
Scranton
Springfield . . .
St. Paul

Ohio...
Penn . .
Mass . .
Minn . .

Detroit

Mich

Mansfield .

Ohio..

Terre Haute.

Ind....

Elmira

N. Y..
Penn

6 4

Meridan

Conn . .
Wis

Toronto
Troy

Ont ...
N. Y..

7
4

BASE FOR BRICK PAVEMENT.

This may be formed in either of the several ways
mentioned on page 94, but should generally be four
or six inches of concrete, as detailed on pages 42 to 56.

SAND CUSHION.

When ready to set the brick, the sand cushion is
formed by spreading screened moist sand over the con-
crete or other base : this is spread uniformly to the
required depth of one and one-half to two and one-half
inches, and smoothed and brought to the proper crown
by wooden templates, traveling on wheels or shoes and
resting on the top of the curbs on either side. Upon
the true surface thus formed upon the sand, the brick
are set on edge, the workmen standing only upon the

CITY ROADS AND PA.VEMENTS.

brick already laid, and placing the bricks in front of
them in regular lines across the street; the brick in
each course breaking joints with those in the next
courses. The bricks are then rammed with a seventy-
five pound rammer and rolled with a two and one-half-
ton or a five-ton steam roller and settled firmly into the
sand-bed. If the surface is then sprinkled and examined,
soft brick can be detected and picked-out as being those
which remain wet after the hard bricks have dried.

JOINT FILLERS.

No filler has yet been found that is perfect, and
there are wide differences of opinion as to the best.

Sand filler is cheap and allows the brick to be readily
taken up and relaid, but it also allows the edges and
corners of the bricks to chip and become rounded, and
permits the bricks to settle at soft spots of subgrade.

Portland Cement Grout of equal parts by bulk, of
loose cement and fine sand, if properly made and
applied, is better, and there are patented mixtures
which are combinations of iron-slag and cement ground
together, and which are equally good or better. Grout
is irregular and worthless, unless the sand used is so
fine as to remain in suspension, and such sand is not
easy to obtain : grout should be poured into place, but
is sometimes flushed broadly over the surface and swept
into the joints. Grout makes it difficult to take up and
relay the brick, but it can, if properly made and applied,
perfectly protect their edges and corners and thus pre-
serve a smooth surface, which is most desirable.

For some reason which is not clear, the pavements
with cement grout joints seem to be the most noisy.

Paving Cement makes an elastic joint which in some
cases is best, although it costs more than grout. The

Cost of joint fillers for brick per square yard of pavement : Sand, 2 to 4 cents ;
Portland cement grout, 8 to 12 cents ; paving cement, 10 to 12 cents ; asphalt filler,
14 to 16 cents.

JOINT FILLERS.

usual composition consists of 100 parts by weight of
No. 4 coal-tar, three parts residuum oil and twenty parts
refined asphalt, kept and used at a temperature of 300°
Fh., meantime carefully avoiding over-heating it. This
hot mixture should be poured into the joints from a
spout, or it may be poured upon the surface and swept
in with steel wire brooms: a thin coating of sand
should be at once spread over the pavement, and this
will mix with the surplus pitch while still hot so that
traffic will soon grind the whole from the surface and
leave the bricks clean.*

Expansion. — The expansion of brick pavements
during and after periods of extreme heat has been a
frequent source of trouble, and many pavements have
been thus heaved and broken ; in some cases by a quiet
raising of the brick pavement until the arch thus formed
was broken by its own weight or by traffic, as occurred
at Niagara Falls in July, 1897, and at Glens Falls in
August, 1901: in other cases by sudden ruptures or
explosions, as at Kansas City in July, 1901, where this
occurred on seven streets and brick were thrown up a
foot or more. In nearly every case this peculiar result
has occurred where the brick have been laid with cement
joints, and where the cross-expansion has been pre-
vented by rigid curbs ; or at the apex of grades from
both ways, or at the top of a steep incline where the
resulants of longitudinal expansion have been concen-
trated at one place.

Expansion-joints of one inch of coal-tar, or mastic, or
bitumen or sand have been formed along the curbs on
both sides of the street and across the pavements from

* In 1905, the best elastic filler for brick pavement was made from refined asphal-
tum by the American Asphaltum and Rubber Co. of Chicago. This stays in, and
fills, the joints in hot weather (not flowing below 215° Fh.) and yet is soft at ordinary
temperatures but is not brittle in cold weather, nor affected by water. Its use
strengthens the pavement and lessens the noise which has been the chief objection
to brick.

CITY ROADS AND PAVEMENTS.

curb to curb at intervals of fifty feet: one city in cen-
tral New York took special precautions of this kind
and yet has had more or less trouble every year.* Other
cities have taken no precautions and have no trouble.
It remains to find a preventive.

BRICK PAVEMENT FOR STEEP GRADES.

Brick pavements are often used successfully on
grades which are considered to be too steep for smooth
asphalt, which may afford no foothold, or for macadam,
which may be gullied by heavy rainfalls. It is often
difficult to decide what pavement to use in such cases,
and equally difficult to select from the various forms
of vitrified bricks and the different ways of laying them,
in order to secure the best results on steep slopes.

The following table is given of the steepest grades
of brick pavements, in actual use in 1900, in the cities
named : the fact that such steep grades are in use,
may not be taken as a reason for imitation, but may
furnish conclusive reasons for avoidance.

MAXIMUM GRADES OF BRICK PAVEMENTS — 1900.

Grade

CITY.

State.

in feet

CITY.

State.

in feet

feet.

Albany

N.Y...

9-3

Nashville

Term . .

Baltimore

I r

Parkersburg . .

W. Va

Columbus

Ohio

Peoria ....

111..

8.4

Des Moines . . .

Iowa . .

1 1

Philadelphia. .

Penn . .

Erie

Penn

St Joseph

Joliet .

111

Toledo . .

Ohio

c.6

Mansfield

Ohio

Troy

N Y

Milwaukee ....

Wis . . .

Wheeling ....

W. Va.

* Along the center-line, and on cross-lines 50 feet apart, four joints were filled
with "asphalt mixture" (page no) instead of i to i Portland cement grout. In every
case, the three lines of adjoining brick thus laid settled during the first summer,
displacing the ^-inch sand cushion until the bricks rested on the concrete base.
This action formed bad depressions three courses wide, and the experiment was a
costly failure ruining the pavement, though it was still in use eight years later.

BRICK PAVEMENT FOR STEEP GRADES.

Cost. — The average cost of construction of brick
pavement on concrete complete in 1894, n°t including
curbing and extras, as shown by the table on page 84,
was $2.21 per square yard, varying from $1.56 at Alle-
ghany, Pa., to $3.00 at Providence, R. I.

In 1900, the cost is materially less, and the prices of
several are given as a basis, being obtained from the
" Engineering News " and the " Engineering Record,''
and from direct advices.

On April 10, 1900, at Chillicothe, Ohio, offers were
made by six bidders for pavement to be formed of either
of seven different kinds of first-class paving bricks, using
either of four different kinds of filler in the joints and
naming a price for each ; six inches of concrete forming
the foundation in each case. For the concrete base the
prices ranged from twenty-eight to thirty-four cents,
with an average of thirty-one cents per square yard.

For the bricks laid in place, the prices ranged from
seventy-seven to eighty-eight cents with an average of
eighty-four cents per square yard.

For the fillers, the prices per square yard ranged
from an average of nine cents for cement to an average
of sixteen cents for " No. 6 filler;" fifteen cents was bid
and accepted for " Murphy grout," a patented mixture
of powdered iron-slag and cement, which was used.

For the complete pavement (not including excava-
tion or curbs) the prices ranged from $1.24 to $1.38,
with an average of $1.33 per square yard.

On May 18, 1900, at Kewanee, Illinois, four bids were
made for vitrified brick pavement on six inches of con-
crete for which the price for base, pavement and filler
complete in place, ranged from $1.42 to $1.47, with an
average of $1.45 per square yard.

CITY ROADS AND PAVEMENTS.

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GUARANTEE.

These and other prices are given in the table on
page 100, in each case giving not only the minimum
price, at which the work was done in each case, but
also the highest bid and the mean of all the bids, for
use in preparing estimates of cost for similar works.

GUARANTEE.

Some cities now require that the price for a brick
pavement shall include a guarantee that it will be kept
in good condition for a term of years and delivered in
good condition at the expiration of this time. This
term varies widely as indicated by the records of fifty-
five cities of the United States which had, on January
ist, 1899, 571 miles of brick pavements: of these,
three require guarantee for one year; two for three
years ; thirty-two for five years ; one for six years ; one
for seven years, and ten for ten years ; while eleven
require no guarantee, some buying the brick and laying
them by hired labor. The general tendency seems to
be toward a five-year guarantee with a surety company
bond.

101

CITY ROADS AND PAVEMENTS.

102

AMERICAN SHEET-ASPHALT, ARTIFICIAL
AND NATURAL.

COMPARATIVE QUALITIES OF PAVEMENTS.

Asphalt pavement ranks first in extent of use and in
satisfactory qualities, being fairly durable, and cleaner
and less noisy than brick. Vitrified brick, the latest
and best types of wooden blocks and the more
recent bitulithic pavement, are its rivals for public
favor.

HISTORY OF ASPHALT PAVEMENTS.

The original pavements were made in Paris in 1854
and were formed of pulverized natural asphalt rock,
mined at different places in France and Switzerland
and Sicily. This rock is a natural combination of
eighty-eight per cent of amorphous carbonate of lime,
with twelve per cent of mineral tar or bitumen, form-
ing a bituminous limestone, and is generally used for
the comparatively small amount of asphalt pavements
in European cities.

A similar combination of sandstone and seven per
cent to thirteen per cent by weight of bitumen is known
as Kentucky sand-rock asphalt, and is used in some of
the cities of the United States, having an advantage
over the European bituminous limestone in being less
slippery.

103

CITY ROADS AND PAVEMENTS.

American Asphalt Mixture. — The artificial mixture
of sand and asphalt was first used in Newark, N. J., in
1870, and on Fifth avenue in New York in 1873,
though its first extensive use was in Washington in
1877. It nas since been laid in vast quantities in about
100 cities of the United States and is the best-known
form of asphalt pavement. The proportions and
methods have varied somewhat with the gain in accu-
rate knowledge and with the judgment of the builders
and with the local conditions.

This artificial mixture, which forms an artificial bitu-
minous sandstone, and also the Kentucky natural
sand-rock, give better results than the European rock-
asphalt, in that the sand which forms their greater
part, affords a better foot-hold, so that fewer horses
slip upon them and still fewer fall. Since 1883 Buffalo
has paved with sheet-asphalt 2 1 7 miles of street having
an average width of roadway of thirty feet, at a cost
of over eleven million dollars, while Philadelphia has
laid 235 miles; these cities alone having more than the
combined mileage of all the European cities. The
cities of the United States have in 1901, over 2,600
miles of asphalt-paved streets, stated by Major
J. W. Howard, engineering editor of Municipal Journal
and Engineer, to represent an investment of ninety-five
million dollars.

American Natural Sand-rock AspJialt. — To form
this pavement, the quarried rock is ground and heated
to 300° Fh., and taken to the work hot and spread
directly upon the clean concrete base where it is then
rolled and rammed into a compressed layer two inches
thick, no " flux " and no " binder coat " being needed.

104

HISTORY OF ASPHALT PAVEMENTS.

The sand-rock is sometimes used in combination
with bituminous limestone in proportion varying from
one and one to two and one.

BARTON STREET, BUFFALO, N. Y., October 5, 1901.
AMERICAN NATURAL SAND-ROCK ASPHALT, LAID AUGUST, 1891.

Pavement in perfect condition after ten and one-half years' use, during which time,
there have been no repairs of damage due to wear or weather.

There seems no good reason why the American
bituminous rocks should not be so systematically laid
as to give for the cities of the United States, pave-
ments which are as good as, or are better than, those
made for the cities of Europe, with their bituminous
limestones. Buffalo has had about ten miles of Ameri-
can sand-rock pavement since 1890-1892; Frank V. E.

105

CITY ROADS AND PAVEMENTS.

Bardol, M. Am. Soc. C. E., who has had charge as
chief engineer of the department of public works of all
the pavements of Buffalo for many years, states that
these " rock-asphalt pavements have required practi-
cally no repairs, although they have been laid from
seven to eleven years." This pavement was laid with
five-year guarantee on ten miles of fifty-one streets.
The needed repairs made since the guarantees expired,
have been confined to three miles of thirteen streets,
nine to eleven years old, at a total cost of an average
of three and eight-tenths cents per square yard of the
total area of these streets. The accompanying view
was taken in 1901, of a street which has had no repairs
since it was thus paved in 1891, and now shows good
results.

The average annual cost of repairs of this sand-rock
asphalt pavement is put by Mr. Bardol at one cent per
square yard, or one-third to one-fifth of the annual cost
of repairs to artificial sheet-asphalt. Front street in
San Francisco was paved with rock-asphalt in 1890
and has had an exceptionally heavy traffic, but it is in
perfect condition in 1902, having had no repairs during
eleven years of use.

In any northern city having either kind of sheet-
asphalt pavement, there will usually be during each
year two or three days or parts of days when the asphalt
will take a coating of ice upon which travel will be
difficult unless sharp sand is strewn upon the roadway,
but this is a small item in comparison with its many
advantages.

Appreciation of these advantages is shown in the
Borough of Brooklyn (of whose department of high-
ways, George W. Tillson, M. Am. Soc. C. E., who is a

1 06

VARIOUS COMPANIES.

recognised authority on " Pavements and Paving Mate-
rials," is chief engineer), where, during 1900, artificial
sheet-asphalt was substituted for, or laid upon, other
pavements on forty-three streets, equal in area to six-
teen miles thirty feet wide.

During the same year in the Borough of Manhattan,
sheet-asphalt was also laid upon or in place of other
pavements on sixty-four streets, equal in area to twelve
miles thirty feet wide, and in the Borough of the Bronx,
the same was done on fourteen streets, equal to four
and one-half miles thirty feet wide. Of one group of
twenty-four proposed paving works, seventeen were for
replacing or covering old pavements with sheet-asphalt.
See " Foundation " on page 1 13.

VARIOUS COMPANIES.

Since 1877 many different methods of construction
have been tried and a number of companies have been,
and some are still, before the public as competitive
builders of asphalt pavements. To do this successfully
and with certainty requires skill and knowledge which
can only be acquired by long and costly experience.
A great city may well employ experts who can specify
details and test materials and direct operations as has
been and is done in Washington and New York, but
cities of moderate size desiring to build a few blocks, or
a few miles, of asphalt pavement, should not attempt to
direct the details of construction and should not con-
sider other offers than those made by some of the few
great firms having the widest experience and possessing

107

CITY ROADS AND PAVEMENTS.

the necessary exact knowledge of all of the many essen-
tial details and having the best established reputations,
who can safely assume all responsibility for materials
and methods and can give an effective guarantee at
reasonable cost, for. a period of ten years; five years
not covering the critical time.

/pAf/C/PAL JOURNAL

COURT SQUARE, SPRINGFIELD, MASS. 1900
Rock-asphalt laid in front of City Hall in 1897 and repaired in 1898.

Sources of Supply. — There are many sources of sup-
ply of different asphalts, each varying from the rest and
each requiring its own treatment. Formerly that from
Lake Trinidad was assumed to excel all others for
forming the American asphalt mixture ; but large de-
posits were discovered in 1899 in northern Venezuela in
addition to Bermudez Lake in the Department of Sucre,
which alone is eight times the size of Lake Trinidad.
There is also in Venezuela another newly found deposit
of asphalt near the Gulf of Pavia in the Orinoco delta,
and another in the state of Jujuy in Argentina.

1 08

ARTIFICIAL SHEET-ASPHALT.

The American supplies of Kentucky sand-rock and
of California sand-asphalt are very large and are free
from international complications.

MATERIALS AND METHODS; AMERICAN ARTIFICIAL SHEET-
ASPHALT PAVEMENT.

Asphalt. — The full details of the materials and of the
methods of construction are omitted here, but those
which are given are based upon the practice during
1900 in the city of Washington, where closest atten-
tion is given to the subject by the engineer commis-
sioner of the District of Columbia, aided by Prof. A.
W. Dow, whose expert ability is widely known. Trini-
dad and Bermudez asphalts are used with results which
appear to be equally good. They are " refined " by
simply evaporating the water which occurs with them
in their crude state, and which forms about one-third
of the Trinidad Lake asphalt. This refined asphalt
must be softened to be useful as a paving cement, and
for this effect there is used a flux, which is generally a
heavy mineral oil or petroleum residuum.

Asphalt cement is the result of mixing eighty-one to
eighty-seven parts, by weight, of refined asphaltum,
with nineteen to thirteen parts of flux. This forms
the matrix of the asphalt pavement, constituting nine
and one-half to twelve and eight-tenths per cent, or an
average of nine and seven-tenths per cent by weight of
the asphalt mixture forming the wearing surface.

Asphalt cement of a softer consistency is formed by
mixing seventy-two to seventy-eight parts of refined
asphaltum with twenty-two to twenty-eight parts of
flux. This forms the matrix of the " binder," or about
five per cent of its total weight, or about eight per cent
of its bulk.

109

CITY ROADS AND PAVEMENTS.

Skill and care are required to vary the amount of
flux, so as to produce the uniform results necessary for
a reliable pavement.

Asphalt Mixture. — The "asphalt mixture" above
referred to is formed by mixing about nine and seven-
tenths parts by weight of asphalt cement with ninety-
one and three-tenths parts of hot sand and stone-dust
and limestone dust: the asphalt cement varying dur-
ing 1900 from a minimum of nine and five-tenths to a
maximum of twelve and eight-tenths per cent. This
limited amount of asphalt cement is less than the actual
voids in the sand, but the " mixture " becomes too plas-
tic, and forms waves when rolled, if the attempt is made
to use enough asphalt cement to wholly fill the voids
which are probably equal to at least five per cent after
it is rolled and finished.

Sand. — The careful and exact testing and propor-
tioning of the sands and the stone-dust and limestone
dust are a special feature of later practice. Formerly
it was only required that sand should be clean and free
from objectionable matter, but since 1894 it nas been
recognized that there are many varieties of sand, no
two deposits being alike and no deposit being uniform.
Samples are now taken constantly and are heated to a
proper degree of ,dryness, and then passed over a series
of screens to determine the relative proportions of each
size.

The composition of each of the various sands which
are available being thus learned by tests, two or more
kinds are combined in certain proportions, using great
care from day to day to obtain a perfectly uniform mix-
ture having a minimum of voids. These voids are in
turn filled, as nearly as possible, by adding a varying

1 10

MATERIALS AND METHODS, ETC.

proportion — averaging about one-tenth of the weight
of the sand — of finely powdered silica or fine stone-dust.

Limestone dust was formerly used exclusively for
this purpose, but during recent years powdered silica
or powdered mineral of any kind has been used instead
and has been thought to be better in some ways : but the
best practice in 1905 on Fifth Avenue in New York,
and in London, and in Omaha, and elsewhere, was to
use finely ground Portland cement, instead of stone-
dust, to fill the voids in the sand, thus getting better
results at slightly greater cost.

The sand best suited to making the asphalt mixture
has been found to consist of the following grades:

. Passing 100 meshes per linear inch 17 per cent.

Passing 80 meshes per linear inch 17 per cent.

Passing 50 meshes per linear inch 30 per cent.

Passing 40 meshes per linear inch 13 per cent.

Passing 30 meshes per linear inch 10 per cent.

Passing 20 meshes per linear inch 8 per cent.

Passing 10 meshes per linear inch 5 per cent.

It is most important that the two sizes first named
should be about equal in quantity and should together
be about one-third of the whole. In 1907, the best
results were had by the admixture of about 1 3 per cent.,
by weight, of Portland cement, making a mixture of
increased toughness, having about the following grada-
tions :

Passing 200 meshes per linear inch 13 per cent.

Passing 100 meshes per linear inch 13 per cent.

Passing 80 meshes per linear inch 13 per cent.

Passing 50 meshes per linear inch 24 per cent.

Passing 40 meshes per linear inch 1 1 per cent.

Passing 30 meshes per linear inch 8 per cent.

Passing 20 meshes per linear inch 5 per cent.

Passing 10 meshes per linear inch 3 per cent.

Bitumen 10 per cent, to 12 or 13 per cent.

The bitumen ranging in quantity with its vicosity
and the kind of surfaces of the grains of sand, so as to
coat all surfaces of all particles.

1 1 1

CITY ROADS AND PAVEMENTS.

This accurate proportioning of sand has been done
since 1894 by the best equipped companies, who have
learned the necessity, and the details, from experience
and who are therefore able to guarantee their work in
a way which was not formerly possible.

Crushed Stone for "Binder'.' — Crushed stone to
form the "binder" consists of any tough, hard rock
and is the total product of the crusher passing through
a one and one-quarter inch screen, with some of the
dust removed and with the coarse screenings of the
sand added.

Until recently,* the regular practice has been that
ninety-five parts of this by weight are mixed while hot
with about five parts of the softer asphalt cement
before described.

The amount of asphalt cement varies with the char-
acter of the stone, the hot asphalt cement being added
in the mixer until all faces of each fragment are coated,
but avoiding any excess of asphalt which might tend
to fill the voids between the fragments of stone.

FORMATION OF THE PAVEMENT.

Foundation. — If the street has never been paved,
the base of the proposed asphalt pavement is made of
hydraulic cement concrete four inches or six inches
thick. The usual practice is here shown and in the
table on page 56.

Surface
Binder

Con creTe

Asphalt PavemenT

* See page 114.

I 12

FORMATION OF THE PAVEMENT.

Much of the sheet-asphalt laid in the great cities has
been put directly upon old pavements of cobbles or of
stone blocks, of which the depressions may be filled with
hot crushed stone sprinkled with hot asphaltic cement,
or which may be merely re-set at points of subsidence
to restore the regular form, but which are usually re-set
at three inches lower grade and with the proper crown
in order to make room for the " binder " and the
" wearing surface " of asphalt, without having to raise
the manholes, car-tracks and curbs. The lower part of
Seventh Avenue, New York, was thus treated during
1901. The joints between the stones of the old pave-
ment should be three-fourths of an inch wide and
should be brushed and cleared for at least an inch in
depth to afford a firm hold for the " binder."

In some instances, stone blocks for a base have been
re-laid flat to give a lower grade, but this is not good
practice and has given poor results unless there is a
concrete base beneath the old blocks, as was the case
in New York on Broadway below Forty-second street
to Canal street which was thus treated in 1901.

Brick pavements built in 1887 have been used as
base for sheet-asphalt for many miles of streets in
Columbus, Ohio.

Old macadam roads have often been successfully
used as foundation for sheet-asphalt, and this may work
well until cuts are made for sewer and water and gas
connections when it will be difficult to restore the
pavement.

Binder. — The mixture of stone and asphalt which
has been described at page 112, is brought hot from
the mixer and is spread over the clean and dry base,
using rakes to give it a regular depth of two inches,

CITY ROADS AND PAVEMENTS.

where it is at once compressed to one and one-half
inches with a steam roller which may be slightly sprayed
with water to prevent adhesion.

A radical change in this "binder" is the most
important improvement in recent years, but it is not
generally adopted. The " honey-comb " character of
the " binder " has been a source of weakness which, in
Kansas City and Omaha during 1906 and 1907, has
been avoided by completely filling the voids of the
"binder" stone with the fine "asphalt mixture" de-
scribed on pages 1 10 and 1 1 1. The resulting stability
in the " binder course " permits that the " wearing sur-
face " may then be made i ^ inches thick instead of
the former 2 inches.

Asphalt work of all kinds should stop during rain,
or snow-fall, or freezing weather.

Wearing Surface. — This is formed of the " asphalt
mixture" which has been described on page no, and
must be brought hot from the mixer and should reach
the work with a temperature of about 280° Fh.: the
surface of the " binder " should be swept perfectly clean
to receive it, and it should be spread with hot rakes to a
uniform depth of two and one half inches of the loose
material, taking care to loosen that coming from near
the bottom of the cart which must be scraped clean
after every load. The loose layer is spread two and one
half inches deep to form a one and one half inch finished
surface, or three and one-third inches to form a two-
inch surface, which latter is much the better for heavy
traffic.

Rolling the Wearing Surface. — The " asphalt mix-
ture " is then rolled with a cold 1 2OO-pound hand roller^
the surface of which is constantly wiped with a piece
of oily cotton-waste to prevent adhesion.

114

FORMATION OF THE PAVEMENT.

After this rolling which is done quickly, the surface
of the asphalt is covered with finely ground dry mineral
dust (generally using dry hydraulic cement), which is
swept over the surface to give it the soft gray color
which is desired and to prevent the adhesion of the
five-ton finishing roller with which the " wearing sur-
face " is rolled until compressed to one and one half
inches or two inches in thickness and until the surface
is perfect. Cities are about equally divided as to which
of these thicknesses is used, as indicated in table on
page 56.

This rolling will usually occupy about one hour on
sixty feet length of pavement thirty feet wide.

The entire manipulation of the material, and espe-
cially its spreading and rolling, require skill and care
not only for the general features here described but
also for many other important details which are neces-
sary to secure good results.

CITY ROADS AND PAVEMENTS.

CARROLL STREET, BROOKLYN, NEW YORK, 1900.
Before covering cobble pavement with sheet-asphalt in 1900.

116

SHEET-ASPHALT PAVEMENT.

CARROLL STREET, BROOKLYN, NEW YORK, 1900.
After paving with Trinidad sheet-asphalt in 1900.

117

CITY ROADS AND PAVEMENTS.
GRADE AND CROWN.

The actual steepest grades existing in various cities
are shown in the accompanying table, in order that
those having doubts in any extreme case may examine
some of these grades and observe the results.

ACTUAL GRADES OF SHEET-ASPHALT.

CITY.

State.

Ft. per ioo
feet.

CITY.

State.

Ft. per ioo
feet.

Buffalo

N. Y.

e I

Pittsburg

Penn

Erie

Penn .

Salt Lake City

Utah

Grand Rapids

Mich. .

San Francisco

Cal. .

Hartford

Conn. ...

St. Joseph

Marion ....

Ohio

c.jc

Scranton ...

Penn. ..

New York
Omaha
Peoria. ....

N. Y....
Neb
Ill

7.2

Syracuse
Toledo
Troy .

N. Y. ..
Ohio....
N. Y. ..

7
5

7.C

/ 5

The crown used in various cities on level streets is
shown in the same way; it being borne in mind that
the least crown which will shed water makes the best
road for those who use it. See " Crown of Pavement,"
at page 30.

ACTUAL " CROWN " OF SHEET-ASPHALT.

CITY.

STATE.

C.^ JD

!'!§

U V- ^J

£ Z.£

CITY.

STATE.

i*£

j=U

CITY.

STATE.

i*£

§'* 5

Sll

Albany
Atlanta

N. Y ..
Ga

Fort Wayne. .
Grand Rapids

Mich „
Mich .

Muncie
New Orleans

Ind...
La

N Y

Penn

Peoria

Ill .

Buffalo
Charleston. ..
Columbus.. ..

N. Y .
S. C. .
Ohio. .
Ohio

5
4
6

4/4

Hartford
Houston
Jackson
Joliet

Conn .
Texas.
Mich .
Ill

4*
6
41A

Sandusky ....
Scranton
Springfield . . .
St Paul

Ohio. .
Penn .
Mass .
Minn .

Detroit
Elmira
Erie

Mich .
N. Y .
Penn

3%
4%
6

Mansfield . .
Meridan

Ohio. .
Conn .
Wis .

4%
ii

Terre Haute..
Toronto
Troy

Ind.. .
Ont . .
N. Y .

118

RIGID RAIL-BASE.
RAILWAY TRACKS IN ASPHALT-PAVED STREETS.

When railway tracks are laid in streets paved with
asphalt, there is wide variation in the manner of con-
struction next the rails : of fifty-two cities having this
condition to meet, all have, until recently, put some
other material than asphalt next to the rails : fourteen
using granite blocks, six using stone blocks, and four-
teen using vitrified brick.

The best practice in Buffalo, Rochester, Pittsburg
and elsewhere, is to use ninety-pound rails with nine-
inch or ten-inch webs welded in continuous lengths, and
placed on twelve-inch concrete base to insure rigidity:
the asphalt surface being then laid in contact with
the rails. See page 40.

The practice in Rochester since 1899 and in Pitts-
burg in 1901 has been to first place the heavy steel rails
accurately on line and grade with temporary supports,
and then to form the twelve-inch concrete base beneath
the rails ; ramming and tamping the concrete until it
rises against the rail-base and gives it a perfect bearing
at all points without having to use wedges.

COST OF SHEET-ASPHALT.

This varies widely with local conditions and with
the competion and can best be seen by reference to
the tables here and at page 56, showing rates with and
without concrete base and curbs.

REPAIRS: In 1905, the cost of repairs of asphalt pavement ten years
old averaged as follows per square yard of the entire pavement of that
age in each of the cities named: — Brooklyn, N. Y., $.043 ; Buffalo. N. Y.,
$.0028; Rochester, N. Y., $.0283; St Paul, Minn., $.0945; Toronto,
Ont., $.043; Washington, D. C., $.003; or a mean of a little over three
and one-half cents per square yard. Meantime the prices for a square
yard of re-surfacing were: — Brooklyn, $1.25; Buffalo, $1.23; Philadel-
phia, $1.07 to $i. 19; Rochester, $1.28; St. Paul, $1.65 ; Toronto, $0.89;
Washington. $0.98. In 1906, the repairs of Brooklyn asphalt pavements
cost an average of 2>l/4, cents per square yard over all area maintained
of all ages.

119

CITY ROADS AND PAVEMENTS.
PRICES FOR SHEET-ASPHALT PAVEMENT,

NOT INCLUDING BASE OR CURBS OR EXTRA WORK.

DATE

PLACE.

Guar-
antee.

No. of
Bids.

PRICK PER SQ. YD.

Max.

$2.17

2.31

2.00

Aver.

Min.

Oct. I, 1900.
Sept. 26, 1900.
Sept. — . 1900.
June 28, 1907.
June 3, 1908.
Nov. 25, 1908.

Albany, N. Y

IO yrs.

5 yrs.
10 yrs.

4
5
4
4
4

$I.9I
2.21
I.56

$i-34
1.97
1.40
1.18
1.40
2-45

Cincinnati, Ohio

San Antonio, Texas
Brooklyn, N. Y

Brooklyn N. Y

1.50

1.46

Aberdeen, Wash

(1 in. binder; 2 in. surface;

INCLUDING 6 INCHES OF CONCRETE AS BASE.

DATE.

PLACE.

Guar-

No. of

PRICI

: PER S

I.YD.

Max.

Aver.

Min.

Aug 7 1900

Aurora 111.

$1 Q7

$i 88

$1 8l

March 3 1901

Baltimore, Md

10 yrs.

2 27

2. 1 7

Aug. I 1900

Cortland, N. Y

lo yrs.

2 i C

2 14.

2.11

— . l8qq

Fort Wayne, Ind

10 yrs.

^•OJ

1.89

March 4, 1901

Houston, Texas

10 yrs.

2 QO

2 4.2

2. OO

^QQ

Joliet, 111

5 yrs

I r i

— t 1809.

Milwaukee, Wis

5vrs.

2 21

1-9^

— 1890

New Orleans, La

5 yrs

2. 11

— t 1898.

Oswego, N. Y

^ Yrs.

l.Q<,

July 20 1907

2 i C

June 4 1908

Erie Pa

2 O3

i 86

I. 7"\

June !<;, 1908.

Herkimer, N. Y

2.47

June 19, 1908

Ivnoxville, Tenn.

I Q?

1.86

I 80

June 23 1908

Louisville Ky

•J

I Q7

i 80

I 85

July n, 1908.

Washington, D. C

•3

1.48

Nov. 25, 1908

Elkhart, Ind

1.98

GUARANTEE.

It is now usual to require that the price paid for a
sheet-asphalt pavement shall include a guarantee that
it will be kept in good condition fora term of years and
delivered in good condition at the expiration of this
time : this term varies as is indicated by the records
of forty cities of the United States which had, on Jan-
uary ist, 1900, 757 miles of sheet-asphalt pavement:
of these, twenty require guarantee for five years and
twenty require a guarantee for ten years. Ten of the
latter have formerly required five years, but now require

120

GUARANTEE.

ten, showing a tendency toward a ten year guarantee.
Maintenance guarantees for long terms were required
for the sheet-asphalt pavements of Fifth avenue and of
Broadway, New York. Asphalt was laid in 1896-7 on
Fifth avenue with fifteen years' guarantee at the follow-
ing prices per square yard, including new concrete base :
from Ninth street to Fifty-ninth street, the cost was
$4.35 : from Fifty-ninth street to Eightieth street, $4.00:
from Eightieth street to Ninetieth street, $3.29: these
different rates indicating the expected effects of traffic
on the cost of maintenance.

Asphalt was laid in 1900 on Broadway, with fifteen
years' guarantee, from Fifty-eighth street to Fourteenth
street, upon new concrete base to Forty-second street
and upon the old stone blocks relaid flat upon two
inches of sand over the old six-inch to eight-inch con-
crete base below Forty-second street. The cost was
$5.37 per square yard.

Asphalt was extended in 1901 down Broadway to
Canal street, and cost $6.31 per square yard. This in-
cluded fifty-nine cents for relaying the old blocks flat
upon the old concrete base and also ten years' main-
tenance. This should include strewing sharp sand
when the pavement is slippery, as on Fifth avenue and
on all wood-block and asphalt pavements abroad.

The average cost of a guarantee in Buffalo is put by
F. V. E. Barclol, M. Am. Soc. C. E. (see page 56), at
three cents per square yard for the first five years and
fifteen cents for the second five years or eighteen cents
for ten years.

The probable cost of a guarantee for the third five
years would in some cases equal the cost of an entire
renewal of the surface.

In 1908 there appears to be a reaction from the desire for long-term guarantees
[ a growing feeling that both economy and equity call for less than five-year
iods.

121

and a growi
periods.

CITY ROADS AND PAVEMENTS.

122

SHEET-ASPHALT PAVEMENT.

I23

CITY ROADS AND PAVEMENTS.
CAUSES OF FAILURE OF SHEET-ASPHALT.

A reasonable amount of traffic tends to prolong the
life of a good sheet-asphalt pavement. When a pave-
ment begins to fail, the causes are probably to be found
in about the following order:

First. — Defective foundation, which has settled and
caused the hollows in which pools of water have stood
upon the surface of the asphalt until it has become
disintegrated.

Second. — Wearing surface too soft, or excess of
asphalt in binder, or dirt on surface of binder, either of
which may allow " wearing surface " to creep under
traffic and to form waves or rolls, in which the sheet of
asphalt mixture is thickened, alternating with hollows
where it has become thin.

Third. — Patches where the pavement has been torn
up for sewer and water connections and not well restored.

Fourth. — Surface cracks, which sometimes appear in
cold weather as a result of excessive contraction of the
surface, and which sometimes close and re-unite in
warm weather under the combined effects of warmth
and of passing wheels.

Fifth. — Excessive traffic which has worn off the sur-
face. This is the least common.

Sixth. — Lack of traffic, allowing the asphalt to
become spongy. The latter cause usually shows its
effects at the sides of the roadway next the curbs,
where there is least passage of wheels. The process
of failure may then be as follows :

The material composing the sheet of asphalt expands
slightly with the sun's heat, as all other substances do;
but unlike most other substances, it does not of itself
at once return to its original thickness when the heat

124

CAUSES OF FAILURE OF SHEET-ASPHALT.

is lost, because the asphalt becomes rigid as it cools,
and unless compressed by force, tends to remain in its
expanded form. In the center of the roadway, where
most of the wheels pass, the asphalt is at once re-com-
pressed, but at the sides this is not done so promptly,
with the result that there is a tendency to become
somewhat porous or spongy where there is little traffic.
When at last the asphalt has thus actually become
porous, water can permeate it, and this soakage of
water is helped by the fact that the surface-drainage is
toward the sides, where the material is most likely to
absorb some of it. Having thus absorbed ever so little
moisture, of course both heat and frost have increased

JEFFERSON AVENUE, BROOKLYN, igoo.
Destructive effects of gas leaks on sheet-asphalt pavement.

125

CITY ROADS AND PAVEMENTS.

effects upon the material, and ultimately it shows signs
of disintegration.

Seventh. — When a failure of asphalt is so complete
as to include several of these features, it will usually
be found that the pavement was built by some local
paving company, without previous experience, whose
bid should not have been considered and whose work
and guarantee proved to be equally worthless.

Eighth. — Disintegration of surface may also result
from defects in the mixture of asphaltum and flux or
from the laying of the pavement during freezing
weather; disintegration is frequently caused, espe-
cially in Brooklyn, New York and Kansas City, by the
escape of illuminating gas from leaky mains. The
hydrocarbons which are now used in these cities to
enrich and cheapen illuminating gas, are solvents of
asphaltum ; leaks of this destructive and tenuous gas
from the underlying main pipes are the direct cause of
failures like those shown in the accompanying photo-
graph of Jefferson avenue, Brooklyn, taken in 1900.

Disintegration of asphalt is also caused by the spill-
ing of kerosene by careless vendors, and by the drop-
ping of oil from the axle-boxes of street-cars.

Bonfires are sometimes built on asphalt pavements
with destructive effect, and this was done in one case
with a misdirected desire to celebrate the completion
of the pavement which it injured. Most of these causes
of failure are preventable by proper selection of the
builders or by proper care of the finished work.

There are many cases — among them Oswego, N. Y.,
as shown on the frontispiece — where no defects of any
kind have appeared during and after five years' use of
the pavement.

126

BLOCK ASPHALT PAVEMENT.

Asphalt blocks are used in many cities of the United
States, there being in 1900 the equivalent of ninety-five
miles of pavements, thirty feet wide. During 1900,
twenty-one streets, equal in area to three miles, thirty feet
wide, were thus paved in the Borough of Manhattan,
equaling twenty-five per cent of the sheet asphalt laid in
1900.

Washington, in July, 1900, had twenty-two miles of
such pavement, as compared with 141 miles of sheet-
asphalt. The asphalt blocks laid in 1900 were formed of
thirteen per cent asphaltic cement, ten per cent limestone
dust and seventy-seven per cent crushed gneiss, and
cost $1.77 per square yard laid, not including base.

The character of asphalt blocks has been much im-
proved during recent years and the proportions are now
usually about as above stated, except that crushed diabase
trap or basalt is generally used and with better results.
The materials are heated to 300° Fh. and are mixed
in a rotary mixer until all the faces of every particle of
the crushed stone are perfectly coated with the mixture
of asphaltic cement and limestone clust. The product
is then put in moulds twelve inches long, four inches
or five inches wide and three inches or four inches deep
and subjected to a pressure of two to two and one-half
tons per square inch and then slowly cooled in water.

This is done in a factory where the best results may
be obtained and the blocks are then shipped to their
destination, where they can be laid, like brick, in cold
weather, if necessary, by unskilled labor.

This last feature constitutes their chief advantage
over sheet asphalt. The blocks are laid in close con-

127

CITY ROADS AND PAVEMENTS.

tact, sometimes on gravel covered with sand, though a
concrete base is best, upon which the blocks are some-
times bedded in one inch of Portland cement mortar.
Asphalt blocks made as above described, have worn
well, but there are few cases where sheet-asphalt is not
preferable. The following table shows the prices of
recent pavements of this kind :

PRICES FOR BLOCK-ASPHALT PAVEMENT, FOUR INCHES THICK, INCLUDING Six
INCHES OF CONCRETE AS BASE AND FILLER IN JOINTS.

Date.

CITY.

State.

Guar-
antee.

No. of

bids.

PRICE PER SQ. YARD.

Max.

Aver.

Min.

Mar. n, 1901
Mar. 13, 1901

Annapolis .
Chillicothe.

Md..
Ohio.

5yrs.

2
15

$2 85
I 31

$2 80
I 17

$2 75
i 07

Mar. II, 1901

Pontiac

Mich.

5yrs.

c On 6 in.|
I gravel, j

2 40

Sept. 3, 1900
Feb. 18, 1901

Toledo
Toledo

Ohio.
Ohio.

5yrs.
5yrs.

18
3

3 25
2 55

2 32

2 45

i 95

2 25'

* (On sand base, seventeen cents less; on stone base, three cents less.)

A cheaper modification of block-asphalt, known as
the Leuba pavement, has been in successful use in
Neuchatel, Switzerland, since 1898, and consists of
blocks eight and three-fourth inches long, four and one-
half inches wide, and four inches to four and one-half
inches thick, but with the lower three-quarters of each
block made of hydraulic Portland cement and clean,
sharp sand in proportions of about one to four : this
concrete base being covered with a wearing surface
one and one-fourth to one and one-half inches thick of
compressed natural rock-asphalt: the two materials
being joined under heavy pressure, and the blocks
being laid with cement joints on a concrete base.

128

BLOCK-ASPHALT PAVEMENT.

BLOCK ASPHALT PAVEMENT, NINETY-SIXTH ST., NEW YORK, 1900.
Looking west from Third avenue to Park avenue. Paved in 1900.

129

CITY ROADS AND PAVEMENTS.

LIST OF CITIES HAVING BOTH SHEET-ASPHALT AND BRICK

PAVEMENTS.
Miles of each with preference.

CITY.

STATE.

SHEET-
ASPHALT,
Jan. i, 1900.

BRICK.
Jan. i, 1899.

PREFERENCE.

As-
phalt.

Brick.

Not stated.

Albany
Atlanta
Baltimore
Binghamton . .
Boston
Buffalo
Cleveland .
Columbus
Dayton

N. Y..
Ga
Md
N. Y...
Mass ...
N. Y...
Ohio ...
Ohio . .
Ohio ..
Mich . . .
N. Y ..
Penn ..
Mich ..
Mich . .
Penn ..
Texas ..
Mich . .
Ill
Ohio
Ohio

Wis ....

Minn ..
Conn . .
La ....
Ill

9 miles
2 miles
7 miles
5 miles
14 miles
217 miles
9 miles
15 miles
17 miles
22 miles
0.8 mile
II miles
7 miles
6 miles
3.4 miles
4 miles
0.4 mile
3 miles
I mile
1.5 miles

10 miles

13 miles
3.5 miles
23 miles
8 miles
235 miles
43 miles
I mile
12 miles
0.3 mile
9 miles
13 miles
3.5 miles
24 miles
21.6 miles
4 miles
141 miles

1 6 miles
2 miles
I mile
2 miles
I mile
7 miles
66 miles
74 miles
12 miles
24 miles
0.5 mile
6 miles
10 miles
4 miles
0.5 mile
7 miles
2.5 miles
3 miles
15 miles
6 miles

2 miles

5 miles
1.5 miles
59 miles
22 miles
120 miles
7 miles
6.5 miles
2 miles
1.5 miles
7 miles
3 miles
4.5 miles
8 miles
42 miles
8.5 miles
I mile

Elmira

Fort Wayne ..
Grand Rapids.
Harrisburg . . .
Houston

Joliett

Mansfield

Milwaukee . . -

Minneapolis..
New Haven ..
New Orleans .

On over
4 per
cent
grades.

Philadelphia..
Rochester
Sandusky
Scranton
Springfield . ..
St. Joseph ...
St. Paul
Terre Haute..

Penn ..
N. Y ..
Ohio ..
Penn ..
Mass
Mo ....
Minn . .
Ind
Out
Ohio ..
N. Y ..
D.C....

Toledo

Troy

Washington ..

Total

920 miles

560 miles

(Compiled by Willis Fletcher Brown, consulting engineer of Toledo, Ohio.)

130

BITULITHIC PAVEMENT.

During 1901, a practically new form of pavement
with the above name has attracted much attention and
has come into use at widely separate places ; its favor-
able discussion in the Engineering News of January
30, 1902, and in the Engineering Record of the same
date, confirmed many in the opinion that this \vas a
new factor in the solution of the paving problem.

Time has verified this opinion, and the extent of the
use of bitulithic pavement throughout the United
States and Canada, during the past five years, has been
remarkable. It has been adopted by one hundred
cities in territory extending from Maine to Oregon,
and from Nova Scotia to Louisiana, thus giving it the
tests of use in the extremes of the varying climatic
conditions of the continent, and with evident success
as showrn by the fact that of thirty cities which have
contracted for nearly a million square yards to be laid
during 1906, twenty-one have already used it and know
its qualities from actual experience.

The former bituminous or "tar" pavements have
usually been formed of sand, the fine grains of which
have no other stability or structural strength than is
derived from the matrix of asphalt or of coal-tar in
which they are embedded: or they have consisted of
tarred fragments of stone with twenty per cent or more
of void spaces, generally placed without systematic
heating and mixing.

BITULITHIC PAVEMENT.

NORTH JAMES STREET, ROME, N. Y.
Laying bituminous foundation or base.

WOODLAWN AVENUE, TORONTO, ONT.
Laying Bitulithic surface.

BITULITHIC PAVEMENT, 1902.
I32

DETAILS.

Bitulithic pavement is formed of trap rock, or other
tough rock, crushed and screened to fragments varying
in size from two inches down to the dust, and com-
bined in such proportion of sizes that the final spaces
between the fragments of rock do not exceed ten per
cent. This means that the fragments must be in actual
and firm contact with each other and that the addition
of ten or twelve per cent, by weight (twelve to sixteen
per cent by bulk), of bituminous compound will fill the
remaining voids and make a solid and impervious
mass.

When this is accomplished, the result must be a
pavement which water cannot penetrate and which
should support the passage of traffic without abrasion
of the fragments upon each other and without the
bituminous filler being exposed to action of the
weather.

It is obvious that the success of the pavement will
be dependent upon the care which is used in the selec-
tion of the materials and the skill and thoroughness
shown in combining and placing them, and that these
features are as important as for an asphalt pavement.

BASE.

The choice of base for bitulithic pavement depends
upon the character of the material over which it is to
be laid. If the soil is gravel, or can be rolled solid, a
bituminous base can be used as foundation, making it
of crushed stone or slag two to three inches in size,
laid to a uniform depth of four to six inches and rolled
with heavy steam rollers, following this by spreading
a coating or binder of hard, waterproof, bituminous
cement. If the soil is sand, or cannot be rolled solid,

133

CITY ROADS AND PAVEMENTS.

the usual base of hydraulic cement concrete (page 42)
is advisable, with the addition that, in order to give
closer bond with the bitulithic surface, the top of the
concrete should be roughened by tamping fragments
of crushed stone into the concrete while it is plastic
and partly embedding them in its mortar before it sets.
If the street to be improved has been paved with
macadam, or with asphalt, brick or asphalt blocks, or
any firm foundation, the use of bitulithic upon it is
practicable.

TOP.

Upon the base, prepared as above, the "wearing sur-
face" is spread and is compressed while hot with heavy
rollers to a final thickness of two inches : this "wearing
surface" is formed of the best available crushed rock,
preferably hard limestone, gneiss or trap, varying in
size from a maximum of one or one and one-half inches
down to an impalpable powder. The whole material
is then heated and dried in rotary drums and then
screened in rotary screens, separating it into six or
more sizes, and tests are made to determine the proper
proportions of the different sizes of fragments and of
sand and of crusher-dust which will produce the dens-
est mixture having the smallest percentage of voids.
These proportions by weight of each size are then run
into a mechanical mixer at a temperature of 250° Fh.
and are then combined with an acturately-weighed pro-
portion of heated bituminous cement, which is carefully
determined to be sufficient in quantity to fill all final
voids, coating all faces of all particles of stone and of
sand and of dust, and also providing a slight surplus
of "filler." When thoroughly mixed, it is hauled to
place on the street and is spread and rolled while hot

134

DETAILS.

in the same manner as is asphalt, but by use of a
twelve to twenty-ton three-wheeled steam roller of the
road-roller type (pages n and 14), this having much
greater compressive effect than the five to ten-ton two-
wheeled asphalt-roller. The effect of this heavy rolling
is to compress the bitulithic materials to the required
thickness of two inches, crowding the bitumen into all
the voids, forcing out all air-bubbles and making the
surface as dense as possible.

NON-SLIPPERY SURFACE.

Upon this surface, filling its irregularities and mak-
ing it sticky, there is then poured and rubbed a coating
of quick-drying bituminous cement, heated to 250° Fh.
and over this is spread about a quarter-inch layer of
small stone chips which are rolled and forced into
the sticky coating forming a final wearing surface:
these chips being larger in proportion as the grade is
steeper, so that a good footing is given for horses on
steep grades.

WIDTH, GRADE AND CROWN.

Bitulithic pavement usually extends from curb to
curb, the widest being 1 20 feet on Lindell Boulevard,
St Louis, Mo., and the narrowest being sixteen feet on
State Road leading south from Cleveland, Ohio, all
widths between these extremes being used in various
cities.

The crown generally adopted on flat grades is one-
fourth inch for each foot of width of street exclusive of
car-tracks, which is more than has been considered safe
for pavements not having a gritty surface. On steep
grades, the crown is made one-eighth inch to the foot
of width of street.

135

CITY ROADS AND PAVEMENTS.

FORD STREET, PORTLAND, OREGON.
Bitulithic pavement laid in 1905.

BOWDOIN STREET, BOSTON, MASS.
Bitulithic pavement laid on 13 per cent grade in 1902.

136

OPINIONS.

The steepest grades are eight to twelve feet per 100
on Harvey Street, Pawtucket, R. I., ten to thirteen feet
per 100 on Bowdoin Street, Boston, Mass., (see page
136) and ten to fifteen feet per 100 on Park Hill,
Yonkers, N. Y.

COST.

The bitulithic pavement has been in actual use
since January, 1901, and the favorable opinions which
were then expressed by skilled road-builders as to its
durability and value have so far been justified; all of
the cities which then experimented with it having
since annually used it in increasing quantities, their
success leading many others to follow their example:
100 cities having laid 194 miles of 3o-foot pavement,
or three and one-half million square yards, at prices
now ranging from $2.00 to $2.50 per square yard,
exclusive of grade and usually including five years
guarantee.

OPINIONS.

Among those who first expressed favorable opinions on the value of
Bitulithic pavements were C. A. Brown of Cambridge, Mass., then
president of the Massachusetts highway association, and R. A. Jones,
then vice-president of that association, which has long been a recognized
leader in the good-roads movement. Prof. A. W. Dow of Washington,
D. C., who expressed the opinion, based upon what he then knew of it,
that it exceeded in good qualities any other pavement that he had seen
laid. Chas. W. Ross of Newton, Mass., a former State highway com-
missioner of Massachusetts, commended it most strongly to the conven-
tion of supervisors of New York State at their annual meeting at Albany
in January, 1902, while the 1902 edition of " City Roads and Pavements"
quoted these favorable opinions and added its own. To these may be
added many similar expressions, and among them that of M. Girard,
Commissioner of France to the St. Louis Exposition in 1904.

With such weighty opinions from unbiased experts, confirmed by the
results of actual use, it is evident that this pavement is a factor to be
considered in future projects for city streets..

137

BROKEN-STONE ROADS.

In the recent wide discussion of " Good Roads," mac-
adamizing or some more or less similar arrangement of
small fragments of broken or crushed stone, is most
often spoken of, and the general reader who has given
no special attention to the subject further than to read
the many articles which appear in papers and maga-
zines is most likely to conclude that some such con-
struction suits all conditions and localities, though it is
really best suited and most used for highways outside
of the business parts of cities.

Within the past eight years, there has been an in-
creased use of broken stone roads for residence-streets
of cities, resulting from the examples of good work given
by the governments of various states in building high-
ways by state aid outside of corporate limits, and thus
familiarizing city officials with the methods by which
the best roads of this kind can be built and maintained.

This is especially manifest in the cities of Massa-
chusetts, where over 200 miles of macadamized streets
have been built since 1894 'in the cities of Brookline,
Cambridge, the Newtons, Medford and Springfield, as
well as 240 miles in Boston. Also in many cities of
New York State, especially in a section of Buffalo, near
Delaware Park. The city of Greater New York leads
in this as in all things, the five Boroughs having on

EXTENT OF BROKEN-STONE ROADS.

January ist, 1901, the following stated miles of mac-
adam streets and boulevards. Manhattan, eighty-two
miles ; The Bronx, ninety-one miles ; Brooklyn, eighty-
two miles; Richmond (Staten Island), 183 miles;
Queens (on Long Island), 388 miles ; Central Park,
nine and a half miles (all telford, 1869 to 1878); Pros-
pect Park, six and a half miles ; Greenwood, twenty
miles; or a total of 862 miles of broken-stone roads
within the city, practically all but forty-five miles built
since 1894.

The building of rural roads by state aid was begun
in 1893 by the State of New Jersey, which paid one-
third of the cost of construction ; followed in 1894 by
the State of Massachusetts, which paid three-fourths of
the cost, and by Connecticut in 1895, which paid two-
thirds to three-fourths of the cost, and by New York
State in 1898, which paid one-half of the cost: the bal-
ance in each case being paid by the towns or counties.
In Maryland, the state aids the counties by making
their surveys and plans and directing the improvements.

Under these systems, the roads most considered and
most built have been of the two principal types of con-
struction known as the macadam and the telford, though
many miles of gravel roads have also been built and
many miles of highways in each state named have been
merely improved by forming and draining the natural
materials as found, with the idea that this work may be
later continued by putting broken stone upon the road-
ways thus begun.

ROCK FOR ROADS.

Trap. — The three states first named are fortunate
in having many formations of good rock for road con-

139

CITY ROADS AND PAVEMENTS.

struction, while New York State is mainly limited for
the best grade of rock to the diabase-trap or dolorite
formation lying on the Hudson River in Rockland
county, just north of Nyack and opposite to Sing Sing
or Ossining.

This lies ten miles north of the limit of the proposed
Palisades Reservation, is more accessible by canal boat
and by railroad than any part of the Palisades and con-
tains enough material of the best grade to macadamize
all the roads in the state. The many quarries of New
Jersey and Connecticut are also available for roads in
New York as well as in those states. There was also
discovered in 1901 a large isolated mass or "plug" of
trap rock, near Schuylerville, N. Y., about twenty miles
north of Albany, lying close beside the Champlain
canal and the railroads. Other similar formations have
been found in Clinton county by the State Geologist,
Professor F. J. H. Merrill. Trap rock is the best for
road construction, in that it has no true cleavage and
breaks irregularly with toothed surfaces, and is tough
and does not easily grind into dust and mud. Its spe-
cific gravity is great, so that its dust does not blow so
readily as that of limestone.

Porphyry is ranked next, but it is not common and
the supply in New York State is limited to Lake
Champlain.

Quartzite, and siliceous quartzite are more common
and in some cases make very good road-material, but
should be avoided if possible.

Granite of some varieties is a good road-material, in
proportion as it contains but a small amount of mica
and of quartz, and is not weathered.

The same is true of gneiss and of syenite, which are
granitic and of which large and accessible formations

140

ROCK FOR ROADS.

exist at Little Falls, on both sides of the Mohawk river,
where there are unlimited quantities, close to the Erie
canal and the railroads. Throughout Westchester
county, N. Y., there are many and varying ledges of
gneiss, some of which are tough and good, but many
of them carry an excess of mica and of quartz and of
feldspar, and crumble readily, especially when weath-
ered, and are unsuitecl to road-making.

Limestone usually binds well and readily and, if
unusually hard, makes a good road. Well-known
examples of the best limestones, which have been and
are much-used for road-making, are the Tompkins'
Cove stone and the Clinton Point stone, quarried on
the Hudson, forty miles and seventy miles from New
York, and the Bethlehem stone, near Albany, N. Y.,
and the Jammerthal flint-limestone, quarried in the
suburbs of Buffalo, N. Y.

Some of the other limestones, which also bind readily
and have been used for roads, contain an excess of
lime and crush under heavy traffic, and form a light
and impalpable dust, which is most objectionable to
residents as well as to drivers. This dust is only
avoided by keeping these roads constantly wet, entail-
ing an expense for sprinkling which proves to be more
costly than to use a better stone which does not form
such dust.

Soft limestones form a good lower course to be cov-
ered by a harder wearing-surface or top course. The
cementing action, so called, of limestone, is purely
mechanical, but it serves to firmly bed the fragments
and to prevent them from rubbing and wearing against
each other. The use of limestone screenings is dis-
cussed at page 1 60, under "Quality of Screenings."

141

CITY ROADS AND PAVEMENTS.

Sandstone or " bluestone " road, built in Ulster county, N. Y., in 1900.
142

COBBLE-STONES.

Sandstone is only suited for use where better rock
cannot be readily obtained, and then only for the base
course where it should be covered by a wearing sur-
face of trap or other tough rock. An exception to this
must be made in favor of the "blue-stones" of Ulster
county, and the five adjacent counties of eastern New
York, which are true sandstone and are peculiarly
tough. The Ulster county stone binds readily with its
own screenings, and has been used to form the whole
material of good six-inch macadam roads, which stand
well under moderate traffic and are here shown.

Various Kinds of Rock. — Broken stone roads can
be well made with various rocks, requiring varied
treatment to suit the conditions. The many rocks and
the details for their successful use, can nowhere be
better studied than in New York State, which probably
contains as great a variety of geologic formations as
any other equal area in the world.

IMPORTANCE OF UNIFORMITV.

In the selection of material to be crushed for road
metal, uniformity in character is of the first importance;
material which is uniformly of a second grade being
preferable to a mixture of better and worse. Such a
mixing of fragments of hard and soft rocks results in
quickly crushing the softer pieces and then exposing
the harder pieces to excessive shocks from passing
wheels.

COBBLE-STONES.

Rounded cobble-stones gathered from the fields and
lake shores, make a very poor wearing surface for a
road, whatever their composition.

CITY ROADS AND PAVEMENTS.

Being worn by action of water or ice into rounded
forms, all of the fragments crushed from them have at
least one curved or water-worn face. These curved
and polished faces prevent the adjacent fragments
from coming to a solid bearing in a road. They will
always be likely to rock or slide under passing loads,
and thus loosen all the fragments which touch them.

Further, these rounded cobble-stones which were
strewed broadcast over parts of the country during the
glacial period, came from the most widely different
localities in the northern part of the continent and
include all varieties and degrees of hardness.

Granite, syenite, quartz, limestone, flint and slate
were found to make up one-tenth of a mass of them, of
which the remaining nine-tenths were sandstone, of
which at least one-half were so disintegrated or weather-
worn— so " rotten," as the workmen call them — as to
be worthless for any purpose: for road-surface metal
they are worse than worthless, as their only effect is to
destroy the good material with which they chance to be
mixed.

Crushed cobble-stones may be selected to form the
lower or base course, if nothing better is available, by
rejecting all which are inferior and by selecting, to be
crushed and screened, only the hardest and best.

In some regions where half or more of the many
boulders, large and small, were found to be of good
granite, these have been crushed to form the top
course. In some cases, it has proved economical to set
up two crushers near together, one crushing, for the
top, the best granite boulders selected from each wagon-
load as brought from the fields, and the other crushing
the less desirable ones for the lower or base course.

144

TESTS OF ROAD METAL.

TESTS OF ROCK FOR ROAD-MAKING.

The various rocks available for road-making are
compared as to their relative endurance, by subjecting
similar sets of samples of each kind to similar abrasion
in machines like that here shown, which was devised
by Deval in 1878. Each set of samples consists of
eleven pounds, or five kilograms, of roughly cubical
selected fragments, none smaller in any way than one
and one-quarter inches, nor larger than two and one-
half inches. These are cleaned, washed, dried and
accurately weighed, and enclosed in one of the cylinders
and tightly sealed. Similar sets of samples are put in
each cylinder and the whole machine is then slowly
revolved at the rate of 2,000 revolutions per hour for
five hours, or until a cyclometer registers 10,000
revolutions.

The fine dust worn from each set of samples is then
saved for cementation tests, and the fragments are
washed, dried and again weighed : comparison of the
percentage of loss of each set indicates the relative
endurance which is also to be seen by examining the
fragments of rocks before and after testing.

The department of civil engineering of Columbia
University has a most complete equipment with which
Prof. Wm. H. Burr, M. Am. Soc. C. E. has caused to be
made many useful tests of road materials, and Harvard

146

TESTS OF ROCK FOR ROAD-MAKING.

is similarly equipped: the testing laboratory of the
college of civil engineering of Cornell University,
directed by Prof. C. L. Crandall, M. Am. Soc. C. E., is
also fully equipped and makes many tests of stone and
bricks for pavements, as does the highway division of
the Maryland geological survey at Johns Hopkins
University, directed by Harry Fielding Reid by whose
courtesy the plates of machines and samples are here
given. Records of similar tests of various rocks have
been made and published by the highway commission
of Massachusetts, by the highway division of the
geological survey of Maryland, by the U. S. Office of
Public Roads at Washington, by the State Geologist
of New York and by the State engineer of New York
and these records are useful guides in selecting stone
for road-construction.

The U. S. Office of Public Roads at Washington,
Logan Waller Page, Director, has a most complete
equipment and system for analyzing and testing mate-
rials for road-building ; making chemical analysis when
necessary and preparing thin, polished, transparent
sections of rock for microscopic examination and for
rapid macroscopic measurement of quantative composi-
tion, as well as making the tests as to toughness, hard-
ness and cementation, as described on page 146, and
by improved methods.

Bulletin No. 31 entitled " Rocks for Road- Building"
by Edwin C. E. Lord, issued August 8, 1907, gives
valuable details of methods, qualities and classification.

CITY ROADS AND PAVEMENTS.

MARBLE.

HARD LIMESTONE.

DIABASE TRAP ROCK.

ROCK FRAGMENTS BEFORE AND AFTER ABRASION TEST.
Two-thirds natural size.

148

TESTS OF ROCK FOR ROAD-MAKING.

The following table shows the results of 100 tests of
the six kinds of rock most used in Massachusetts and
New York:

KIND.

Number of
tests.

PER CENT OF Loss BY ABRASION.

Max.

Min.

Mean.

Diabase trap.

35
24

I 2
12

4-31
6.68

4-3°
5-9°
6-57
6.69

1.40

2-33
2.23

1.97

J-73
1.71

2.28

4-34
3-52
3-63
4.01

3-56

Limestone.

Granite

Quartzite . .

Gneiss

Sandstone

(The last item includes Medina Sandstone at 2.29 and Ulster " Bluestone " at 3.71.)

Several local rocks are sometimes available of which
there may have been no tests, but experience will
usually enable a selection to be readily made of the one
which will give the best results. The rock which will
bind the most readily will probably be the least durable,
and it may be more economical to make a long haul of
a good rock than to use one which is near at hand, but
which will soon need renewal.

MOTOR-TRUCKS TO HAUL STONE.

During 1908, gasoline motor-trucks costing about
$4,000 each and capable of carrying 5 tons of crushed
rock at 8 miles per hour and returning empty at 10
miles per hour — or doing 1 50 to 200 ton-miles daily —
have been used by some road-builders who report a
saving of one-third of the cost of similar work done on
the same roads by horse-drawn wagons, costing, with
driver, 40 cents per hour.

149

THE MACADAM AND THE TELFORD SYSTEMS.

About a century ago Macadam preached and prac-
ticed a gospel of good roads for England with an
effectiveness which our leagues of to-day can only hope
to imitate in the United States.

England had long had roads of broken stone, and
the use of this material was not peculiar to Macadam's
method; but he was the first to establish rules of con-
struction which were generally accepted, and under
them were built 25,000 miles of road which formed a
network all over England; so that his name has come
to be associated with broken stone as a road material,
although Telford, who came twenty-five years later,
used the same material but in a different manner. In
Macadam's talk to committees of Parliament and to his
workmen, he always enforced the idea that the whole
secret of making a good road was to keep its earth-bed
dry ; that the ground was the real road and must bear
the weight of the stones, as well as of the traffic, and
that the subsoil, however bad, would carry any weight
if made dry by drainage and kept dry by an impervious
covering.

In this requirement Telford and all skillful road
makers fully agree.

This dry roadbed, Macadam covered with a layer of
road metal of a finished thickness of five to ten inches

CITY ROADS AND PAVEMENTS.

(varying with the weight of traffic), composed of small
angular fragments of the hardest and toughest rock,
broken to a uniform size, as nearly as possible to one
and one-half inch cubes, or six ounces each in weight.
No dimension larger than two inches was allowed, and
any piece too large for a workman to put in his mouth
was to be broken again.

In the matter of Telford's foundation for a broken
stone road and Macadam's omission of it, there are
wide differences of opinion and of practice: French
and English engineers generally omitting the telford
foundation and many American engineers seeming to
tend toward the same practice, or to limiting the use of
telford foundations to those portions of roads where the
earth subgrade is not firm.

The latter practice is best because where the sub-
grade is firm, the telford base serves as an anvil upon
which the shocks of traffic break the fragments which
form the surface. Where the sub-grade is dry and well
drained, the telford base has the effect to more quickly
remove the moisture which helps the binder to bed and
to hold the surface-fragments. Sprinkling is done in
dry weather to supply this moisture and without it the
road " ravels." This raveling will occur sooner on a
dry section of telford road than on a similar section of
a macadam road, but this difference is not so important
when the roadway is a city street which is sprinkled
and shaded. When the sub-grade tends to being wet,
the telford base is desirable as a foundation, and costs,
when local stone is at hand, thirty to thirty-five cents
per square yard.

152

TELFORD ROADWAYS.
COST.

As to the relative cost of the two methods, it is usual
that telford is somewhat more expensive, but the fol-
lowing does not so show.

At Somerville, N. J., on October 22d, 1900, proposals
were received for two miles of eight-inch macadam and
for six miles of ten-inch telford and macadam, each of
trap rock, each twelve feet in width, and each including
about 2,000 cubic yards of excavation per mile : the
prices were in cents per square yard:

Average at
Max. Min. 14 bids.

For eight-inch macadam roadway complete. . 83 50 62
For ten-inch telford roadway complete 83 50 66

For the stone roadways only, not including grading
and drainage, for eight roads built in New Jersey, dur-
ing 1900, the average costs were:

For four six-inch macadam roads, fifty-three cents
per square yard ; for four eight-inch telford roads, fifty-
one cents per square yard.

During 1901, as stated in the report of Henry I.
Budcl, commissioner, nine eight-inch macadam roads
averaged seventy-seven cents per square yard and three
eight-inch telford roads averaged sixty-one cents per
square yard.

TELFORD ROADWAYS.

The general requirements for construction of telford
roadways are similar in the different states with the
exceptions which will be named: the earth roadbed
or subgrade, is excavated and carefully rolled and
formed as for a macadam road, conforming to the pro-
posed cross-sections and twelve inches below the estab-
lished grade of the finished road.

153

CITY ROADS AND PAVEMENTS.

On this subgrade are then placed by hand the stones
forming the telford foundation, which may vary in size
as shown below: each stone must be set vertically
upon its broadest edge, lengthwise across the road and
forming courses and breaking joints with the next
course, so as to form a close and firm pavement. The
stones are then bound by inserting and driving stones
of proper size and shape to wedge the stones in their
proper position. All projecting points are then broken
with a sledge or hammer so that no projections shall
be within four inches of the finished grade-line. The
telford foundation is then rolled with a steam roller of
ten or more tons weight, until all stones are firmly
bedded and none move under the roller. All depres-
sions are then filled with stone' chips not larger than
two and one-half inches, and the whole left true and
even and four inches below the line of finished grade
and cross-section.

A good workman will average about twenty minutes
in setting a square yard of this telford foundation,
which may be formed of any kind of quarried rock
which is most available : cobble-stones are not suitable.

The practice in 1901 in the states named is here
shown :

SIZES OF STONE FOR TELFORD FOUNDATION, IN INCHES.

STATE.

DEPTH, AS

SET ON
EDGE.

WIDTH, AS

SET.

LENGTH,
SET ACROSS

ROAD.

REMARKS

Max.

Mm.

Max.

Min.

Max.

Min.

New Jersey.
Mass
Conn

8
6
8
8

5
8
6

4
10

4
6
4

6
8
6

Alternate end-stones
double length.
Two inches gravel rolled
on sub-grade as base.
Macadam covering
formed in one layer.
Used only on unstable
ground "as foundation
for macadam.

New York . .

154

CITY ROADS AND PAVEMENTS.

The requirements for forming the four inches or six
inches of broken stone roadway upon this telford
foundation are the same as for regular macadam.

Of the mileage of broken-stone roads built by State
aid during 1900, telford foundation was used for one-
sixth in New Jersey, one-seventh in Connecticut, one
thirty-eighth in Massachusetts and none in New York.
During 1901, New Jersey used the same proportion as
in 1900.

NEED OF BINDER WITH BROKEN STONE.

Macadam required that the layer of regular frag-
ments should be spread on the earth roadbed, to be con-
solidated by the wheels of passing vehicles, without the
aid of any fine material or of " binder " of any sort.

This requirement was impracticable and probably
could not be enforced, and experience has shown that
it is not desirable that it should be enforced.

Such fragments, loosely piled or spread, have about
forty-six to forty-eight per cent of void spaces, and will
pack by rolling to about three-fourths of their thickness
when loose.

The consolidation of perfectly clean, regular, angular
fragments of trap rock, free from screenings or binder
of any sort, was thoroughly tried by Mr. Grant in Cen-
tral park, New York city, in 1860. A piece of road
covered with Macadam's ideal road metal, free from
binder, was rolled for several days, until the fragments
\vere worn and rounded, without firm consolidation
being effected, and this experience has been recently
repeated elsewhere.

Road material which can be packed without binder
must be of a poor quality, which will supply itself

156

MODES OF USE OF BINDER.

with binder by readily grinding into dust and small
pieces.

Telford's system differed radically in that he first
covered the earth roadbed with a rough pavement of
firmly set stones, and that the wearing layer of broken
fragments varied in size, and that a binder of fine
material was spread over the surface to help in its
consolidation.

MODES OF USE OF BINDER.

This is one of the most important features of mac-
adam road construction, and the different modes which
produce successful results on State roads are therefore
given in detail.

In England there are now various methods in use,
but as a general thing Macadam's method of using
perfectly clean fragments of hand-broken rock is not
now followed. The commonest practice seems to be
to use twenty-five per cent of binder called " hoggin,"
consisting of a mixture of loam, coarse sand and small
gravel. This "hoggin" being worked into the layer
of broken stone by flooding the roadway with water.

In France, where the greatest care is given to road
construction and maintenance, twenty-five per cent of
sand is generally used with the broken rock as a binder.
This is washed to fill the voids between the fragments
of rock, with a final addition of chalky dirt and water
to fill the voids in the sand. See quotation on page
169.

In the United States, where little or no stone is now
broken by hand, experience has satisfied most Ameri-
can engineers that the roads \vear better and have less
dust and fewer loose stones if binder is put upon the

157

CITY ROADS AND PAVEMENTS.

consolidated layer of crushed stone to fill the spaces
which remain after rolling, and this binder is usually the
stone dust and the small fragments from the crusher
which pass through the circular holes, half an inch in
diameter, of a revolving cylindrical screen. The use
of binder is the same whether the construction is tel-
ford or macadam.

In New Jersey, after the lower course of broken
stone has been rolled until compacted, trap rock screen-
ings one-half inch to dust, free from loam or clay, are
spread over the lower course in a uniform layer and
the course is again rolled until the stones cease to sink
or creep in front of the roller ; water being applied in
advance of the roller if required. The same treatment
is given to the top course. This is then covered with
a mixture in equal parts of three-fourths inch crushed
trap and of half inch trap screenings, properly mixed
and spread in sufficient thickness to make a smooth and
uniform surface which is rolled until hard. Sandy loam
is used with good results upon some New Jersey roads.

In Connecticut, after each of the two courses has
been rolled until solid and firm, dry trap rock screen-
ings not larger than one-half inch are scattered over
the surface so as to fill all interstices and the roller is
then run over the road to shake in the dust.

The sprinkler is then used to wash in the screenings
and then more screenings are added, rolled dry and
then sprinkled, and these processes are repeated for
each course until all interstices are completely filled.
When the top course has thus been made firm and
smooth, it is then covered with one inch of screenings
to form a wearing surface.

158

MODES OF USE OF BINDER.

In Massachusetts, the lower course is thoroughly
compacted by rolling, but no screenings or filler are
spread or used upon it. After the top course has also
been thoroughly compacted by rolling, screenings of
the same kind of stone which forms the top course are
laid on in just sufficient quantity to cover the stone
and are then watered and rolled until the mud flushes
to the surface. The screenings are not treated as a part
of the wearing surface but are used simply to hold the
larger stone in place, using as little as possible.

In New York, the screenings used as filler are usu-
ally limestone when the road-material is brought from
a distance, but are often the product of the local crushed
stone when local rock is fit for use ; sometimes local
rock and its screenings are used for the lower course
only, but when possible they are used for the top also.
In some cases when local granitic rocks are used, the
screenings for the top course are caused to bind prop-
erly by mixing an equal amount of limestone screen-
ings with granitic screenings. In many cases during
1904 and later, the cost was much reduced, and good
results were obtained, by filling the lower course with
local sand, or with sandy loam only, or by mixing these
with the granitic screenings. Trap and granite screen-
ings are limited to a maximum size of one-half inch,
but those of softer rocks to three-fourths inch. After
the lower course of stones did not creep or weave
ahead of the roller, the dry sand or screenings were
spread uniformly to a depth of a half-inch or more and
then rolled dry and swept with rattan or steel brooms,
and these processes repeated until the lower course
was filled. Water is not necessary for filling the lower
course, but may be used, when the soil is gravelly, to

159

CITY ROADS AND PAVEMENTS.

hasten the work, using 600 to 1000 gallons per 100
feet of 1 6-foot road, or until all voids are filled, leaving
the surface of the stones free from screenings. See
page 175.

The top course is then spread and rolled and treated
in the same manner in sections of about 300 feet length,
water being freely used and the rolling continued until
a grout has been formed of the stone-dust and water
and until a wave of this grout is pushed before the
wheels of the roller. After this effect is produced,
screenings are spread and rolled, leaving three-eighths
of an inch depth for a wearing surface. After forty-
eight hours, or when the surface has dried, the road
is again rolled and sprinkled and then opened to traf-
fic, being meantime sprinkled daily for thirty days.

QUALITY OF SCREENINGS.

Trap. — The best "binder" for the top course, all
things considered, is probably a mixture of three parts
of trap-rock dust and screenings, with two parts of
smooth sand not too coarse. In addition to its tough-
ness, trap-rock dust has the advantage as compared
with limestone dust, of having a greater specific gravity,
so that it does not blow readily. If this mixture fails
to "bind," orif.it "ravels" afterward, a different grade
of sand may help it, or a small addition of one-fourth
or less of cementitious limestone screenings, like that
from Tompkins Cove, will certainly make it bind.

Limestone. — Some kinds of limestone screenings
make a sticky paste, which is very bad, and it is
important to select carefully and to study the effects
closely. Cementitious limestone dust and screenings
" bind " broken stone better than will any other mate-

160

QUALITIES OF SCREENINGS.

rial, and many experienced road-makers consider that
limestone of some kind is necessary to make a good
road; but the facts remain as detailed on pages 157,
158 that vast extents of perfect roads have been built
and maintained without it, both in this country and
abroad, during years past as well as recently.

Granite. — The screenings crushed from granitic rocks
and from gneiss have in some cases been successfully
used to bind the crushed rock from which they were
screened. In other cases, during 1901, perfect results
have been obtained from granite screenings which
would not " bind " by mixing with them an equal quan-
tity of carefully-chosen local sand.

Quantity of Screenings. — The actual quantity of
screenings required to thus bind the crushed stone and
to fill the voids, varies somewhat with the character
of the rock and with the degree to which it is crushed
and ground together by the roller: with trap rock,
which is not crushed by rolling, the loose yardage of
screenings needed to fill the voids will equal thirty-
three per cent of the loose yardage of the crushed rock
measured in the bin : with some gneiss, or with soft
limestone, or with sandstone, the screenings may not
exceed twenty-five per cent of the loose yardage of the
crushed stone measured in the bin. A fair average
with the various rocks will be thirty per cent, which
will be ample if the screenings are not wasted. To
this must be added whatever is required for the "wear-
ing surface."

Quantity of Water for Puddling Top Course.— The provision of water for puddling
the top course (page 160) is often an expensive matter and the quantity needed may
be varied greatly by the manner in which the work is done, being least when the
lower course has been well-filled, and greatest when the base is loose and the soil
beneath is absorbent. The quantity thus needed, on the top only, will vary from a
minimum of 15 gallons to a maximum of 48 gallons per loose cubic yard of all the
stone in both courses, averaging 28 gallons per loose cubic yard ; or two 6oo-gallon
sprinkler-tanks per 100 feet of i6-foot roadway, equaling i^i inches depth over the
whole surface.

161

MAXIMUM GRADES FOR MACADAM ROADS.

There is a wide difference between theory and prac-
tice in the matter of maximum grades on which broken-
stone roads may be built and maintained. Grades of
less than five feet per 100 feet are not only better for
the traveling public, but can also be built and main-
tained at less cost, because it is more difficult to roll
macadam on steeper grades, and because the fragments
are loosened by horses toe-calks and are washed by
rain-fall.

In the construction by state aid in the states already
named, the roads are necessarily outside of corporate
limits and are usually old highways on which the
steeper grade can be reduced by cutting the tops of the
hills and by filling the valleys, or in extreme cases by
changing the line of the road and making a new loca-
tion around a hill instead of going over its top. In
this way, the maximum grade on state work in Massa-
chusetts and in New York is nominally five feet per
hundred because this is considered to be the most
economical for the convenience of travel and for the
cost of maintenance. In both these states, grades as
steep as six and one-fourth feet per hundred are found
necessary in some cases.

102

CITY ROADS AND PAVEMENTS.

In New Jersey, among the roads built in 1900 are
the following upon which the grades are steep:

NAME OF ROAD.

Construction.

Thickness,
inches.

Width of
macadam, ft.

Max. grade,
ft. and tenths
per ioo ft.

East Passaic avenue
Budd's Lake road
Passaic ave. (E. bank
Passaic river)

Telford ....
Macadam . .

Telford

16
10 to 16

7-5
7-5

8.86

Patterson and Hamburg
Turnpike

Macadam

Mendham-Bernardville . .

Macadam ..

i°-75

Upon city streets, however, it is often difficult to
make any radical change in the grade, and always im-
possible to avoid hills by change of location, so that
grades which are steeper than these are sometimes
used, and with surprisingly good results.

The city of Newton, Massachusetts, comprises fifteen
villages in an area of twenty square miles, containing
some sixty miles of the finest macadam roads, which
are built and maintained in perfect order by commis-
sioner Chas. W. Ross, formerly member of the state
highway commission. Among these finely kept roads
are the following:

NAME.

Length of steep
grade.

Grades in
feet per ioo
feet.

VILLAGE.

STREET.

West Newton ....
West Newton ....
Newton ville . .

Chestnut street

1000 feet
i ooo feet
1000 feet
1200 feet
700 feet
600 feet
1500 feet
1000 feet

9 feet
9 feet
10 feet
10 feet
10 feet
10 feet
9 feet
12 feet

Mt. Vernon street . .
Highland avenue. . .
Otis street . .

Newtonville. . . .

West Newton ....
West Newton ....
Newton

Prospect street. . .

Putnam street

Bellevue avenue. . . .
Newtonville avenue.

Newtonville

164

STEEP GRADES FOR MACADAM ROADS.

All streets having grades steeper than five feet per
100 have paved gutters three feet or more in width for
which concrete is preferred to cobbles as being more
durable, being free from weeds, and giving the best flow.

The city of Waltham, Mass., has fine macadam streets
with the following described steep grades built since
1895:

NAME OF STREET.

Length of
steep grade.

Width of mac-
adam in ft.

Max. grade,
in feet
per ioo feet.

]VIain street

1000 feet

40 feet

Newton street

500 feet

20 feet

Plympton street

700 feet

20 feet

Bellevue street

>
400 feet

20 feet

I 2

Plympton street

400 teet

20 feet

I T.

These streets have paved gutters three and one-half
feet wide and the cost of their maintenance after the
first year is stated by superintendent R. A. Jones to be
about one cent per square yard per year.

Clinton, Mass., has the following described macadam
streets with steep grades, maintained by superintendent
Loring B. Walker:

NAME OF STREET.

Length of
steep grade.

Width of
macadam in
feet.

Max. grade,
in feet
per ioo feet.

Boy 1st on street

6000 feet

1 8 feet

Chestnut street

1800 feet

14 feet

Sterling street

3000 feet

24 feet

Church street

TOCO feet

24 feet

Main street

3000 feet

24 feet

These streets have paved gutters four feet wide.
Cambridge, Mass., has steep grades on Lancaster
street, Humbolt street and Washington avenue, main-

165

CITY ROADS AND PAVEMENTS.

tained by superintendent R. A. Brown. Medford has
a steep grade on High street while there are also steep
grades, kept in good condition, in Brookline, Chelsea,
Maiden, Winchester, Woburn and Somerville, Mass.

On Staten Island, now the Borough of Richmond of
the city of New York, there were built from 1895 to
1901, by Henry P. Morrison, M. Am. Soc. C. E., 183
miles of macadam streets, which include some having
steep grades which are described as follows : they are
now in charge of Louis L. Tribus, M. Am. Soc. C. E. :

NAME.

Width of

Max. grade

Length of

macadam in

in feet

VILLAGE.

STREET.

steep grade.

feet.

per ioo feet.

Garretson's . .

Ocean terrace. . . .

800 feet

1 6 feet

Garretson's . .

Prospect avenue. .

500 feet

1 6 feet

Stapleton. . . .

Orient avenue ....

100 feet

1 6 feet

Stapleton. . . .

Orient avenue

100 feet

1 6 feet

Garretson's . .

Four Corners' road

500 feet

1 6 feet

1 1

Stapleton. . . .

Trossack road. . . .

730 feet

1 6 feet

Clifton

Hillside avenue

1600 feet

1 6 feet

Stapleton. . . .

Occident avenue .

100 feet

1 6 feet

Stapleton ....

Occident avenue .

100 feet

1 6 feet

Stapleton. . . .

Occident avenue .

100 feet

1 6 feet

Stapleton ....

Occident avenue .

100 feet

1 6 feet

Stapleton. . . .

Louis street

300 feet

1 6 feet

Stapleton. .

Louis street. .

200 feet

1 6 feet

These streets are formed of eight inches of crushed
trap (except Trossack avenue which is six inches) all
thoroughly rolled with four inches of crown, and all
except three have paved gutters.

CONSTRUCTION OF A MACADAM ROAD.

The earth roadbed must first be drained, and in flat
streets where the usual deep side-ditches are impossible,
there must be shallow brick paved gutters to take the

1 66

SUBGRADE.

surface water at each side of the street and also porous
tile drains, two feet below them, to collect the ground
water and carry it to the sewers. See page 10.
Curbs will usually be required for a city street.

SUBGRADE.

The subgrade, must then be cleared of all soft and
loose material, preparatory to forming it on the best
grades obtainable, with a regular crown or convexity of
about one-half inch per foot for any grade up to five
per cent and for widths up to sixteen feet, and of
three-fourths inch per foot for steeper grades. (See
page 36.) Old roadbeds usually have more or less
hard and firm material beneath the objectionable dust
and mud, and this firm substratum should be dis-
turbed as little as possible by establishing the grade
line high enough to avoid it.

A steam roller passing over an earth roadbed will
disclose the existence of a surprising number of yield-
ing places and soft spots which could never be found
in any other way, but which can readily be filled, or
excavated and refilled and re-rolled, until the earth is
regular and equally hard throughout.

Instead of first forming the side-ditches and the
crowned subgrade, as is usually clone, it is sometimes
better practice and easier for the roller to grade the road-
bed flat in cross-section and at about two inches below
the desired elevation of the center of the crowned sub-
grade ; deferring the ditches until the last, unless their
excavation is at once necessary to provide grading
material or to take storm water.

On this flat roadbed, use the roller and admit traffic
until the whole surface is so hard that the wheels of a

167

CITY ROADS AND PAVEMENTS.

loaded wagon leave no ruts. When ready to prepare for
spreading stone, stake out the proposed macadam and
drive twenty-four inch by one-half inch steel pins fifty
feet apart along each edge and stretch a cord at the
correct elevation of the proposed surface of the base
course : then use square-end shovels and picks to cut
down four inches along the cords, sloping the cut to
nothing at three feet toward the center for a sixteen feet
roadway, or more for a wider one : throw the excavated
material into the center to form the crown and roll it
till firm, making the center at the right elevation and
forming the desired crown to receive the stone. The
side ditches can be left to be dug and paved after the
completion of the macadam roadway. Several expe-
rienced contractors who have doubtfully tried this
method, have adopted it as their regular practice.

All precautions must be taken to secure the per-
manence and solidity and dryness of the subgrade, and
it is an economy for the contractor during construction
to get it as hard as described because this prevents the
loss of costly crushed stone, and it is also an economy
in future maintenance by prolonging the life of the
roadway.

Broken stone roads have been " built " in cities by
spreading six inches of good crushed trap upon the
mud and dust of a soft subgrade with the result of total
failure within two years.

Sand Subgrade. — A subgrade of sand which will
not consolidate even when wet, may be fixed by cover-
ing with three inches of loam, or of shale or gravel, or
with a thin layer of broken stone, either of which will
probably consolidate under the roller after wetting.
Peculiarly loose sand is sometimes found, into which

1 68

SUBGRADE.

one's arm can be thrust to the elbow, and this has been
bound as above. This difficult condition is also well
met in an article entitled " Economic Design of Streets
and Pavements," by H. P. Gillette, M. Am. Soc. C. E.,
re-printed from the Engineering News, in the very
complete 1901 report of the highway commissioner
for New Jersey, the late Henry I. Budcl, as follows:

" Sand can be made quite as unyielding as gravel simply by filling
the voids with fine dust or pulverized sand. No rolling is
necessary. Water, if supplied in abundance, will puddle sand
to which fine dust has been supplied, until the sand becomes
hard and unyielding."

A telford base may be required as discussed on page
152. A layer, one and one-half inches thick, of three-
quarter inch to one inch broken stone, coated with hot
bitumen and rolled at once, will serve in an extreme
case where simpler ways fail.

Clay Subgrade. — Subgracles of slippery clay showing
increasing waves when rolled with a twelve ton to fif-
teen ton roller, have been consolidated, after subdrain-
ing with buried tiles, by covering the clay with a layer
of freshly-cut straw and then rolling with a lighter
roller, ten tons in weight. This has also been done by
covering the clay with a single layer of quarter inch
to half inch green brush, rolled into the moist clay
and then covered with an inch of sand and again
rolled.

Small areas or " pockets " of springy wet clay must
be removed, or must be drained and then covered with
a layer of gravel or coarse sand.

Settling a Clay Subgrade. — It is sometimes best, and
has been done with good results, to rough-grade a
clayey subgracle and to let it stand under traffic for some

169

CITY ROADS AND PAVEMENTS.

months, or better through a winter, before preparing it
to receive the broken stone.

Sandy Loam Subgrade. — This is most difficult when
the particles are very fine, so that the capillary attrac-
tion prevents sub-drains from taking the ground- water;
in such case, this part of the road must be watched
during the first wet season after completion, and if it
shows signs of yielding under traffic, the layer of broken
stone must be increased in thickness, as is discussed on
page 177, in the quotation from W. E. McClintock, M.
Am. Soc. C. E.

Various expedients must be tried until one is found,
by which the subgrade will remain firm and smooth
when the broken stone is spread and rolled upon it, so
that the fragments shall not work down into the sub-
grade, nor the material of the subgrade work up among
the fragments, under the action of the roller. The
stone thus saved is worth more than the cost of this
special work.

Remove Stones. — Stones or rocks lying within half
a foot of the top of the subgrade, and which are larger
than six inches, should be removed, lest they serve as
anvils on which traffic will crush the road-metal.

QUALITY OF ROCK TO BE BROKEN.

The rock should be hard, tough, durable and uni-
form in character, fracturing with a toothed surface and
showing a tendency to break into cubes rather than
into flakes. This latter pecularity occurs with some
rocks which would otherwise be good, and in one case
was found to be the direct result of excessive use of
dynamite in the quarry.

170

CRUSHING.

The rock should have a composition which cements
when wet and rolled, and should come clean from the

Screens and bins for screenings
and tlin;e sizes of stones.

Crusher producing 135 cubic
yds. crushed stone per day.

CRUSHING AND SCREENING ROCK.

quarry to the crusher. A softer rock may be crushed
for the base course, and its screenings will usually form
a good filler for it. (See page 161.)

CRUSHING.

The crusher should be placed where the rock will
pass down from the ledge through the crusher and
through the bins into the wagons, and then down-hill
to the work. The crusher should be set to produce
the largest size specified, and the whole product should
then be screened through a series of three revolving

171

CITY ROADS AND PAVEMENTS.

screens or cylinders pierced with circular holes, set on
a slope so that the material passes slowly as the screens
revolve into separate bins for each size. Thin slabs
and long pieces and the " tailings," should be re-crushed.
Sixty cubic yards of solid rock in the ledge allowing
for quarry waste will make about 100 cubic yards of
loose rock which will produce about 125 to 135 cubic
yards of the different sizes measured separately.

The following results were obtained in crushing hard
flinty limestone weighing 168 pounds per solid cubic
foot, or 2171 pounds per cubic yard of quarry frag-
ments of one to two cubic foot each, of which a mass
showed fifty-two per cent of voids and 100 cubic yards
produced as follows:

Size of screened Number of Weight per Per cent of

products. cubic yards. cubic foot. voids.

2 inch to \]A, inch.. ) (96 pounds 43

\Y? inch to y% inch.. j ( 91.5 pounds 45.5

^8 inch to -j^-inch.. 14 92 pounds 45.2

T3g- inch to dust inch . 19 93 pounds 44.6

One hundred and eighty cubic yards of quarry- rock
were crushed in ten hours and the product was
screened and put in bins and cars at a total cost for
plant, fuel and wages of fourteen cents per cubic yard
of product. The usual cost is twenty cents, and with
a smaller crusher, thirty cents.

The screens should be selected to produce the re-
quired sizes, two and one-half inch circular holes giving
what are known to dealers as " two inch " stone : one
and one-fourth inch holes giving " one inch," used for
the binder-coat of asphalt pavement : one inch holes
giving " three-fourths inch : " one-half inch holes giving
" screenings : " one-fourth inch holes giving " one-eighth
inch dust."

172

Finishing subgrade.

Spreading and binding foundation stone.

RIVER-ROAD NEAR BUFFALO, NEW YORK.

Surface of two inches of trap rock on base of four inches of limestone.

173

CITY ROADS AND PAVEMENTS.

The required sizes vary as indicated in the following
table showing the practice during 1901—2 in the States
named :

SIZES OF BROKEN STONE AND THICKNESS OF COURSES, IN INCHES.

LOWER COURSE
OF MACADAM.

UPPER COURSE
OF MACADAM.

SURFACE.

STATE.

Size of
Frag-
ments.

Thick-
ness
after

Size of
Frag-
ments.

Thick-
ness
after

Size of
Frag-
ments.

Thick-
ness
after

Size
not
used.

roll-

Min.

Max.

ing.

Min.

Max.

ing.

Min. Max.

ing.

New Jersey

dust %

smooth

surface'

&tol

Massachusetts.

14.

dust i Y2

smooth

surface

none.

Connecticut . . .

V/2

dust y.

Ktoi

New York

dust y.

none.

* One-half inch to one inch spread on subgrade as one-third of the hase course.

FORMATION OF LOWER COURSE.

The thickness of the layer of loose stone spread for
this course should be gauged by five and one-half inch
cubes of wood placed upon the subgrade, including a
bottom layer not more than one and one-half inches
thick of that part of the crusher product not otherwise
required.

The stone should be uniformly spread to this depth,
beginning furthest from the source of supply in order to
avoid driving over the loose stone, and using spreader-
wagons to uniformly distribute it. If ordinary wagons
are used, the stone should be shoveled from the wagons
or from the roadside. If dumped in large piles upon
the subgrade of the road, the position of each pile will
be made evident after the road is finished. When sev-
eral hundred feet of roadway have been covered, the roll-
ing should begin along each edge, lapping on to the

174

FORMATION OF TOP COURSE.

earth shoulder and rolling each side several times until
the fragments do not creep or weave before the roller
when they will be compressed to four inches. No
screenings or water should be put on till after this:
the use of dry screenings is described on page 159.

When the lower course is properly filled and bound
it will be so firm and solid that loaded wagons can pass
over it without leaving any mark, but the surface of
the stone should be free from screenings.

FORMATION OF TOP COURSE.

The top course, perferably of trap, is then spread in
the same manner, using two and three-fourths inch
gauge-blocks and rolling the loose stone to two inches,
and until the fragments do not creep and weave, before
spreading the dry screenings as described on page 160.
Sometimes it is required that the rolling of the top
course shall continue until the material is packed so
firmly that an inch cube of trap laid upon the finished
surface shall crush under the roller without sinking
into the road surface.

A properly made macadam pavement resembles a
mass of concrete, and in several cases has proved self:
supporting when the earth beneath it has been washed
out by floods, as is shown on the next page where is
given a picture of a layer of overhanging macadam
projecting two feet.

175

CITY ROADS AND PAVEMENTS.

Smooth surface of roadway.

Cave made hy washout.

J76

CROWN OR SLOPE OF MACADAM SURFACE.
THICKNESS OF BROKEN STONE FOR MACADAM ROADWAYS.

Careful studies have been made by W. E. McClin-
tock, M. Am. Soc. C. E., as to the bearing power of
various soils in order to adjust the thickness of the
layer of broken stone to suit the soil and the traffic.
His valuable conclusions are given in the 1901 report
of the Massachusetts highway commission, of which
he was Chairman, as follows :

" The Commission has estimated that non-porous soils, drained of
ground-water, at their worst will support a load of about four
pounds per square inch ; and having in mind these figures, the
thickness of the broken stone has been adjusted to the traffic.

" On a road built of fragments of broken stone, the downward pres-
sure takes a line at an angle of forty-five degrees from the hori-
zontal, and is distributed over an area equal to the square of
twice the depth of the broken stone. If a division of the load
in pounds, at any one point, by the square of twice the depth
of the stone in inches, gives a quotient of four or less, then will
the road foundation be safe at all seasons of the year. On sand
or gravel the pressure may safely be placed at twenty pounds
per square inch.

"Acting on this theory, the thickness of stone varies from four inches
to sixteen inches, the lesser thickness being placed over good
gravel or sand, the greater over heavy clay, and varying thick-
nesses on other soils. In cases where the surfacing of broken
stone exceeds six inches in thickness, the excess in the base may
be broken stone, stony gravel or ledge stone; the material used
for the excess depending entirely upon the cost, either being
equally effective."

CROWN OR SLOPE OF MACADAM SURFACE.

The convexity or crown of the roadway is usually
made one-half inch to three-fourth inch per foot each
way from the center-line for widths up to sixteen feet
and one-half inch per foot for wider city streets. (See
page 36).

177

CITY ROADS AND PAVEMENTS.

The curve must be regular so that no water can
stand upon the surface and must be continued uniformly
over the wings to the ditches or gutters at the sides so
that water will run off freely.

The roadway may have a plane surface, sloping
wholly to one side, with good results. This construc-
tion is sometimes desirable when a street-car track
occupies one side of the roadway and where it is neces-
sary to drain the surface to one side : or when car-tracks
occupy the center of the roadway and the macadam on
each side must drain wholly to the ditch on that side.
A nearly flat city street with forty feet width of mac-
adam sloping regularly one-half inch per foot from one
side to the other gave no trouble and was found in
perfect order after several years use.

COST.

The cost of broken-stone roads varies with the local
conditions and the supply of stone: the following
approximate figures are for six-inch macadam complete,
not including curbs or grading or drainage :

With local stone available, suitable for both base and
top and filler, forty-five to fifty cents per square yard.

With local stone available for base only, top and filler
coming from a distance, sixty to sixty-five cents per
square yard.

With no good local stone, all coming from a distance,
seventy to seventy-five cents per square yard.

For resurfacing roads, for which local stone is avail-
able as in Massachusetts, the average cost is ten cents
per square yard for each inch in thickness. (See page

CAUTIONS.

THINGS TO BE AVOIDED.

The work should be so planned, and the traffic so
diverted that there will be the least possible passing of
wheels over the loose stone which have been spread to
form the base course, or the top course, of a macadam
roadway. The stones should be at once rolled, and
should be bound together as soon as possible, in order
to preserve the angles and the roughly fractured sur-
faces which would be rounded and worn smooth by
traffic.

No screenings or sand, or earth from the subgrade, or
"filler" or binder of any kind, should be allowed upon
or among the regular fragments of loose stone until
they shall have been thus rolled and consolidated. It
will be difficult, if not impossible, to properly bind the
stones if any " filler " gets between the fragments while
they are loose.

Excessive rolling will injure the road, especially if
there has been too much wetting, or if the stone is
either soft or brittle. Experience is the only safe
guide.

AVERAGE COSTS OF MACADAM ROADS.*

STATE.

Year.

Aver,
depth
in
inches.

Aver,
cost
persq.
yd. in
cents.

Aver,
width
in feet.

Rate of
cost
per mile.

Details.

Connecticut

1906

6.74

79-7

15-4

$7,018

Inclu. eng'g, grad-
ing and bridges.

Massachusetts. . .

1907

84.9

7,469

Exclu. eng'g and
bridges.

New Jersey

1907

6.9

59-

13-6

4,707

Exclu. eng'g, grad-
ing and bridges.

Wash, and Ore . .

1904-7

7.6

83-9

15-7

7,707

}
Inclu. culverts

Mo. , Neb. & Kan.

1904-7

8.2

65.7

I3-I

5,123

bridges and

Illinois & Ohio. .

1904-7

9-3

74-8

I3-I

5,750

f grading.
Excluding eng'g

Fla., Ala. & Va..

1904-7

6.2

41.8

12.8

3,082

and supervis.

* From paper by M. O. Eldridge of U. S. Office of Public Roads, at the Paris
International Road Congress, October, 1908.

179

MAINTENANCE.

Broken-stone roads require constant care beginning
as soon as they are opened to traffic. The cost is less
for continuous attention than for deferred repairs.

The system of roads which was built early in this
century all over England, required then, and still con-
tinues to require, the constant attention of an army of
resident workmen living along the line of the roads and
making never-ceasing repair of ruts and breaks as soon
as they occur. Little piles of broken stone, or of stone
to be broken, were and are never-absent evidences of
constant care, and steam road rollers are often met
when driving through the country. Such care is
necessary and costly.

In London and in Paris broken-stone roads are the
roads of luxury; some of the finest streets having mac-
adamized central driveways, bordered on each side by
thirteen feet of sheet-asphalt.

In Paris the annual cost of maintenance of suburban
macadamized streets having light traffic is about one-
third the original cost of building them. In some cases
of extra heavy city traffic, the annual care costs one-
third more than the original building; that is, the
roadway fourteen inches thick has to be practically
renewed every nine months. In such cases macadam
is more costly than asphalt or wood blocks, which are
therefore replacing it.

1 80

BROKEN-STONE ROADWAY.

181

CITY ROADS AND PAVEMENTS.

The rocks available and used for broken-stone roads
in Paris are inferior to those used in and about New
York. Edward P. North, M. Am. Soc. C. E., in his
standard book, " Construction and Maintenance of
Roads," states that of the Paris broken-stone roads,
"sixty-seven per cent are made of meuliere^ twenty-three per
cent of porphyry and ten per cent of water-worn flint pebbles."
Meuliere is a qtiartzite in which coarse grains of
quartz are united by a peculiarly strong silicious cement.
Neither the meuliere, the porphyry nor the flint is equal
in durability to diabase trap.

The good condition of the Paris broken-stone roads,
in spite of their indifferent materials, is the result of
the perfect system of care which the French have
learned to give to all their roads. One of the important
avenues thus paved is the well-known driveway through
the Bois de Boulogne.

In any case, eternal vigilance and a continuing sup-
ply of money are the price of a good system of mac-
adam city roads.

Raveling. — Loosening of the surface-stone, or " rav-
eling" is the most common defect, and this is checked
and prevented by covering the traveled surface with
half an inch of coarse sand or of trap-rock or other
screenings, and by renewing this whenever it is dis-
placed by traffic, by storm-wash or by wind. This layer
prevents the toe-calks of horses from loosening the frag-
ments of stone, and retards evaporation from the binder
in which the fragments are embedded.

When the surface shows any loose fragments, these
should be promptly restored to place if possible, or
removed to one side, and the road should at once be
thoroughly wetted, sanded and rolled.

182

MAINTENANCE.

Rolling. — Rolling is of special importance in the
spring, as soon as the frost is gone and before the road-
way becomes hard and rigid; or during a soaking rain-
fall while the road is somewhat plastic : the edges
being rolled before the center, to restore and preserve
the crown. This treatment will go far to keep the road
in good condition for the rest of the year, especially if
the traveled way is then covered with half an inch of
sand or of screenings ; never with clay, ashes or loam,
unless fully mixed with three to four times their bulk
of coarse, sharp sand.

Ruts. — When short ruts appear, as they sometimes
will in the best of roads, especially during the first
spring, the top layer of stone — usually two inches thick
— should be taken out for a width a few inches more
than the rut and for its full length. This will make a
regular hole, which is slightly deeper in the middle
than at the sides, and in which the fragments of stone
should be replaced with a few additional ones of the
same sizes and kind: the larger fragments being placed
in the deeper center and the smaller ones toward the
edges.

The loose fragments must then be rammed with a
paving rammer and packed and consolidated until level
with the adjoining old surface. Screenings or sand
must then be added and brushed to fill the voids, with
a final free sprinkling to aid the binding and last ram-
ming until the patch appears as firm as the rest of the
road and the surface has been perfectly restored. A
small rut can be thus repaired by one man in a few
minutes so that the place cannot be found the next day.
Special care is necessary that the patch is made no
higher than the adjoining surface, as an elevation of

183

CITY ROADS AND PAVEMENTS.

even half an inch may cause ruts to form around the
patch. When long ruts appear, as they sometimes do
in the spring before the road has been rolled, put picks
in one roller-wheel and run it along the rut, loosening
the surface, which then level into the rut and then wet
and roll smooth.

Sometimes a rut consists of a slight depression be-
tween two slight ridges, and this condition can be
easily corrected when rain-soaked by rolling clown the
ridges with the wheels of a broad-tired wagon in which
a heavy load of stone is piled over the rear axle.

Ruts and hollows are best found and repaired during
rain, when water shows the places and helps the re-
pairs.

It was formerly considered that all repairs of the top
layer should only be made with fragments of the same
size as those which originally formed it. Experience
has shown that general and extended repairs were best
made with "three-fourths inch stone," passing a one-
inch ring. (See page 172.)

As a usual practice, the same kind of rock as formed
the original top layer should be used for its repair,
because different kinds of rock must wear unequally.
It is not well, for instance, to repair a trap-rock surface
with patches of limestone, or the reverse. A different
kind of rock may sometimes be used to good advantage
when a continuous area is to be covered, as for example
when a granitic surface has raveled and needs a two-
inch layer of " three-fourths inch " limestone, or when a
soft limestone surface has worn into ruts and needs a
similar layer of trap or of granite.

The common practice of spreading such a layer in
the ruts and upon the hard, irregular surface of an old

184

COST OF MAINTENANCE.

macadam road, leaving the loose layer for the action
of wheels, is wasteful of material and needlessly an-
noying to traffic, which should never be compelled or
allowed to pass over loose broken stone, which should
at once be packed and bound by wetting and rolling
(see page 186). When the surface becomes irregular,
or needs new stone, use a scarifier drawn by a steam-
roller to loosen the surface and break up the ruts. A
steam-roller can thus scarify perhaps 400 feet of 1 6-foot
roadway during a forenoon and can re-roll it during
the afternoon, and meantime the teeth of the scarifier
can be sharpened for the next morning's work.

Cleaning. — Mud must be scraped from the surface
of a broken-stone roadway whenever it becomes deep
enough to show tracks and to hold water. If mud is
allowed to accumulate to a general thickness of one to
two inches, and to remain, it will work down between
the fragments of stone and eventually will destroy their
bond. When this condition has been reached, resur-
facing the road will mean re-building it at a greater
cost than to have kept it clean.

Shoulders and Ditches. — These must be kept in regu-
lar form, and the washouts filled, and the ditches cleared
of sediment and dead leaves, and freed from growing
weeds and grasses.

Cost. — Definite figures for this work on city streets
are not easily kept separately, but the accounts of the
expenses of thus maintaining rural broken-stone roads
have been closely kept by the Massachusetts highway
commission for several years and are given for 166
roads with a total length of 334 miles.

Six of these roads, with a total length of seven miles,
were evidently extreme cases and are not here included.

185

CITY ROADS AND PAVEMENTS.

The remaining 160 roads, 327 miles long, ranged in
cost of maintenance from about $4 per mile to about
$300 per mile and averaged $70 per mile. The mac-
adam surface of these roads is usually fifteen feet wide,
being 8800 square yards per mile, and this at $70
equals eight-tenths of a cent per square yard per year
for maintenance: — $100 per mile is a fair allowance.

RE-SURFACING.

A trap-rock road will ordinarily endure for several
years without re-surfacing, but a limestone road will
need it much sooner, because it wears faster and blows
away more readily.

Whenever the surface of any broken-stone road
becomes worn and irregular and the lower stones are
exposed in spots, it needs re-surfacing. The street
should be treated in sections 300 or 400 feet long, or
as much as the force can begin and finish each day.
The steam-roller with picks in the wheels, (or better,
drawing a scarifier) should be run over half of this sec-
tion to loosen the top layer. If mud is found to be
mixed with the fragments of stone in the road, rakes
and potato-forks must be used to separate and save the
stones, which can be used again with the addition of
enough new stone of the same size and kind (usually
trap-rock) to restore the original thickness. If the road
has been kept properly free from mud, it will only be
necessary to acid to the loosened top a single layer of
one-inch to two-inch fragments, (or a two-inch layer of
three-fourths inch fragments) and to roll them into the
loosened top layer, until all is solid and firm, binding
with sand or with screenings, and wetting and rolling
until a wave of "grout" goes before the roller, from

1 86

COST OF MAINTENANCE.

which the picks have of course been removed. The
operations can then be repeated on the other half, and
the section opened to traffic the next day.

Cost. — This re-surfacing will require about 300 cubic
yards of loose stone and about fifty cubic yards of
screenings per mile of fifteen-foot roadway, the cost of
which will vary with the freight charges. In Massa-
chusetts, where there are no long hauls by railroad,
the cost is #700 to $880 per mile, or eight cents to ten
cents per square yard of surface for each inch of fin-
ished thickness of the broken stone.

EFFECTS OF MOTOR-CAR TRAVEL.

The foregoing comments relate to the conditions
existing up to 1906, until which time the only destruc-
tive forces were, — the feet of horses, the iron tires of
wheels and the action of wind, water and frost. Dur-
ing and since 1906, it has come to be recognized, not
only on the comparatively new road systems of Massa-
chusetts, New York, Connecticut and New Jersey and
other States, but also on the old systems of England,
France, Germany and Italy, that the vastly increasing
numbers of motor-cars are now most important factors
and that the methods of road construction and mainte-
nance which have heretofore been successful, have
failed to meet the new demands. The character of road-
surface must be bettered by using refined coal-tar or
liquid asphalt, or bitumen in some form, instead of water,
to mix with the materials, holding the stones and
binder firmly in place and preventing dust formation.

This must be done if the building of crushed stone
roads is to continue, or if existing roads are to be
preserved.

The author issued in 1908 a discussion of the sub-
ject of " Road Preservation and Dust Prevention," de-
tailing the various methods which have been used.

INDEX.

PAGE.

ABRASION TESTS — brick, 88, 89; broken stone 145, 149

ALBANY, N. Y.— asphalt, 26, 118, 120, 130; block stone, 26, 64; brick,
86, 95, 98, 130; limestone near, 141; plank roads, 67 ; railroad, first

passenger road, 20; wheel tracks, stone 19

ALEXANDRIA. LA, — brick 100

ALTON, ILL. — brick 84

ALLEGHANY, PA. — asphalt, 26; block stone, 26; brick 84, 99

ALTOONA, PA. — asphalt 56

ANCIENT PAVEMENTS 17

ANNAPOLIS, MD. — asphalt block, 128; brick 100

ASPHALT PAVEMENTS 103

American sheet asphalt —

Artificial mixture 104

Asphalt 109

Sources of 108

Base 112

Binder 112, 113

Care in building 110, 111

Cost 56, 120

Failures, causes of 124

Complete

Cracks

Disintegration by fires, gas, kerosene 126

Foundation — brick, cobbles, concrete, macadam, stone

blocks 112

Guarantee 108, 120

Materials and methods 109

Preference for, comparative 130

Proportions 110

Rolling 114

Sand.. 110, 111

Wearing surface 114

Crown 30, 118

Grades, steep 118

Block, asphalt 127

Cost 128

Extent, materials, proportions 127

Use 129

Leuba blocks 128

Companies 107

Extent of use 104

History 103

ATCHISON, KAN. — brick 84, 100

ATLANTA, GA.— asphalt, 26, 56, 118, 130; brick, 84, 95, 130; block

stone 26, 64

AURORA, ILL. — asphalt 120

BALTIMORE, MD. — asphalt, 56, 120, 130; concrete-mixer, 51 ; brick, 98 130

wood blocks 78

BELLAIRE, OHIO — brick 84

BINGHAMTON, N. Y.— asphalt, 130; brick 84, 95, 130

BIRMINGHAM, ALA. — brick 100

189

INDEX. PAGE.

BITULITHIC PAVEMENTS, 131; construction, 132, 133; cost, 134; ex-
tent, guarantee, grade, 135; opinions and results, 137; proportions,

131 ; use 136

BLOCK STONE PAVEMENTS 57

Cost 63

Defects 59

Joints, filler for 62

Kinds of rock —

Granite 57

Sandstone 61

Trap 57

Merits 61

Mileage 64

Strength 61

BLOOMINGTON, ILL. — brick 84

BOSTON, MASS. — asphalt, 26, 36, 56, 130; block stone, 26, 36, 64; brick,

130; macadam, 138; wood block 36, 65, 67, 73, 78

BRICK PAVEMENTS 82

Construction of 92, 95

Base for 92, 94

Cushion of sand 34, 92, 95

Joints, expansion 97

Fillers of joints 96

Cost of 96, 99

Paving cement, bituminous 96

Portland cement 93, 96

Sand 96

Cost of 84, 98, 100

Crown 33, 95

Curb 39

Extent 82, 85, 91, 130

Failures of 86

Fusion of material 87

Guarantee 101

Material 87

Noise 85, 96

Preference for, comparative 1 30

Qualities, hard, strong, tough 89

Reaction against use 85

Region of production 86

Rolling 93

Steep grades for 98

Success of 87

Tests-
Abrasion 88, 89

Absorption 90

Examination in use 81, 83, 90

BROCTON, MASS. — bituminous macadam 135

BROKEN STONE ROADS 138

Macadam pavements —

Binder for 156, 157

Modes of use; England, France, 157; Connecticut, New

Jersey, 158; Massachusetts, New York 159

Quality; limestone, trap, 160; granite, 161; sand,

157. 159, 161

Quantity 161

Screenings 156, 160

Cautions 1 79

Construction 166

IQO

INDP:X. PAGE.

Broken stone roads — (Continued} —

Cost 178

Courses —

Lower 174

Rolling 174, 175

Thickness 177

Top 175

Crown 36, 167, 177

Curve of 34, 178

Grades, steep 162

Gutters, paved 165

Rolling-
Courses —

Lower 174

Top 175

Excessive 179

Sub-grade 12, 167

Screenings (See Binder) 156, 160

Sprinkling 1 59, 160, 161

Sub-grade —

Clay 169

Drainage 8

Dryness 168

Loam 1 70

Sand 168

Stones in 170

Sub-drainage 10, 169

Stones —

Loose 1 79

Screenings 172

Sizes 1 74

Sub-grade 170

Water for —

Quantity. 161

Maintenance — •

Cleaning 184

Cost 1X0-185

Raveling 182

Re-surfacing 185

Cost 186

Rolling 183

Ruts 183

Scarifier 185-186

Stone for 183

Rock for roads —

Cobbles 143

Crushing 171

Flint 182

Granite 140

Limestone 141

Meuliere 182

Porphyry 140

Quality 170

Quartzite 140

Sandstone 143

Sizes 1 72, 1 74

Tests 146

INDEX. PAGE

Broken stone roads — (Continued} —

Machine for 145

Results of 148, 149

Trap 139

Uniformity 143

Sand for binder 157 159, 161

Screens 172

Systems 150

Cost, relative 153

Macadam 150

Telford 150-153

Telford pavements 150-153

Construction 151, 154, 155

Cost 153

Defects 152

Extent 154

Merits 153

Mileage 139, 156

Sizes of stones 154

BROOKLINE, MASS. — macadam 138, 166

BUFFALO, N. Y.— asphalt, 26, 36, f>(5, 104, 118, 119, 121, 130; block
stone, 26, 36, 61, 64; brick, 84, 95, 130; limestone near, 141; mac-
adam streets, 38 ; wood blocks 36

BURLINGTON, IA. — brick 84

CAMBRIDGE, MASS. — bituminous macadam, 132, 135; brick, 92, 93;

macadam 138, 165

CAR TRACKS — construction of 40

CATSKILL, N. Y. — brick 86

CEDAR RAPIDS, IA. — asphalt, 120; brick 84

CHARLESTON, S. C. — asphalt, 118; bituminous macadam 135

CHARLESTON, W VA. — brick 84

CHATTANOOGA, TENN. — asphalt 56

CHELSEA, MASS.- — macadam 165

CHICAGO, ILL. — asphalt, 28, 36; block stone, 26, 36, 64; brick, 84;

cedar block, 26, 36, 67; curbs, 39; wood blocks 68, 77

CHILLICOTHE, OHIO — asphalt block, 128; brick 99, 100

CINCINNATI, OHIO — asphalt, 26, 56, 120; block stone, 26, 64; brick. . 84
CLEVELAND, OHIO — asphalt, 56, 130; block stone, 61, 63, 64; brick, 91

130; curbs, 39; bituminous macadam 135

CLINTON, IA. — brick 84

CLINTON, MASS. — macadam 165

COBBLE PAVEMENTS 21, 57 58

COLUMBIA UNIVERSITY; tests of materials 146

COLUMBUS, OHIO— asphalt, 26, 56, 120, 130; block stone, 26, 61, 64-

brick 84, 90, 91, 95, 98, 100, 113, 118, 130

CONCRETE PAVEMENTS 64

CONCRETE 42

Aggregates 47

Base 42

Bond ". 52

Brine 54

Cement (see Hydraulic cement) 43

Results of' tests 46

Cost 55

Crusher dust 47

Freezing —

Avoid 54

Limit of cold 54

192

INDEX. PAGE,

Concrete — (Continued} —
Mixing —

Hand 48

Machine 50

Monolith 25

Plastering 53

Proportions 48

Sand _ 48

Loam in 48

Pit 48

Washing 48

Setting 53

Surface 53

Water 49

Wetting . 53

COST OF PAVEMENTS. 26, 56, 84, 100, 120, 128, 135, 153, 178

CONNELLSVILLE, PA. — brick 84

CORNELL UNIVERSITY — tests of materials 147

CORTLAND, N Y. — asphalt 120

COUNCIL BLUFFS, IA. — brick 84, 100

CROWN OF PAVEMENTS — 30; formulae for, 30, 32; form of, 34; asphalt,

33-118; brick, 33, 95; wood block, 33; macadam 36, 167, 177

CULVERTS — cast iron, 37; concrete, 37; masonry, 37; vitrified pipe. . . 37
CURBS — blue stone, 38; brick, 39; concrete, 39; cost, 40; combined, 39;
corners, 40; granite, 38; limestone, 38; sandstone, 38; setting, 38;

sizes 39

DAVENPORT, IA. — brick 84

DAYTON, OHIO— asphalt, 118, 130; brick, 84, 91, 95 130

DECATUR, ILL. — brick 84

DENVER, COL.— asphalt, 26, 36; block stone 26

DES MOINES, IA.— asphalt, 56; brick, 84, 98, 100; ced^r blocks 68

DETROIT, MICH. — asphalt, 26, 118, 130; block stone, 26; brick, 84, 91,

95, 130; cedar blocks 68

DURUQUE, IA. — brick 84

DULUTH, MINN. — cedar blocks 68

DUNKIRK, X. Y. — brick 84

DIRT ROADS — 7; rolling, 12; smooth in winter 12

DRAINAGE — 8 ; sub-drains 9, 10

ELMIRA, X. Y.— asphalt, 118, 130; brick 95, 130

ERIE, X. Y.— asphalt, 118, 130; brick 95, 98, 130

EVANSVILLE, IND. — brick 84

FALLS — of horses 36

FINDLAY, OHIO — brick 84, 100

FORT WAYNE, IND. — asphalt, 56, 118, 120, 130; brick 84, 95, 130

GALVESTON, TEX. — yellow pine blocks 68

GALESBURG, ILL. — brick 84

GARRETT, IND. — brick 100

GLENS FALLS, X. Y.— brick 97

GRAND RAPIDS, MICH. — asphalt, 118, 130; brick 95, 130

HANNIBAL, Mo. — brick 84

HARRISBURG, PA. — asphalt, 118, 130; brick 95, 130

HARTFORD, CONN. — asphalt, 118; brick 84

HARVARD UNIVERSITY — tests of materials 146

HOLYOKE, MASS. — bituminous macadam 135, 136

HOUSTON, TEX.— asphalt, 118, 120, 130; brick 95, 130

HYDRAULIC CEMENT —
Xatural — •

Use of 43, 56

193

INDEX. PAGE.

Hydraulic cement — (Continued] —

Tests of 43

Proportions 48

Portland-
Increase of 42

Proportions 48

Tests of 43

Chemical 45

Coloring; 40

Fineness 43

Hot water 44

Purity 44

Results 40

Weights 40

Use of 47

Blending 47

INDIANAPOLIS, IXD. — brick, 84; wood blocks 09, 70, 70, 77

JACKSON, MICH.— asphalt, 118, 130; brick 95, 130

JACKSONVILLE, ILL. — brick 84

JOLIET, ILL. — asphalt, 118, 120, 130; brick 95, 98, 130

JOHNS HOPKINS UNIVERSITY — tests of materials 147

KANSAS CITY, KAN.— asphalt, 20, 50; block stone, 20; cedar block. . . 20
KANSAS CITY, Mo. — asphalt, 20, 120; block stone, 20; brick, 84, 97;

cedar blocks, 20; cypress blocks 08

KEOKUK, IA. — brick 84

KENOSHA, Wis. — brick 84

KEWANEE, ILL.— brick 99, 100

KINGSTON, N. Y. — wheel tracks, stone 22, 23

LAFAYETTE, IND. — asphalt, 50; brick 84

LANCASTER, PA. — brick 84

LEXINGTON, KY. — brick 84

LINCOLN, NEB. — brick 84

LITTLE FALLS, N. Y. — granite near 141

LOCKPORT, N. Y. — brick 84

LONG ISLAND CITY, N. Y. — asphalt 123

Los ANGELES, CAL. — asphalt 50

LOUISVILLE, KY. — brick .' 84, 91

LOADS — comparative • 25

LONDON — Australian hardwood blocks 71

Macadam 180

LOWELL, MASS. — bituminous macadam 132, 135

MACADAM PAVEMENT — (See Broken Stone Roads, 138.)

MALDEN, MASS. — macadam 105

MANSFIELD, OHIO— asphalt, 118, 130; brick 95, 98, 130

MARION, OHIO— asphalt, 118, 130; brick 130

MASSILLON, OHIO — brick 84

MELBOURNE, AUSTRALIA — hardwood blocks 74

MEDFORD, MASS. — macadam 138, 100

MEMPHIS, TENN.— brick 84

MERIDEN, CONN. — asphalt, 118; brick 95

MILWAUKEE, Wis. — asphalt, 20, 50, 118, 120, 130; block stone, 20;

brick, 95, 98, 130; cedar blocks 20, 08

MINNEAPOLIS, MINN. — asphalt, 20, 130; block stone, 20, 03; brick, 130;

wood block 20, 08

MONTREAL, CANADA — asphalt, 50 ; tamarack blocks 08

MOTOR-CARS— effects of 187

MOTOR-TRUCKS — to haul crushed stone 149

MUNCIE, IND. — asphalt 118

NASHVILLE, TENN. — brick 98

NEUCHATEL, SWITZERLAND — asphalt blocks 128

194

INDEX. PAGE.

NEWARK, X. J. — asphalt 104

NEW BEDFORD, MASS. — bituminous macadam 135

NEW CUMBERLAND, W VA. — brick 87

NEW HAVEN, CONN. — asphalt, 130; brick 130

NEW ORLEANS, LA. — asphalt, 26, 36, 56, 118, 120, 130; block stone, 26,

36; brick, 95, 13Q; wood block 36

NEWPORT NEWS, VA. — asphalt 56

NEW ROCHELLE, N. Y. — wood blocks 78

NEWTON, MASS — macadam 138, 164

NEW YORK CITY, BOROUGHS OF
BROOKLYN —

Asphalt 26, 28, 36, 56, 106, 117, 126

Block stone 26, 36, 64

Cobbles 58, 116

Curbs 38

Macadam 139

BRONX —

Asphalt 107

Macadam 139

MANHATTAN —

Asphalt 26, 36, 56, 102, 104, 107, 113, 118, 121, 126

Asphalt block 127, 129

Bituminous macadam 135

Block stone 26, 36, 59, 64

Cobbles 58

Curbs 38

Macadam 139

Wood blocks 36, 61, 67, 79

QUEENS —

Macadam 139

RICHMOND —

Macadam 139, 166

NIAGARA FALLS, N. Y.— asphalt base, 55; brick 97

NORWICH, N. Y.— bituminous macadam 135

OAKLAND, CAL. — redwood blocks 68

OLEAN, N. Y.— brick 84

OMAHA, NEB.— asphalt, 26, 36, 56, 118; block stone, 26, 36; brick, 84;

cypress blocks, 68; wood block 36

OSWEGO, X. Y. — asphalt, frontispiece, 120, 126; block stone, 26; brick,

frontispiece

OTTAWA, ILL. — brick 84

OWENSBORO, KY. — asphalt 120

PARIS — asphalt, 103; concrete base, 53; macadam, 180, 181, 182; wood

blocks 70

PARKERSBURG, W. VA. — brick 98

PAWTUCKET, R. I. — bituminous macadam 135

PEORIA, ILL.— asphalt, 56, 118, 120, 130; brick 84, 95, 98

PHILADELPHIA, PA. — asphalt, 26, 33, 104, 130; block stone, 26, 36, 64;

brick, 84, 87, 98, 130; wood block 36, 67

PITTSBURG, PA. — asphalt, 26, 56, 118, 119; block stone 26

PONTIAC, MICH. — asphalt block 128

PORTLAND, ME. —asphalt, 26; block stone 26

PREFACE 5

PRESSURE — of wheels, 13; of structures 15

PROVIDENCE, R. I. — asphalt, 26, 56; block stone, 26; brick 84, 99

QTTINCY, ILL. — brick 84

RAILS— splices of, 41 ; stone 21

RICHMOND, VA. — block stone 64

ROCHESTER, N. Y. — asphalt, 26, 56, 119, 120, 130; block stone, 26, 61,

62, 64; brick, 84, 100, 130; car tracks 40, 41

195

INDEX. PAGE.

ROCKFORD, ILL. — brick 84

ROCK ISLAND, ILL. — brick 84

ROLLING 10

Dirt roads 12

ROMAN ROADS 17

Construction of 18

Cost of 18

Thickness of 16

RONDOUT, N. Y. — wheel tracks, stone. 23

ST. JOSEPH, Mo. — asphalt, 118, 130; brick 98, 100, 130

ST. Louis, Mo. — block stone, 64; brick 81, 83, 90

ST. PAUL, MINN. — asphalt, 26, 56, 118, 120, 130; block stone, 26, 63,

64; brick, 84, 95, 100, 130; cedar block, 26; curbs 39

SALEM, N. J. — Bituminous macadam 135

SALT LAKE CITY, UTAH — asphalt 118

SAN ANTONIO, TEX. — asphalt, 56, 120; mesquite blocks 68

SAND —

Cushion 34, 95

Binder for macadam roads 157, 159, 161

Filler for joints 61, 96

Strewn on pavement 28, 71, 121

For concrete 48

Washing 48

SANDUSKY, OHIO— asphalt, 118, 120, 130; brick 95, 130

SAN FRANCISCO, CAL. — asphalt, 56, 106, 118; block stone, 26; redwood

blocks 68

SCARIFIER 185, 186

SCHENECTADY, N. Y. — wheel tracks, stone 19, 22

SCHUYLERVILLE, N. Y. — trap-rock near 140

SCRANTON, PA.— asphalt, 56, 118, 130; brick 84, 95, 130

SEWERS — increased size 8

SIDNEY, N. S. W. — concrete base, 53; Australian hardwood blocks. . 71

SOMERVILLE, N. J. — macadam and telford streets 153

SOMERVILLE, MASS. — macadam streets 165

SPLICES OF RAILS — electrical, 41 ; cast iron 41

SPOKANE, WASH. — asphalt 56

SPRINGFIELD, ILL. — brick 84

SPRINGFIELD, MASS. — asphalt, 118, 130; brick, 95, 130; macadam, 138;

wood blocks 78

SPRINKLER 12

STEAM RAILROAD — first passenger railroad 20

STEAM ROLLER 11

Weight 12

Tests 12

Durability : 13

STEEP GRADES — asphalt, 27, 118; bitulithic pavement, 30, 135: block

stone, 28, 29; brick, 28, 98; broken stone, 29, 164, 166; wood block. . 29

STONE RAILS 21

STONE WHEEL-TRACKS (See Wheel-Tracks) 18

STREETS — residence, 7; width of 8

SUH-GRADE — drainage of, 9; rolling of, 42; test of 42

STEUBENVILLE, OHIO — brick 84

SUPERIOR, Wis. — cedar blocks 68

SURFACE — crown of, 30, 95, 118: reduction of, 7; ideal, 30; curve of . . 34

SYRACUSE, N. Y. — asphalt, 26, 28, 118; block stone, 26; brick 84

TAUNTON, MASS. — bituminous macadam 135

TERRE HAUTE, IND.— asphalt. 118, 130; brick, 84, 91, 95 130

TESTS— brick, 88, 89; cement, 43; stone . 145, 149

TOLEDO, OHIO— asphalt, 26, 56, 118, 120, 130; asphalt block, 1 28 : block

stone, 26, 61, 64; brick 84, 91, 98, 100, 130

196

INDEX. PAGE.

TOLLS 20, 23, 67

TOPEKA, KAN. — brick 94

TORONTO, CANADA — asphalt, 56, 118, 130; brick, 95, 130; cedar blocks, 68

TRAFFIC — pressure of 13

TROY, N. Y.— asphalt, 118, 130; block stone, 64; brick.. . . 84, 95, 98, 130

UTICA, N. Y.— asphalt, 26, 56; block stone 26

WALTHAM, MASS. — macadam 165

WASHINGTON, U. C.— asphalt, 26, 36, 56, 104, 107, 109, 130; asphalt
block, 127; block stone, 26, 36, 64; brick, 84, 130; curbs, 38; wood

block 36

WATER — quantity for puddling 161

WATERTOWN, N. Y. — brick 84

WHEELING, W. VA.— brick 84, 98

WHEEL-TRACKS, stone 18

Albany, N. Y 19

Kingston, N. Y 23

Schenectady, N, Y. 19

Cost of . . . .". 21, 24

WIDE TIRES 13

WILMINGTON, DEL. — block stone, 20; brick 84

WINCHESTER, MASS. — macadam 165

WINNIPEG — asphalt 56

WOUURN, MASS. — macadam 165

WOOD PAVEMENTS 66

American, latest types 74

Creo-resinate 78

Cost ; guarantee 80

Creosote, quantity of ; details 79

Localities 78

Pine heartwood; rosin; treatment 79

Kreodone-creosote 77

Cost; creosote, quantity of 77

Details; guarantee; localities 77

Treatment 77

American, older types —

Cedar blocks, round 20, 67

Cost; details; extent 07, 68

Cedar, Oregon, creosoted — cost 70

Cedar, Washington, creosoted — heaved 70

Corduroy roads 66

Cypress blocks 68

Mesquite blocks 08

Pine blocks — various, 70, 79; yellow (58, 79

Plank roads 00

Redwood blocks 08

Tamarack blocks 08

Australian hard woods 71

Concrete base 72

Cost < 71

Curbs; details; expansion joints 72

Life 74

Sanding 71

Crown 30, 32

Grades 28

Joints, grooved 29

Noiseless 74-79

YONKERS, N. Y. — bitulithic pavement 1 35

197

COMMENTS ON SECOND EDITION

Upon the value of the book as a text-book for students, a refer-
ence for engineers and road-builders, and a manual
for officials of cities and villages.

ENGINEERING NEWS, NEW YORK.

The local features of the first edition of this book have been omitted, and
new and later matter has been added to correspond with its title. Some
interesting historical matter on early stone wheel-tracks in America is
included, illustrated by recent views. There are also new tables for deter-
mining standard crowns, and giving the grades and costs of different kinds
of pavements and other valuable information of like character. Besides
the discussion of "Broken Stone Roads," special mention may be made of
the chapter on "Concrete Base for Pavement," which takes up cement-
tests in some detail and goes into the various phases of mixing and laying
the concrete. The illustrations include a number of fine half-tone views
of roads and pavements, both under construction and completed, many of
which were reproduced from photographs taken during the past two years.

THE NEW YORK TRIBUNE.

A Valuable Book — One of the volumes which every city engineer should
have at hand is "City Roads and Pavements Suited to Cities of Moderate
Size," by William Pierson Judson, member of the American Society of
Municipal Improvements, the American Society of Civil Engineers and
other organizations, and one of the best-known road-builders in the United
States. The work goes into the details of street construction and main-
tenance, including cost and materials, and shows a comprehensive knowl-
edge and understanding of the subject. Mr. Judson's work on the high-
ways of New York has made him well and widely known throughout this
State, and the present volume, giving the results of his experience, is of
value to every city and town where street improvement is under way or
contemplated.

MUNICIPAL JOURNAL, NEW YORK.

There have been many large and exhaustive treatises on paving and pav-
ing materials, but what has been needed is a short, concise treatise on the
present practice among cities relative to the laying of pavements, what
kinds of pavements are most favored, and how different kinds of paving
materials are wearing. "City Roads and Pavements," by William Pierson
Judson of Oswego, N. Y., treats this broad subject concisely yet liberally
enough to cover the main features.

The author is a well-known member of the American Society of Municipal
Improvements, of the American Society of Civil Engineers, and of the Eng-

COMMENTS ON SECOND EDITION.

lish Institution of Civil Engineers, and the first edition of his book, issued
in 1894, has had a wide circulation.

***********

A brief history is given of each pavement, its composition, method of
laying, cost, durability, advantages and disadvantages, etc. Mr. Judson
avoids the all-too-common practice of filling up pages with specifications
which can be secured from city engineers for the asking.

The author has incorporated some practical and simple tests for cements
that do not require the expensive apparatus and methods usually employed.
These tests, however, are entirely adequate for the purpose of detecting a
poor cement and can be made at a cost of but a few dollars. Throughout
the work tables are given which tell the practice of many cities. Cross
references show where the same subject has been treated elsewhere in the
book from a different phase.

The 186 pages form a condensation of the actual results obtained on
many works under varying conditions, and constitute a handy volume of
fine appearance, which will be of interest and value to municipal officials
and to all who are interested in road construction, and especially to stu-
dents who are preparing themselves to build roads and pavements.

Excellent illustrations are given to show the several pavements treated
and how they are laid. A full index completes the work.

THE ENGINEERING RECORD, NEW YORK.

A book in which conciseness and accuracy of statement are materially
assisted by excellent illustrations, many of unique interest, is "City Roads
and Pavements," by Mr. William Pierson Judson, M. Am. Hoc. C. E. It
is intended to supply information useful mainly in cities of moderate size,
and is wholly free from padding of any sort, which makes it a good text
book for schools as well as a practical manual for the officials of cities and
villages. The preparation of streets for pavements, the construction of
concrete foundations, and the relative merits and methods of laying stone
block, wood, brick and asphalt are fully explained. The information is
such as an engineer will find really useful, and the figures of cost of work
are fair averages. In the section on foundations, the author supplies direc-
tions for simple cement tests with an outfit costing not over $4 and giving
results which will reject no good cements but will keep out poor material.
The detailed and practical directions for making monolithic concrete in-
clude valuable features of actual good practice which are not known to be
elsewhere published. The chapters on telford and macadam road building
form by all odds the most practical and useful collection of data on the
subject with which this journal is acquainted. In the author's endeavor
to be concise, he has perhaps stated without qualification opinions on a
few disputed features of street and road work which some engineers will
question, but in such matters his views are those of most road experts
except as regards granite block pavements. His condemnation of these
is too sweeping, as they give excellent streets at a fairly low cost in parts
of the country where the blocks are prepared at local quarries.

BUFFALO EXPRESS, BUFFALO, X. Y.

Building Good Roads. — "City Roads and Pavements," by William Pier-
son Judson, has been issued in a second edition by the Engineering News
Publishing Company of New York. This book deals especially with those
varieties of hard-surfaced roads suitable for cities of moderate size, and
that includes villages. The work is of value not only to engineers and con-
tractors, but to the layman who because he is a tax-payer, a driver or an
official is, or should be, interested in this important subject.

Many commendations have been received from those who are able to
judge of its practical value. *****

COM.MKXTS OX SECOND EDITION.

BRICK, CHICAGO.

We have perused with considerable interest a very valuable book, enti-
tled "City Roads and Pavements," by William Pierson Judson, of Oswego,
N. Y., M. Am. Soc. C. E. and M. Inst. C. E. This work is devoted to a con-
sideration of city roads and pavements suited to cities of moderate size.
* * * A chapter on concrete base for pavements is of exceptional value.
Simple and ready tests are given for hydraulic cement to ascertain its fine-
ness, soundness, purity and weight, and special instructions are given for
its manner of usage, of mixing, spreading, ramming and setting. * * *
In the chapter on vitrified brick pavement, a very interesting table is given
which is a summary of reports of the modes of construction, costs and
results of brick pavements in sixty-five cities. * * * Various tests of
brick are described as also different styles of construction for ordinary and
steep grades. The work is written in a concise and lucid manner and
should have a place on the book-shelves of every student of municipal
reform. It may be secured from the publishers or from the office of
" Brick."

THE PALLADIUM, OSWEGO, X. V.

A book that should be studied by all thoughtful citizens. — "City Roads and
Pavements" is the title of a new book, by William Pierson Judson, M. Am.
Soc. Municipal Improvement; M. Am. Soc. C. E.; M. Inst. C E. * * *

Mr Judson has for years past devoted his attention largely to road-
building and pavements, and there is probably no man in the country
more competent to discuss such subjects. For that reason his book should
be read by all those, both in the city and country, who have any interest
in the improvement of public thoroughfares. In 1894 Mr. Judson issued
a book with a similar title.

In his latest book Mr. Judson goes into the details of street construction
and maintenance, and shows a thorough knowledge of the subject. Dur-
ing several years Mr. Judson's work on the highways of this State has made
him widely known.

GOOD ROADS MAGAZINE. XEW YORK.

.4 Xew Book.

* * * The best kinds of broken-stone roads, and the methods
and machines by which such roads can be built and maintained, are
described under the heading "Broken-Stone Roads," without differing
essentially from the descriptions given in the first edition. The best
pavement for a fixed steep grade in a given climate, or how steep a grade
will give good results with a given pavement, is often difficult to decide,
and tables of actual instances are given in order that engineers may know
where to find conditions similar to their own, and where they may examine
certain pavements in actual use. The sections are made to accord with
the latest records of methods and costs, and illustrations and tables are
used for the sake of brevity. * * * The statements of facts and
opinions are meant for those who wish to profit by the varied experiences
of practical road-makers. The book is clearly written, the printing is on
good paper, and the illustrations show to advantage.

ENGINEERING MAGAZINE, NEW YORK.

This is a revised and enlarged edition of a work first published in 1894.
In fact, there has been such an advance in methods of paving and road-
making in the last eight years that the present book is practically a new
one.

It contains well-illustrated and up-to-date descriptions of the various
kinds of pavements in practical use, with costs of laying and maintenance,

COMMENTS ON SKCOND EDITION.

and many statistics for cities and localities all over the United States,
with occasional reference to European experience.

There are chapters on concrete base for pavement, block-stone pave-
ment, wood pavement, vitrified brick pavement, asphalt pavement, bitu-
minous-macadam pavement and broken-stone roads.

One valuable feature is a description of simple and practical cement
tests, which can be made by the city engineer himself, with an outfit cost-
ing not over four dollars, and which can be stored in a pigeon-hole. The
book is supplied with an index, and altogether it can be heartily recom-
mended to all who are interested in city pavements.

BY EMINENT ENGINEERS AND ROAD-BUILDERS.

From BRIGADIER-GENERAL JOHN M. WILSON, Chief of Engineers, U. S.
Army, Retired, Washington, D. C. :

* * * I have just laid down the valuable book upon "City Roads
and Pavements/' and while I have not yet carefully read all its chapters, I
have been greatly interested in that upon the "Concrete .Base for Pave-
ment." The subject is handled ably, clearly and thoroughly, and in a
manner that will not only be very acceptable to the advanced engineers,
but will be most advantageous to the student who proposes to make civil
engineering his profession.

I congratulate you upon having added to the literature of our profession,
a work so replete with interesting and valuable information.

From GEORGE W. TILLSON, M. Am. Soc. C. E., Chief Engineer Bureau
Highways, Borough of Brooklyn. City of New York:

* * * The book is planned upon the right principle in showing
what is actually being done in the different cities. That is what the differ-
ent officials want to know. I see things in it, also, that are new, even
newer than my own book of two years "ago. I wish to congratulate you
on the book. * * *

From FRANK V. E. BARDOL, M. Am. Soc. C. E., Ex-Chief Engineer Dept.
Public Works, Buffalo, N. Y. :

* * * The work is a valuable addition to our scant literature on
this subject, and you are to be congratulated not only for the information
contained, but for the way in which it is presented.

From ANDREW ROSEWATER, M. Am. Soc. C. E., City Engineer of Omaha,

Nebraska :

The book is gotten up in a very compact form, and for that reason is
most convenient for ready reference of those who have occasion to inves-
tigate subjects relating to road construction.

From EDWARD P. NORTH, M. Am. Soc. C. E., New York City:

I congratulate you heartily on getting so much valuable information
into less than 200 well-printed pages. What you say of Roman roads is
the best that I have ever seen in print, covering their location, construction
and value. * * *

From HON. CHARLES W. Ross, Ex-Member State Highway Commission
of Massachusetts, West Newton, Mass. :

I think that the new edition of your book, "City Roads and Pavements,"
is just what has been needed for a long time. It seems to get right down to
facts and figures and to simplify everything in such a way that it seems
to me to be the best publication which I have seen.

It will certainly be of great value to all road builders in the country,
and it contains more valuable information on the subject, in all its branches,
than any other book of which I know.

COMMENTS ON SECOND EDITION.

From the late HON. HENRY I. BUDD, State Commissioner of Public Roads
of New Jersey, Trenton, N. J.:

I have read with great interest your valuable publication — "City Roads
and Pavements" — and find in it clearly set forth in terse terms about all
that the centuries have given us in the line of improved, roads.

It will prove an indispensable text-book for new beginners and a valu-
able assistant to those who have been some time in the traces. You have
wonderfully succeeded in describing in a few words the different materials
used, the various forms of construction, and, in fact, all the foundation
facts necessary for road improvement.

The illustrations, paper, print and general make-up of the book \vill make
it an ornament for any library.

From HON. M. O. ELDRIDGE, Assistant Director Office of Public Road
Inquiries, United States Department of Agriculture, Washington,
D. C.:

I write to congratulate you upon the revised edition of "City Roads and
Pavements," which I have just finished reading. In my judgment, it is
the best book ever written on the subject. The illustrations are well
chosen, the tables are valuable and intelligible, and your treatment of
street and road problems is concise, practical and accurate. The book's
style will appeal to the average man, and its comprehensiveness to the
road-builder and engineer. We are recommending it whenever inquiry
is made for information relating to roads and pavements.

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