Road preservation and dust prevention

City Roads and Pavements

SUITED FOR CITIES OF MODERATE SIZE

BY

WILLIAM P1ERSON JUDSON, M. Am. Soc. C. E.

Containing well illustrated and up-to-date descriptions of
the various kinds of pavements in practical use, with
costs of laying and maintenance and many statistics
for cities and localities all over the United States, and
references to European practice and experience.

THIRD EDITION, REVISED AND ENLARGED

Cloth, 6X9 inches. 197 pages. 69 illustrations.
Price, $2.00 net.

THE ENGINEERING NEWS PUBLISHING COMPANY

ROAD PRESERVATION

AND

DUST PREVENTION

BY

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 " City Roads and Pavements "

NEW YORK
The Engineering News Publishing Co.

LONDON
Archibald Constable & Co., Ltd.

1908

Copyright, 1908,

BY

THE ENGINEERING NEWS PUBLISHING COMPANY.

Entered at Stationers' Hall, London, E. C.

TABLE OF CONTENTS.

ROAD DUST— ITS CONTROL AND PREVENTION—

Origin. Limestone dust. Motor-car effects, as stated by
Institution of Civil Engineers (of Great Britain); by the U. S.
Office of Public Roads; by the Massachusetts Highway Com-
mission; by the Massachusetts Highway Association; by the
Department of Roads and Bridges of France. Need of Mainte-
nance. Conditions, and methods of prevention, in England;
in France; in the United States, (i illustration) Page 9

MOISTURE—

Water as a dust preventive. Sea-water. Calcium chloride:
origin; methods of use; details; results; cost. Akonia.
Lymanite. Fitzsimmons patent dust-layer. Conclusions:

Page i 8

OIL EMULSIONS—

Summary. Various oils used. Objections. Methods: Cook's
emulsion; Westrumite, in England, in United States, in France,
and in Germany. Westrumite 2. Pine-oiline. Coudrogenit.
Apulvite. Sandisize. Crompoid D. Dustoline. Terracolia.
Pulvicide. Ermenite. Hahnite. Rapidite. Mechanical
emulsifier. Conclusions. Page 24

OILS—

Summary. Crude petroleums: of the United States, Pennsyl-
vania, Ohio, California, Texas, Kentucky, Indian Territory;
of Russia; of Austria; of Borneo. Residual. Asphaltic.

3

265947

TABLE OF CONTENTS.

Slow distillation. Pipe line for California oil. Causes of
failures. History: first use. Oil on stone roads: at Cranston,
R. I.; at Liverpool, England; at Sidney, Australia; at Jackson,
Tenn.; at Pasadena, Cal.; at Bayonne, N. J.; at Chicago,
111.; at Beverly, Mass.; at Newton, Mass.; New York. Oiled
earth and sand roads: in California; in Eastern States. Sub-
stitutes for California asphaltic oils. Methods: petrolithic;
rolling tamper. Cheap rural oiled roads. Oiled gravel roads.
Oiled broken-stone roads. Repairs of oiled roads. Asphalt-
oilene. Asphaltine. (i illustration) Page 37

COAL-TAR PREPARATIONS—

Summary. Refined tar: Heating-kettles; uniformity. Opin-
ions: of Massachusetts Highway Commission; of Thos. Aitken,
M. I. C. E.; of French road engineers; of Logan Waller Page;
of Charles W. Ross. Methods: Success dependent upon four
conditions. Failures and their reasons. History. Tar-spray-
ing machines: competitive trials. Quality: Importance; charac-
teristics; tests; uniformity. Tarvia "A." Clare's patent Tar-
Compo. Methods: Cleaning and scraping; heating; spreading;
covering; finishing; cost. Tarvia "B," or cold treatment:
Sprinkling; cost. Tarvia on Massachusetts roads ; in parks; at
Lynn; at Wayland; at Newton. Penetration. On Rhode
Island roads: at Tiverton. Conclusions. Appliances:
" White " machine. (8 illustrations) Page 63

TAR-SPRAYING MACHINES—

"Aitken's patent pneumatic tar-sprayer": description; method;
on new macadam; cost; use on old surface; details; cost.
The "Tarspra": description; method. " Lassailly-Johnston
patent tar road-binder": description; method; results in
France and England. "Thwaite anti-road-dust machine":
description; method; cost. " Tarmaciser " : description;
method. Conclusions. Page 89

TAR-MACADAM—

Summary. Various forms. History. Hand mixing. Ma-
chine mixing. Methods in England: at Grimsby; at Notting-
ham; at Gainsborough. Tarmac: at Newark, England;

TABLE OF CONTENTS.

objections; methods; extent of use; comparative costs. Tarred
crushed stone: kinds of rock; methods; surfacing old roads;
poor method; comparative costs at seven places in England.
The " Gladwell " system : summary; methods; cost; opinions.
Tar-macadam in United States and Canada: summary;
opinion. Methods and costs: in Rhode Island; in Canada.
Comparative costs in Massachusetts; improved methods.

Page 98
ROCK-ASPHALT MACADAM.—

Summary. Sources of supply. Limitations of use. Methods :
in Little Rock, Arkansas; details; cost. In Bowling Green,
Kentucky; description of material; methods; results; cost.
Use in "Gladwell" system. Sheet rock-asphalt; methods; cost.
Binder for macadam. Page 121

BITULITHIC PAVEMENT—

Summary. Characteristics. Opinions: of George W. Tillson,
President of American Society of Municipal Improvements; of
Massachusetts Highway Commission; of Chicago South Park
Commission; expressed in the 1902 and the 1906 editions of
"City Roads and Pavements." History: growth; extent;
imitations; methods; Semiportable paving plants; descrip-
tion; views and key/ Cost. (6 illustrations) Page 127

INDEX .................. Page 137

PREFACE.

THE preservation of surface and the prevention of
dust on macadamized roads form the problem now to
be solved by engineers charged with the maintenance of
the many thousands of miles of broken-stone roads
which have been built throughout Europe during the
past century, and in certain of the United States during
the past decade.

During 1906, with the increased use of motor-cars,
this problem became acute, and in 1908 it is conceded
to be a matter of prompt betterment, or general destruc-
tion, of costly highways.

This implies that new roads proposed and in progress
must be better built than the old ones; that they must
be better bonded and surfaced; and that these results
must be reached, if possible, without unduly increasing
the cost.

Preservation of existing roads and dust prevention on
them are the matters which are most urgent, and road-
builders have been working and experimenting to these
ends with results which are here shown ; including the ob-
servations and conclusions of the writer who is indebted
for many of the details to the engineers of the works
named, as well as to the engineering publications of the
United States and of Europe, among which are : the Engi-

PREFACE.

neering News, the Engineering Record, the Good Roads
Magazine, the Municipal Journal and Engineer, and the
American Gas-light Journal, all of New York; Municipal
Engineering of Indianapolis; Engineering-Contracting
of Chicago; The Engineer, the Surveyor and Municipal
and County Engineer, and the Journal of Gas-lighting
of London; The Journal Fuer Gasbeleuchtung of Berlin;
the publications and records of the U. S. Office of Public
Roads, at Washington; the reports of the State Highway
Departments of New York, Massachusetts, New Jersey,
Connecticut, and Rhode Island; the report of the Chief
of the U. S. Corps of Engineers; the Annals des Fonts et
Chausses of France; and especially the Minutes of the
Institution of Civil Engineers of Great Britain; the
Proceedings of the American Society of Civil Engineers;
the Journal of the Massachusetts Highway Association
(as well as its informal but valuable discussions) ; and
the Proceedings of the American Society of Municipal
Improvements. The general estimate of the importance
of the subject is indicated by the extent of its discussions
in these and many other publications.

WM. P. J.

OSWEGO, New York,
July i, 1908.

8

ROAD PRESERVATION AND
DUST PREVENTION.

ROAD DUST: ITS CONTROL AND
PREVENTION.

Dust has always been a feature of broken-stone roads,
being at the same time the result of use and a check
upon excessive wear. Whenever the surface becomes
free from dust, by wind effect or otherwise, it has
been necessary to spread a thin layer of sand or screen-
ings, or other fine material, as a protection to the stone-
fragments forming the road, and to prevent them from
" ravelling" or losing their bond. When these stones
or the screenings forming the protective layer, or both,
have consisted of limestone, the resulting impalpable
dust has always been most objectionable and in
many cases has been considered intolerable, both
to people driving upon the road and especially to
those living along it. When this limestone dust is
wet, the resulting mud is the most slippery and dan-
gerous for rubber-tired wheels, causing more side-
slip than any other material used for roads.

: &OApLP£ESERVA.TION AND DUST PREVENTION,

MOTOR-CAR EFFECTS.

In 1905, when motor-cars became common, the rais-
ing and scattering of road-dust increased greatly, and
in the summer of 1906 when motor-cars became very
numerous both in Europe and in the United States,
the subject at once became acute, and road-builders
everywhere found that a new condition had suddenly de-
veloped (particularly on those macadam roads radiating
from the cities where motor-cars were most used), and
that the preservation of the roads demanded that a
better and more enduring surface be made, and one
that will neither require nor produce the loose sur-
face layer which has heretofore been a necessary
feature.

In England. — In the Minutes of Proceedings of the
Institution of Civil Engineers (of Great Britain) for
September, 1906, it is said:

"Experience has proved that the broad pneumatic tires of heavy
motor-cars at high speed draw out small particles which bind the
material of a macadamized road. On the main roads (of England)
more than half the traffic is of motor-cars, which may reasonably be
expected to become a more and more popular means of travel, to
which the roads must now be adapted by introducing into them
some material which would make them dustless; for which pur-
pose, tar, or some tar derivative, is the only remedy now in sight.
Motors have come to stay, and the road-builders mean to make
the roads fit to carry them. The estimated cost of this on the
main rural roads of England and Wales is put at eighty million
pounds and of the district roads outside the main roads at 184
million pounds. (A total of one and one-third billion dollars.)

In the United States. — That this condition equally con-
cerns the road-builders of the United States is shown in

10

ROAD DUST.

the 1907 report of Logan W. Page, Director of the
U. S. Office of Public Roads, in which he says:

"In recent years perhaps the most important and certainly the
most difficult problem which has engaged the attention of highway
engineers is the prevention of dust. Until the general introduction
of motor vehicles, dust was considered as neither more nor less
than a nuisance. The problem has now, however, assumed a more
serious aspect. The existence of our macadam roads depends
upon the retention of the road-dust formed by the wearing of the
surface. But the action of rubber-tired motor-cars moving at
high speed soon strips the macadam road of all fine material, the
result being that the road soon disintegrates. . . . This is a sub-
ject which should engage the earnest attention of the National
Government at once. No matter how important we may deem the
building of good roads, we cannot but consider it even more im-
portant to preserve those which have already been constructed."

James Owen, M. Am. Soc. C. E., one of the most
experienced of American road-engineers, in an able
paper on "Highway Construction," before the 1906
meeting of the American Society of Municipal Improve-
ments, said:

"Every system of road construction should be immediately
supplemented by a maintenance organization, for in time the con-
struction department disappears, but the maintenance department
is permanent, and is the vital point in the future road-development
of the country. . . . The automobile is demanding attention from
engineers as to whether there should not be new means and methods
for road maintenance."

At the annual meeting of the American Road-makers'
Association on March, 12, 1907. Wm. E. McClintock,
chairman of the Massachusetts Highway Commission, said :

"We have a new problem within the last six months, which is that
of the destruction of the stone road by the automobile. The surface
is denuded, the fine stone thrown off, and our commission is strug-

11

ROAD PRESERVATION AND DUST PREVENTION.

gling with the problem in the hope of finding some method to stop
the ravelling, and also to prevent the tremendous dust which follows
the motor-car."

DANGER FROM DUST.

The London Lancet of July, 1907, refers to this road-
dust as

"This great modern plague which is a menace to health."

The Paris Revue Scientifique, says:

" Street-dust is a menace to health of the gravest character, and
is a matter of life and death."

THE DUST NUISANCE

Not only does the demand for relief come from
recognized authorities and from the road-users, but
also from the property owners who live along the
roads, and pay for them, and who find that the

12

ROAD DUST.

former dust to which they had objected has become an
hundred fold worse and not to be endured; especially in
England, country residences which have long been desir-
able and valuable, have suddenly become neither tenable
nor saleable, and others have been sold for half their cost
because of the dust from adjacent roads. In Massachu-
setts, passing motor-cars have even thrown up fragments
of road-stones into the windows of houses.

CHANGE IN METHODS.

Massachusetts Highway Association. — At the meeting
of the Massachusetts Highway Association on November
12, 1907, Col. Wm. D. Sohier, of Boston and Beverly,
made the statement that

"A macadam road, made of crushed stone and bound with rolled
screenings and water, has gone out of date";

and this was not questioned by any of the hundred or
more other members present.

The situation cannot be better stated than by quoting
the 1907 report of the Massachusetts Highway Commis-
sion which has built and maintains the main parts of
one of the finest road-systems in the United States; the
Commission being seconded in every direction by the
members of the Massachusetts Highway Association,
whose local roads join and extend those of the State; the
secretary of the Commission, A. B. Fletcher, being also
the secretary of the Association, so that all road-builders
in the State profit by each other's experience and operate
in friendly rivalry; the Association thus doing for Massa-
chusetts what the American Society of Municipal Im-

13

ROAD PRESERVATION AND DUST PREVENTION.

provements aims to do for the United States and
Canada.

Massachusetts Highway Commission. — The 1907 re-
port states as follows:

"Perhaps the most important discovery of the year is the extra-
ordinarily destructive effects upon stone roads of the large number
of swiftly moving automobiles. Practically all the main roads are
thus affected. It has been noted that the binder is swept from the
road, and that the 'number-two stone' (J inch to i^ inch size) is
disturbed; in some instances standing on the surface, and in others
being left in windrows along the roadside. The Commission is
satisfied that a material change in the methods of maintaining stone
roads must be made. While old methods have proved satisfactory
in the past, they fail under the present usage. The automobile has
come to stay, and will increase in numbers, and it must be reckoned
with. It must be borne in mind that this excessive wear of stone
roads by automobiles is not confined to Massachusetts. Reports
show that the same trouble is experienced in all parts of the United
States. The roads of England, France, and other countries of
Europe are also showing signs of destruction by the same agency."

The 1908 report of the Commission says:

"The destructive work of automobiles during the past year was
even more marked than it was in 1906."

Motor-car Race-track. — The inability of good macadam
roadway to endure the effects of many motor-cars at high
speed is shown in two striking photographs made by
Cortlandt F. Bishop of Lenox and New York, whose
world-wide road-pictures are noted as being unique.
These were made in 1906 of a bend in a French broken-
stone road, first shown in perfect form and then again
two hours later when the smooth macadam surface had
been torn up into windrows of loose fragments by the
passage of an hundred racing motor-cars.

14

ROAD DUST.

EXPERIMENTAL WORK.

These conditions and opinions have led to a great
amount of experimental work, and to the invention of
many processes and devices having for their object either
temporary treatments which should hold the dust in
place, or better, the adoption of more permanent methods
which will prevent the formation of dust and which will
be applicable to the many thousands of miles of existing
fine roads of broken-stone which Europe has had for
nearly a century and parts of America for one-tenth as
long, and which must now be saved from threatened-
destruction.

In England. — The English engineers have had the
advantage of an abundant and cheap supply of
coal-tar, and have taken the lead in efforts to find
ways to get the best results from applying it, — as
well as various oil-emulsions, — to parts of their
great extent of fine and old roads. A Royal Com-
mission was appointed in 1906 to act upon the subject
of dust prevention; the authorities being moved
thereto by the wrecking of roads and the injuries to
adjacent properties all over Great Britain. In July,.
1906, an English engineer, Arthur Gladwell, of Eton,,
devised a method of using bituminous binder now
known as the " Gladwell" system, which will prob-
ably be generally used to make a fixed and dustless,
surface on macadam roads, and which is described
on page 111. Further, in May, 1907, the English Road
Improvement Association held, near Reading in Berk-
shire County, competitive trials of the various machines
and materials with instructive results, as noted at
page 70.

IS

ROAD PRESERVATION AND DUST PREVENTION.

In France. — The French engineers, whose national
road system in its general scheme and organization
and in the details of its execution and maintenance, is
the finest in the world, have devised and widely used
methods for applying bituminous binders and coatings
to road surfaces (pages 65 and 69). Because of the increas-
ingly destructive effects of motor-cars during 1906 and
1907 upon great lengths of the highways of France,
the Minister of Public Works organized an Inter-
national Congress to meet at Paris, October 11-18,
1908, under the direction of the Corps of Bridges and
Roads: The " Adaptation of Roads to Modern Traffic"
being considered and discussed in all its bearings, and
the use of coal-tar and its derivatives both in original
construction and as a surface application being given
special prominence in the program — apparently because
this material has so far given the best results on
French roads.

In the United States. — Meantime, American engineers
have produced the best form of bituminous macadam,
or bitulithic, as well as the appliances for making it
of uniform reliability and upon a large scale, and
during the past seven years have built about five
hundred miles of it in 166 cities of the United States
and Canada (page 127).

Americans have also invented a method for the con-
solidation and asphaltic treatment of sandy and other
soils, using a peculiar "rolling tamper" and heavy
asphaltic oil, and have made in California many
hundreds of miles of dustless roads which are com-
paratively cheap and which there, in the absence of
heavy rains and deep frosts, are durable. This con-
struction was extended during 1907 into Florida and

16

ROAD DUST.

Michigan, in which later the effect of frost will be
shown (see page 51).

CONCLUSIONS.

From the foregoing summary it appears that road-
engineers who wish to improve upon these various
methods which will be detailed, have ample field in which
to experiment with advantage, while those who want to
get results at once, and to check the damages by motor-
cars and the complaints by property owners, can avoid
methods which have failed elsewhere, and can use some
of those which have already been found to be more or
less successful, and which will be described.

17

MOISTURE.

WATER AS A DUST PREVENTATIVE.

The most common and the most costly way to prevent
dust and to preserve roads is to sprinkle them with
water. To keep roads always wet entails expense which
is prohibitive even for city streets and park roadways,
on some of which $700 to $900 per mile per year is
expended for sprinkling thirty to forty feet width, in
order to make them dustless during an average of six
hours per day. During dry and hot weather the
sprinkling to be effective must be repeated several
times per day and the surface alternates between mud
and dust. When tried on rural roads it has usually
been ineffective, costly, and soon abandoned.

Sea-water is used with results even more unsatisfactory,
for although the hydroscopic effect of the deposited salt
prolongs the duration of moisture on the road, its presence
in the dust and mud adds to their injurious effects; the
salty, sticky mud damaging vehicles, corroding metals,
and loosening the fragments of stone.

CALCIUM CHLORIDE.

This in solution is only to be regarded as a substitute
for water, than which it gives better effect at about the
same cost or sometimes for less.

18

MOISTURE.

Continuous moisture without frequent sprinkling
is had by dissolving in water a dequilescent salt which
is deposited in the -road and attracts moisture from
the air. Calcium chloride has, during several years
past, been extensively used for this purpose on roads
in England, where the moist climate and humid air
offer favorable conditions, and where over two hun-
dred of the local road authorities are using it increas-
ingly, its weak solution as used being non-corrosive and
harmless.

Calcium chloride (CaCJ) is a white or yellowish white,
solid, translucent, dequilescent, chemical salt, which
crystallizes in large masses and is a by-product of the
ammonia process of making bicarbonate of soda from
sodium chloride (NaCl) or common salt. It resembles
rock-salt but is harder, and has a sharp, saline taste
which burns the tongue. It dissolves completely in water
in about three hours, leaving no residue, but it evolves
heat and must be stirred to prevent caking. The cost in
England at the Northwich factory (20 miles from Liver-
pool) is 30s. ($7.25) per ton, and in the United States at
Carbondale, Pa., is $15 per ton f. o. b. cars. It is now
available in granulated form, dissolving more readily.

METHODS.

It is sometimes furnished in a forty per cent solu-
tion which is diluted as desired, using more or less water
as the character and condition of the road-material may
require. The usual practice in England is to apply
about three-fourths pound of the calcium chloride per
square yard in the first treatment of a road, and at two-
month intervals afterwards to apply about one-half as

19

ROAD PRESERVATION AND DUST PREVENTION.

much, or a total of 3 pounds per square yard per year,
costing one cent per square yard per year for the chemical.
On much exposed roads, threefold as much chemical is
applied as often as needed to keep the road moist.

The success of this treatment in the humid air of
England induced trials in the United States, and tests
were made, in September, 1906, on the macadam
and gravel roads of Beverly and Brookline in Massa-
chusetts near Boston; the results were such that the
treatment was extended during 1907 and continued in
1908.

At Beverly, Mass. — The treatment of the Beverly
road is described by Franklin C. Pillsbury, Div. Engr.
of the Mass. Highway Com., as being applied in
September, 1906, to a good macadam road, built by
the State. in 1905, part of it entirely shaded and part
open to sun and wind. As a result of the traffic of
fast motor-cars passing almost continuously (six hundred
and fifty being counted in ten hours of one Sunday),
the road surface had lost its binder and the fragments
of broken trap were exposed and beginning to ravel.
The calcium chloride was bought in dry form from the
Carbondale Chemical Co. of Carbondale, Pa., at three-
fourths cent per pound f. o. b. cars. One application
consisted in dissolving 600 pounds in 650 gallons of
water by breaking the crystals into one and one-half
inch pieces, or less, stirring for three hours; filling
the tank of an ordinary watering-cart, and sprink-
ling it over 1400 feet in length of eighteen feet road;
passing two or three times to saturate the surface. This
equalled one-quarter pound of chemical per square yard.
As a result, the dust and raveling ceased; the color was
darker because of retained moisture, but it was difficult

20

MOISTURE.

to determine connection between this moisture and the
humidity of the air as the season was not suited to obser-
vation. The application as above described was twice
repeated during 1906 and the effect was good, especially
on a portion of the road which was made of gravel.
The treatment was continued during 1907 on ten miles
of the same road, under contract calling for the chemical
treatment supplemented by sprinkling with water. Two
applications of the calcium solution were made in June,
1907, and one in each of the succeeding months to Novem-
ber 1, using one-tenth pound of calcium chloride per
square yard each time. Water was sprinkled once on
each dry day instead of four times per day as formerly.
The contract cost was $331 per mile of surface averaging
nineteen feet width, including watering as needed. The
complete treatment costing about the same as, or slightly
less than, the former sprinkling with water only. Dust
was practically eliminated.

Improved Method. — In the 1907 work the crystals
were dissolved at a "supply-station" and a saturated
forty per cent solution was used to mix with the water
in the sprinkling- tank, thus saving time and using a
patented arrangement by which an ordinary water-cart
thus equipped covers three times the area per day which
was covered by the first method. Six galvanized iron
barrels of 100 gallons capacity each are placed at hydrants
about 1000 feet apart along the road, and are each filled
with 40 per cent solution, brought in the watering-cart
from the supply-station. Each in turn is then used,
with water from the hydrant, to form 600 gallons of an
eight per cent solution in the water-cart tank, which is
then applied to 1000 feet of road. The contents of the
six barrels thus treat one mile of nineteen-feet road for

21

ROAD PRESERVATION AND DUST PREVENTION.

each trip to the supply-station at a cost for treatment of
two and one-half mills per square yard for each treatment.
The total cost for the season of the treatment and of the
watering, which together made the road dustless for five
months, was three and one-eighth cents per square yard
(or about $258 for one mile of standard 16-feet road-
way).

The same roads were similarly treated in 1908 by
the Calcide Process Company, of 402 Sears Building,
Boston, Mass.

At Brookline, Mass. — The road treated at Brookline
in 1906 is a part of Beacon Street, having a new telford
roadway where a four and one-half per cent grade
caused the many motor-cars to increase their speed to
climb the hill with destructive effect on the road. The
chemical was brought in a forty per cent solution and
was diluted to eight per cent as before described, and
was made to so saturate the surface that each particle
should be coated with the chemical and thus kept
moist, so that when dragged up by the suction of
the broad rubber tires of motor-cars running at high
speed, the damp particles should fall back onto the
road to be again bound to the surface by the next
pressure. Following English practice, a much heavier
application was made than that just described at
Beverly, with two applications in two weeks and then
once in three to five weeks, according to the weather.
The road was fully exposed to sun and wind and was
free from dust when other parts of the same road needed
sprinkling. The treatment was not continued in 1907
on this road.

22

MOISTURE.

CONCLUSIONS.

Tests have also been made elsewhere in the United
States with varying reports as to results. The climate
being less humid than in England doubtless accounts
for less success. Its obvious advantages are that it is
clean, odorless, and easy to apply, and that it is much
better than water at no greater cost.

The process is best suited to special, limited cases of
fine residence streets adjoining large cities where a
municipal supply of hydrant-water is available for sprink-
ling, and it is specially applicable as preparation for
parades or road-races. At the best, the effects of calcium
chloride are temporary and make no radical betterment
in the road surface. It is not applicable to the great
extent of existing broken-stone roads which have no
water-supply, and which demand permanent treatment
to check wear in order to reduce dust.

SOLUTIONS.

This is more or less true also of other patented solutions,
such as " Akonia" which has been used for several years
on roads in Wembley Park and Harrow, England (near
London), at a cost of about $194 per mile of sixteen feet
roadway per year, which also keeps the road damp by
attracting moisture; and "Lymanite" which is a com-
bination, by heating, of nitrate of soda, salt, and lime,
to which water is added when cold and which is then
sprinkled; and "Fitzsimmon's Patent dust-layer" con-
sisting of sand and soda fused and dissolved in water
for use.

23

OIL EMULSIONS,

SUMMARY.

These are more easily and cheaply applied than oils.
The use of emulsions avoids some of the obvious
objections to the use of oils, which many however
prefer. The effects of emulsions on road-dust are
usually only temporary, but the results are immediate
and travel is not interrupted.

There are in use many processes, patented and other-
wise, for making and applying emulsions of oil, including
vegetable oils, crude petroleum, residual oil, creosote-oil,
oil-tar, coal-tar, and similar materials, in all of which
cases some way is found to emulsify the oily or bitu-
minous material in water, so that the mixture can be
spread by a sprinkling or a spraying device, or usually
by an ordinary watering-cart. The results are more
lasting than those from the chemical salts just described.
Most of them can be applied in any weather except
during heavy rain, and there need be no interruption of
traffic.

OBJECTIONS.

Many unsuccessful attempts have been made to use
Pennsylvania and Ohio oils having a paraffin base, or
some of the Russian oils, having a naphtha base, both

24

OIL EMULSIONS.

in their crude form and in emulsions; but these have
all failed, because such petroleums are not suited to
roadwork, refusing to bind the road materials, and
having an ill odor.

Oils having an asphaltum base, like some of the petro-
leums of California, Texas, Indian Territory, Kansas,
and Kentucky in the United States, and some from
Galicia and from Baku in Europe, are the only ones
suitable; but if any kind of oil is sprayed or sprinkled in
its crude form on a hard macadam road, the result is
liable to be most objectionable in regions of normal rain-
fall, which may mix the oil into injurious mud. In any
case the greatest care must be taken to avoid getting
the oil onto objects along the roadside, and to enforce
rigid exclusion from the oiled surface for two or three
days, or until all the free oil has been absorbed or covered.
The difficulties of enforcing such precautions have led
to the use of emulsions, which soak into the ground
quickly and can be used in wet or dry weather, avoiding
time of actual rainfall.

All of these oil mixtures in which acids or alkalies are
used to form soapy emulsions which will mix with water,
may be expected to cause the subsequent road-dust (even
though it be slight in quantity) to be irritating and in-
jurious to the throat, eyes, and skin, in proportion to the
acridity of the solvent, and some of the mixtures have
been disused for that reason.

METHODS.

Boston Park Roads. — "Cook's emulsion" is an old
form, recently again used on the Boston park-roadways
in September, 1906, and consisting of 100 gallons of

25

ROAD PRESERVATION AND DUST PREVENTION.

Texas asphaltic-base residual oil, emulsified with twenty-
five pounds of coarse soap in fifty gallons of hot water.
This was mixed with cold water in such proportion that
the product contained fifteen per cent of oil and was
applied from sprinkling-wagons to the hard road-surface
which had been first covered with a thin, rolled layer
of fine screenings to absorb the oil. Two and three
distinct applications were made carefully; travel was
not interrupted; the oil did not pick-up nor spatter;
twelve miles of thirty-feet roadway so treated cost
one and one-third cents per square yard, using 1.04
pints of oil per square yard. There was no dust
during, nor after, six weeks, and the good effect con-
tinued. John A. Pettigrew, Supt. of Boston Parks,
states that the best condition was obtained when the
one-eighth inch layer of stone dust or sand was only
so saturated with oil emulsion as to be like moist brown
sugar; more oil was not desirable.

Cost. — At this rate the oiling of a sixteen-feet road-
way cost $127 per mile, and four applications per year
equaled $508 per annum per mile.

The treatment was extended during 1907 upon forty-
four miles of park roads, nearly all of which were of hard,
trap macadam. The soap used to emulsify the oil was
made from cottonseed-oil and soda and was bought solid
in barrels at four and three-fourth cents per pound. The
oil was residual Texas oil from which the naphtha, kero-
sene, and volatile parts had been distilled until the resi-
duum contained twenty-seven per cent of asphaltum, and
it was bought from the Gulf Refining Company as " road-
bed oil" at five cents per gallon in tank-cars. The emul-
sion was made by mixing eighteen pounds of soap with
fifty gallons of hot water and mixing this with 100 gallons

26

OIL EMULSIONS.

of the oil by running them through steam-pumps. The
stock thus made cost three and nine-tenth cents per gallon
and was supplied to the ordinary sprinkling- wagons, in
which water from the hydrants made the required solu-
tions of sixteen per cent of oil for the first application,
or of eight per cent or five per cent as required for the
subsequent applications, which followed at intervals of
ten days to twenty days, using a total of one and one-
half pints of oil per square yard from April 15 to
November 1, or six and one-half months, at a cost
of two cents per square yard, or $187 per mile of
sixteen-foot roadway; this included all except the cost
of sanding twice during the season ; meantime the asphal-
tum in the oil bettered the surface and less repairs were
needed. The results of this oil-emulsion treatment were
satisfactory and the dust was perfectly laid. The former
cost of watering the same roads during a similar period
had been three and one- third cents per square yard.

Conclusions. — Mr. Pettigrew considers that the use
of the residual oil itself would be better than of the
emulsion above described, but the emulsion permits
that carriages may follow immediately after the sprink-
lers, whereas oil application would necessitate closing
the roads for several days.

Chicago Park Roads. — Experimental work was done
on the park roadways of Chicago during the spring and
summer of 1907, having the primary purpose of laying
the dust, using crude and residual asphaltic oils — alone,
mixed, and in soap-emulsions of varied proportions.
The object was to find a material which would not
be sticky but would form a bond both below and
above the surface and would permit travel to be un-
interrupted and without injury. The roads were maca-

27

ROAD PRESERVATION AND DUST PREVENTION.

dam, part limestone and part granite; some bound
with limestone screenings and some with gravel. The
best results seem to have been had with a hot emulsion
of Kansas fuel-oil (being a residual oil costing three
and one-half cents per gallon from which the naphtha
and volatile parts had been distilled), California as-
phaltum, ninety-eight per cent pure, costing ten cents
per gallon, and soft naphtha soap of the "tak-a-nap"
brand, which latter mixed best with the hard lime-water
of Lake Michigan.

Mixture. — The emulsion was made by boiling sixty
gallons of water with live steam and adding fifteen
pounds of soap and boiling five minutes; adding sixty
gallons of the Kansas residual oil and pumping them
from one vat to another for five minutes to mix; then
adding twenty-five gallons (half a barrel) of California
asphaltum, ninety-eight per cent pure, and pumping
the whole for twenty minutes to emulsify the mixture,
which cost six and one-quarter cents per gallon. This
was then sprinkled upon the thoroughly cleaned and
swept surface of the hard macadam roads at the rate
of one-fifth gallon per square yard for each coating,
and five of these coats were applied in as rapid suc-
cession as possible. Meantime any small holes in the
surface were filled with sweepings from the roadside
to be cemented with the next hot emulsion application.
Roads treated in this way in Lincoln Park on June 19,
1907, remained dustless and in good order until the
middle of October, or for four months, with no other
treatment. Traffic continued during and after the
applications with no bad results, and there was no
bad odor.

Cost. — The cost of this work was excessive, being at

28

OIL EMULSIONS.

the rate of $586 per mile of sixteen-feet road for the
emulsion alone, to which was to be added the cost of
application and of patching.

WESTRUMITE.

"Westrumite" is a patented emulsion of petroleum
and ammonia, forming a sort of soap which is soluble
in water. It was invented in Germany, extensively used
there and in England (especially on stretches of road
to be used for parades or for motor-car races), and was
first brought to the United States in 1905, when it was
used experimentally on Staten Island, N. Y., and on
the Midway Plaisance in Chicago.

It is designed to suppress dust on any kind of road,
preventing soakage of water and acting somewhat as a
binder. It has a disagreeable odor for two days after
application, and makes a macadam roadway somewhat
slippery.

At Chicago. — On the Midway Plaisance the traffic was
restricted to carriages, motor-cars, and bicycles. The
roadway was of limestone macadam bound with lime-
stone screenings, and was very clean when it was first
sprinkled with westrumite on August 21 and 22, 1906.
A ten per cent solution (one part westrumite to nine
parts water) was applied from ordinary watering-carts,
0.31 and 0.175 gallon of the solution per square yard
being used for one application. At successive intervals
of about eight days the application was repeated, using
0.17 gallon (or one-sixth gallon) of a five per cent solu-
tion per square yard, the cart passing twice to make
each "application," of which ten in all were made
during eighty-three days, during which time, night and

29

ROAD PRESERVATION AND DUST PREVENTION.

day, there was no dust. The added cost to that of
using plain, free water was two and two-tenths mills
per square yard per month, or forty-five per cent more
than for free water only. This cost is based upon a
rate of seven and one-half-cents per gallon, or $20
per ton, for the westrumite, and equals $21 per month
per mile of a sixteen-feet roadway. Park superintendent
J. F. Foster considers that if the traffic had been un-
restricted and heavy, the applications needed to give
the same results would have been double the above-
named amounts applied at four-day intervals, equaling
fourfold the above cost.

In Europe. — In France, "westrumite," or some one of
several similar compounds (one known as "coudrogenit")
is much used to control dust for special occasions of
short duration, and various devices other than the com-
mon watering-cart are used. On parkways and suburban
roads where water-mains are at the roadside, water under
pressure is sometimes lead through a hose to a special
nozzle into which oil, or westrumite or other emulsion,
is fed by a branch pipe from a reservoir which is some-
times carried like a knapsack on the back of the man
holding the nozzle, or from a barrel drawn on a hand-
cart by another man. The special nozzle consists of two
conical pieces fitting together so that the water stream
acts by aspiration to draw the oil or emulsion, which
then mixes with the water in the nozzle and is spread
upon the roadway.

In Germany trials of westrumite on roads in and
near Dresden (as reported in the Minutes of the Inst. of
Civil Engineers of Great Britain for December, 1907),
gave results which were in every way satisfactory as to
prevention of dust; but the cost was four to six times

30

OIL EMULSIONS.

as great as that of ordinary watering, so that there was no
general use because of the prohibitive expense.

In the United States. — The excessive costs for the
transient results seem likely to limit the use of "west-
rumite" in the United States to special cases and to
emergencies, especially as more permanent or more
effective methods are coming into use.

In 1907, westrumite was used in a different way at
St. Paul, Minn., to saturate the layers of a granite
macadam road during its construction. A ten per cent
solution of westrumite was sprinkled on the crushed
stone before and during rolling, and a fifty per cent
solution on the limestone screenings binder, and a fifteen
per cent solution on the surface of the finished road,
aggregating about one gallon per square yard. This
treatment must have added twelve cents per square yard
to the cost of the completed road, which is said to be kept
free from dust by sprinkling with water once in ten days.

PATENTED EMULSIONS.

"Westrumite 2" is a similar ammonia emulsion of
natural bitumen, used in a somewhat similar way for the
same purposes.

"Pine-oiline" was a preparation similar to westrumite,
but its manufacture has been joined with that of the
latter.

"Apulvite" is a similar product which was used in
Geneva, Switzerland, as was westrumite; but each failed
there to give the expected results as they did not resist
rainfall.

Another patented soapy mixture is "Sandisize" formed
by mixing potash with the by-product of wool-washing

31

ROAD PRESERVATION AND DUST PREVENTION.

wastes left after extracting the major part of the grease.
It is said that the resulting emulsion does not clog the
sprayer and that it has marked hygroscopic properties.
It was originated and first used in Scotland in 1905,
where it was patented, and it is also patented in the
United States. The treatment in Scotland of one mile of
sixteen-foot roadway with ten per cent solution costs for
one application $21.50; three or four applications per
season preventing dust.

"Crempoid D" is a mixture of glue and bichromate of
potash, with oil added to soften it, and it also is applied
from a spraying-machine, or in a weak solution from a
watering-cart, and has been tried at Islington near
London, and at Bladshall in Midlothian. It was entered
in competitive tests before the English Roads Improve-
ment Association in May, 1907, and was reported to have
practically disappeared from the road in a fortnight.

Other crude oil emulsions or mixtures are the English
"Dustabato System," "Newstrand," and "Riley's Com-
pound"

"Dustoline" an American preparation made in Sum-
mit, New Jersey, is a thin, clear, yellow oil having no
"body" which can furnish any mechanical bond of the
road-material. It was used in 1907 on about five miles
of macadam roads at Newport, R. I., in two applications,
two weeks apart, without removing the layer of dust,
using from one-fourth to one-fifth gallon per square yard
for both, at a total cost for material and labor of three
and one-half cents per square yard. It costs seven and
one-half cents per gallon in car and is said to be effective
in laying dust, and to be perfectly satisfactory to the
local officials, but to have had injurious effects on rub-
ber tires and on clothing.

32

OIL EMULSIONS.

" Terracolia" is an ammonia emulsion of oil (with ten
per cent of coal-tar), and is a thick, brown, molasses-like
mixture. It was used during 1907, in five per cent and
twenty per cent solutions, in Montclair, New Jersey, and
in Prospect Park, Brooklyn, and in Bronxville, New York,
and near Boston, and is said to have given good results in
laying the dust, but at high cost.

" Pulvicide" is an English compound composed of
coal-tar creosote 50 gallons, coal-tar pitch 112 pounds,
resin 252 pounds, which are mixed and heated until
solution forms. Twenty-eight pounds of caustic soda
is then dissolved in eighteen gallons of water and poured
into the former mixture, stirring until combined. The
resulting emulsion is mixed with water, usually in the
ratio of thirty gallons to 300 gallons of water, and this
is sprinkled over the road-surface from an ordinary
watering-cart, with the result of depositing the contained
bituminous material on the surface, where it has proved
effective in laying the dust for periods of ten days, after
which another application is made. During 1906 it
was used by forty or more road authorities in England at
costs not stated. It was entered in competitive tests
before the English - Roads Improvement Association in
May, 1907, and was reported to have practically dis-
appeared in a fortnight.

"Ermenite" is an emulsion of cottonseed-oil, coal-tar,
and soap. It is formed by treating hot cottonseed-oil
with sulphuric acid, and then washing and mixing it
with four times its weight of crude tar. This mixture is
then emulsified with hot caustic soda and is then diluted
with water until it contains twenty per cent of tar. This
twenty per cent solution is mixed in the tank of an ordi-
nary watering-cart with four volumes of cold water

33

ROAD PRESERVATION AND DUST PREVENTION.

and is sprinkled on the road without mechanical stirring.
It was used during 1906 at Holmes Chapel in Cheshire,
England, at a cost not stated. When applied in the
competitive test as described, it disappeared from the
road in a week.

"Hahnite" is an emulsion formed by mixing oil and
carbolic acid heated to 150° F., with asphalt and tar,
without saponifying the oil. This is mixed with water
in an ordinary watering-cart equipped with a mechanical
stirrer actuated from the wheel-axle, and is sprayed upon
the road where it oxidizes, with the effect of laying the
dust. It has been used in England in Surrey, at Rich-
mond on the Petersham road, and by the Kingston
Corporation on the Riverside road, all suburbs of London.
In the competitive test above described, it had practically
disappeared from the road in a month.

"Rapidite" is a French compound of powdered asphalt
mixed with water, probably containing an acid or an
alkali as an emulsifier.

CONCLUSIONS.

None of these emulsions claim to be of more than
temporary effect, and in regions like the south of France
and in the French and Italian Riviera, the winter
playground of Europe, the good temporary effects
on the roads have in some cases been offset by the
injurious effects to the road-users, as stated on page 25.
In regions of heavy or frequent rainfall, the necessity
for renewal after rains has added to the cost of their use.
They do not seem to be generally adapted to American
conditions.

34

OIL EMULSIONS.

MECHANICAL EMULSIFIER.

Good results were expected from an English machine
known as the "Emulsifix" by which tar-oil or other
road-oil is mechanically emulsified in water without
the objectionable aid of acid, alkali, or heat; the
mixture being sprayed upon the road before it could
separate. This machine, having been elsewhere used,
was entered with seven others at the competitive trials
and tests before mentioned which were held by the
English Road Improvement Association near Reading
in Berkshire County on May 24-27, 1907. It then
failed to give satisfactory results, but some later modi-
fication in machine or material may supply the lack
then shown.

Method of Operation. — It consists of a horse-drawn
wagon carrying a large tank divided into two compart-
ments, one for water and the other for oil-tar or oil; a
smaller and separate tank is in the rear, in which the
oil and water meet and are there mixed by rapidly
revolving blades actuated from the wheel-axle, forming
a mechanical emulsion which is forced through a pipe in
a finely subdivided state onto and into the road-surface.
No heat is used, and valves regulate the proportions
mixed and the quantities used. Tar-oil carrying forty
per cent of tar is preferred for use in the "Emulsifix,"
and the treatment consists in applying two coats of five
per cent emulsion on two consecutive days, and afterward
at intervals of a fortnight or three weeks as required.

Results. — There is no need to close the road while the
treatment is in progress, and one wagon is said to suffice
to keep fifty or sixty miles of road in good condition

35

ROAD PRESERVATION AND DUST PREVENTION.

with eight treatments per annum, at a yearly cost of $35
to $50 per mile of twenty-four-feet road.

The machine is said to have given good results at
Knutsford, Whitington, and Chilford, all near Man-
chester; but the adverse report of the Road Improve-
ment Association judges will cause these claims to be
questioned. Such results as are claimed would be very
desirable and the device seems to have capabilities
worthy of improvement, as its success would enable the
use, at low cost, of oil emulsions free from acids.

36

OILS.

SUMMARY.

Attempts have been made since 1894 to use crude
petroleum or some of its derivatives, or some oily by-
product of gas manufacture, to control and prevent
dust. These attempts, many of them unsuccessful,
have led to knowledge as to the kinds of oil which
are unsuitable and as to the conditions which cause
failure (page 25). Experience has also shown that oils
of certain characteristics, properly applied under the
right conditions, give good results at reasonable costs.
There will undoubtedly be a great increase in the near
future in the use of heated asphaltic oils, not only to
prevent dust but also to improve sandy roads and to
preserve gravel and broken-stone roads, though there
are as yet but few examples of the latter (see page 42).

PETROLEUM.

Crude petroleums, which contain the largest proportion
of pure asphaltum, give the best results. Petroleum,
without asphaltum, having a paraffin base, like the
Pennsylvania and Ohio oils, and those having a naphtha
base, like some of the Russian oils, are useless, refusing
to bind and having ill odors and making greasy slime.
Some of the California oils as they come from the wells

37

ROAD PRESERVATION AND DUST PREVENTION.

contain so much asphaltum that they are valuable mainly
for it; some of the wells in the Bakersfield district (100
miles N.N.W. of Los Angeles), especially the "Adeline"
wells, produce petroleums having sixty to eighty-four per
cent of pure asphaltum. Such crude oils are there used
on roads with good results not otherwise equaled, by
following methods described on page 51.

Residuum. — Petroleums with asphaltic bases from the
Beaumont fields of Texas and from Kentucky, Kansas,
and Indian Territory, and some of the Russian oils from
Baku, and those from Galicia in Austria, and from
Borneo in the the far East, which are mainly valuable
for their volatile parts, leave residuum which is effective
for road work after distillation has removed the naphtha,
gasolene, illuminating-oil, and other elements which
would be detrimental for roadwork. The by-products
thus left are variously known as " residual oil," " roadbed-
oil," "fuel-oil," "steamer-oil," and other trade names.

Test. — These are usually thick, black or brown viscid
substances, whose proportion of asphaltum can easily be
determined by evaporating a weighed sample in an open,
metal pan over gentle heat until the residuum has the
hardness of commercial "D" asphalt at the standard
temperature of 60° F. The weight of this residue com-
pared with the original weight of the sample before
evaporation should show twenty-five to twenty-eight
per cent, or better, forty per cent. With less than
twenty-five per cent it is not well suited to roadwork.
Some samples so tested will show no asphaltum what-
ever, although there may have been reason to expect
to find it. Test should also be made for the amount
of contained water, which should not exceed two per
cent.

38

OILS.

Slow distillation. — It is observed that the residuum
from oil which is light in asphalt is better suited for road-
work when the distillation is done slowly, and at lower
temperature than generally used by the refiners when the
production of gasolene and illuminating-oil is the main
object, and when the ill effects of high heat on the asphal-
tum are not considered. When the distillation is done
at 300° F. instead of at 600° to 700° F., two days are
required instead of one day to do the refining; but the
resulting asphaltic residual oil is much better for road-
work, and more nearly resembles the naturally heavily
asphaltic oils of California, the contained asphaltum
showing much more of the great ductility of the Cali-
fornia asphaltum, which largely accounts for its success
in road and pavement work.

CALIFORNIA PETROLEUM SHIPMENT.

California crude petroleum, heavy in asphaltum which
is ninety-eight per cent pure, may at some future time
be available for that general use which is now prevented
by difficulties of transportation. Railroad rates across
the continent are prohibitative, and the ordinary eight-
inch pipe line which crosses at Panama and supplies fuel-
oil to the canal works has not yet been used to pass this
heavy, thick oil for road work, it having been found
in California that delivery through such a line is too
slow to be practicable even under the most favorable
circumstances. This led the Southern Pacific Railroad
to begin building, in 1907, a 282-mile specially designed
pipe line for delivering this heavy oil at Porta Costa on
an arm of San Francisco Bay. This line is an eight-inch
steel pipe rifled with six grooves making a complete turn

39

ROAD PRESERVATION AND DUST PREVENTION.

every ten feet, giving a rotary motion to the stream.
Ten per cent of water introduced with the oil is found
to be thrown by centrifugal force to the outside of the
stream of oil, where it acts as a lubricant between the oil
and the pipe, reducing friction and facilitating the pas-
sage of the oil without the need for heating it, as has
formerly been tried. The pipe line is expected to be
in operation in 1908, so that tank-ships may be able to
deliver the oil at reasonable cost at Atlantic ports.

Substitutes. — Until such time there is no reason why
the best Kentucky, Texas, or other asphaltic petroleums,
when refined by the slow process as above, should not
produce an asphaltic residual oil which will give good
results when properly used (see page 52).

FAILURES.

It has been a common thing during the past few
years for some county official, to whom all oils look
alike, to buy a car-load of oil of unknown quality
and to have it sprinkled from watering-carts in unre-
stricted quantity, without experienced direction or regard
to details of road condition or of weather, and without
attempt to remove or to cover the greasy mud caused by
sudden rainfall, or to warn the traffic to avoid the fresh
oil. The results have often been most objectionable to
residents and to road-users, and have caused opposition
and waste which good management would have avoided.
One writer says:

" The ordinary road sprinkled with petroleum is probably the most
obnoxious possible. The oil is everywhere — on plants, bushes,
trees, vehicles, and clothes."

40

OILS.

Such criticisms are based on reason, but the objectionable
features are avoidable. There have been failures from
applying oil during cool weather or upon roads not
thoroughly dry, and from the effect of rain soon after
application. Rain tends to form an emulsion with the
free oil and makes a sticky, injurious mud, and leaves
the road-surface soft (see page 15).

HISTORY.

Crude petroleum was probably first used for road work
at Santa Barbara, California, in 1894, and its use in that
State has since been general and in most cases successful.
The success has been primarily due to the peculiar
character of some of the local petroleums of which, as
stated on page 38, there are those containing forty to
eighty-four per cent of pure asphaltum, coming from the
wells as a thick, viscid, black liquid, which looks like
molasses and must be heated to give it the fluidity neces-
sary for use; some contain no asphaltum and are useless
for road work. The good results from oiling California
roads are due secondarily to the semi-arid climate, char-
acterized by dry, hot periods without rain, and to the
methods and appliances locally evolved for forming
durable, dustless roads of oiled and tamped sand or
earth, as described on pages 51, 55.

PRESERVATION OF PRESENT ROADS.

The present interest, however, attaches mainly to the
treatment of the surface of existing standard, macadam
and telford roads, formed of hard, crushed rock, located
in the central, southern, and eastern States, and in

41

ROAD PRESERVATION AND DUST PREVENTION.

Europe, where the peculiar California oil is not yet sold,
and where asphaltic residual oils like some of those from
Texas, Kansas, Kentucky, and Indian Territory for
the United States, and from Galicia in Austria, and
Baku in Russia for Europe, are the only ones available.

OIL ON STONE ROADS.

There are but few instances of such successful use,
some of which are described in order of date.

IN RHODE ISLAND.

The town of Cranston, Rhode Island, has thirty
miles of macadam roads formed of the native blue
granite, which is not quite so hard as trap, of which
granite the roads of Cranston have been built and
maintained since 1890 by P. J. Conley, highway sur-
veyor. As the town adjoins the City of Providence,
some of these roads are trunk lines subject to heavy
commercial traffic, and they are also subject to the
motor-car travel incident to such location. Since 1900
Mr. Conley, induced thereto by accounts of success
from oil treatment in California, has each year sprinkled
these roads with residual Kansas asphaltic oil (with
probably twenty-five per cent asphalt) bought from the
fuel-oil department of the Standard Oil Company at
Bayonne, New Jeresy, for four and six-tenths cents per
gallon, f.o.b. cars at Cranston.

Cost. — This has been applied cold from an ordinary
sprinkling-cart, when the roads were perfectly dry, using
about one-seventh gallon per square yard, or 1200 gal-
lons per mile of road, at a cost of $60 per mile for
each application.

42

OILS.

Results. — Two such applications have usually been
made each year. One sufficed in 1907. Dust has
been controlled. Some damage was done to motor-cars,
carriages, and clothes during the three or four days
following an application, and during and immediately
after hard rains, by the picking-up of coagulated, oily
dust; but that the results on the whole have been
satisfactory is shown by the continuance of the treat-
ment from year to year for eight consecutive years.
The cost has averaged $120 per mile per year, or
one-sixth the former cost of watering. It has without
doubt increased the life of the road, but the tenacity
of the asphalt in the oil is not sufficient to prevent
ravelling under unfavorable conditions.

IN ENGLAND.

At Liverpool, England, in 1902, and during two
years following, experiments were made on fine mac-
adam roads by applying various oils and mixtures,
hot and cold; among others was crude Texas pet-
roleum. The importance of the contained asphalt
was not then appreciated and no record was kept of
this feature. Applications were made during dry
weather only, using in 1902 an ordinary hand-water-
ing can and spreading one-eighth gallon per square
yard. Of the six materials tried, petroleum was the
least satisfactory. In 1903 it was again applied,
through hand-syringes with fine roses, using one-eighth
gallon per square yard, costing one-fourth cent, at in-
tervals of three weeks. The conclusion was that
"creosote-oil" was better, as described on page 62.

43

ROAD PRESERVATION AND DUST PREVENTION.

IN AUSTRALIA.

In 1903, at Sidney, N. S. W., Australia, macadam
roads of very hard blues tone were oiled, and the de-
tails are given by John Colin Rose, Assoc. M. Inst.
C. E., borough engineer of North Sidney. The oil
was residual, from an asphalitc American petroleum
left after the extraction of the volatile parts, and con-
sisted of part of the petroleum with vaseline and
bitumen. One-fourth gallon per square yard was
applied cold from hand-watering cans with small per-
forations, as this method was found to best avoid
excessive and unequal distribution and to be the
cheapest and most effective way. It was, however,
found necessary to shield the rails of the electric street
railway during the operation of oiling. The work
began in November (the commencement of the Aus-
tralian summer), and was confined to dry days, as it
was found that, if a heavy shower immediately followed
the oiling, the operation was wasted and that the oil
was washed into the gutters.

Cost and Results. — With labor at twenty cents per
hour and oil at six cents per gallon, the cost per
square yard was one-fourth cent for labor and one
and three-eights cents for oil, or one and six- tenths cents
total. The results were that the cementing cushion
formed by the bitumen caused the fragments of stone to
cohere, thus reducing the noise of traffic, banishing mud
and dust, increasing the life of the road, and reducing
the cost of maintenance. These results lasted after each
treatment for a minimum of two months to a maximum
of four months. In 1906 one of the roads which had

44

OILS.

been thus treated for two and one-half years remained
in first-class condition, with the binding material plastic
and much like india-rubber.

IN TENNESEE.

At Jackson, Tennessee, in 1905, the U. S. Office of
Public Roads, Logan Waller Page, Director, did some
instructive work and used a number of materials upon
macadam roads; among them were crude and residual
Texas and Louisiana oils.

Light Crude Oil. — The light, crude oil was applied
to the cleanly-swept surface of the macadam, into which
forty-eight one hundredths gallon per square yard soaked
very quickly and left no asphaltic coating on the surface.
It was first applied from a hose attached to a tank-
wagon, followed by nine men with brooms to spread
it by sweeping; this cost fifty-seven one hundredths
cent per square yard for the labor only. A street-
sprinkler operated by one man, then spread 600 gal-
lons of oil over 1200 square yards of road in fifteen
minutes, or more than twice as rapidly as the tank-
wagon and nine men. This light, crude oil produced
slight effect, and it was decided that the oil was too
volatile for the purpose and that the results did not
justify the expense of distant shipment.

Residual Oil. — The heavier medium grade of Texas
"steamer oil" was then applied hot from a street-
sprinkler, the best results being obtained at the highest
temperature. The heating must be done with steam
coils to avoid danger from fire. The force employed
consisted of a foreman and six laborers, costing $9.50
per day; one tank-wagon and one street-sprinkler,

45

ROAD PRESERVATION AND DUST PREVENTION.

costing $6 per day; two firemen, costing S3 per day;
and one ton of coal at $4; or a total of $22.50.
This applied 3300 gallons of oil per day at seven-
tenths cent per gallon for application. The cost of
the oil will vary with the locality, but at five cents
per gallon and using three-fourths gallon per square
yard, the total cost including labor equals four and one-
fourth cents per square yard. The results of applying the
Texas " steamer oil" to the macadam roads were good.
The "wearing coat" of one-eighth inch of road-dust
(which was left on the road) was saturated with the oil
and made to cohere, forming a protective coat of oil-
compacted dust which tended to prolong the life of the
road. In 1908 two and one-half years later, the city
engineer of Jackson reported that the crude oil and the
"steamer oil" had left no appreciable effects.

Heavy Residul Oil. — The heaviest residual oil, much
thicker than "steamer oil," gave the best results, and
required heating to enable it to flow, working best when
at or near boiling-point. When applied cold it formed
a thick, sticky mass, which rolled about on the road
so that its removal was necessary. When applied hot
the oil flowed freely from the tank-outlet, was spread
by hand-brooms, and was absorbed more or less into
the road, and after twenty- four hours was covered with
sand and screenings; after four days it did not show
wheel- tracks. The macadam roads thus treated with
oil were made entirely dustless, and they could be
cleaned and swept as well as the tarred roads. The
total cost, as before itemized, was about four and one-
half cents per square yard.

These results at Jackson have been widely published
and have been most useful, forming the basis for much

46

OILS.

road work in many parts of the United States. Under
date of February 25, 1908, the city engineer reported
that good results from the heavy residual oils were still
apparent after two and one-half years, the roads treated
with them being still practically dustless.

IN CALIFORNIA.

In 1906 the city o-f Pasadena, California, following
the practice which had proved successful in Riverside,
California, treated the surface of new macadam road-
ways with crude asphaltic petroleum containing eighty-
five per cent of asphaltum. Of this, one and one-fourth
to one and one-half gallons per square yard were applied
hot to the protective layer of sand which covered the
roadway, forming a thin carpet or wearing surface which
makes the macadam noiseless and dustless. The added
cost did not exceed three cents per square yard. T. D.
Allen, city engineer of Pasadena, described the work in
a paper before the annual meeting of the American
Society of Municipal Improvements.

IN RHODE ISLAND.

In 1907 the State Board of Public Roads of Rhode
Island treated the State road in the town of Barrington,
R. I., with asphaltic Texas "petroleum residuum," from
the Standard Oil Company's works at Bayonne, N. J.
One-fifth gallon per square yard was sprinkled cold
upon the road with its normal dust in place. The cost
of the oil, delivered in car, was four and six-tenths cents
per gallon; the total cost of the treatment including oil
and labor was one and one-twentieth cents per square
yard, or $103 per mile of sixteen-feet roadway. The

47

ROAD PRESERVATION AND DUST PREVENTION.

results were satisfactory (being similar to those already
described on page 42 for roads in Cranston, R. I.),
and are detailed by Asst. Engr. Arthur W. Blanchard,
Assoc. Prof, of Civ. Eng'g. at Brown University, who
gives valuable information in his paper before the Amer.
Assoc. for the Advancement of Science, with analyses of
the various oils, tars, and preparations which were used
under his direction. His opinion is further quoted at
page 84.

IN ILLINOIS.

In 1906 and 1907 part of the macadamized Sheridan
Road between Chicago and Evanston was treated with
asphaltic oil, and has since been in use by thousands of
motor-cars daily. Municipal Engineering describes the
conditions on September 16, 1906, when the roadway
was covered with motor-cars. The oiled portion was free
from dust and the blue sky was to be seen through the
clear air; while on the parts not ciled, the motor-cars
disappeared in clouds of dust which obscured the sky.
In July, 1907, the oiled portions showed the effects of
motor-car tires. The details and the cost of the treat-
ment are not given, but evidently the effects were good
but not lasting.

IN SOUTHWESTERN STATES.

In a paper before the 1906 meeting of the American
Society of Municipal Improvements, Walter F. Reichardt,
assistant city engineer of Little Rock, Ark., stated that
Texas asphaltic oil is much used, with good results, on
the macadam roads of the small cities of the Southwest,
where chert and trap from Missouri and Arkansas are

available.

48

OILS.

IN MASSACHUSETTS.

During 1907, a fifteen-feet macadam roadway in Bev-
erly, Mass., was treated with residual Texas oil containing
twenty-seven per cent of asphalt, sold by the Gulf Refining
Co. (514 Battery Park Building, New York City), as
" roadbed oil" at four and one-half cents per gallon. The
details of the treatment were described at the November
12, 1907, meeting of the Massachusetts Highway Associa-
tion in Boston, by Col. W. D. Sohier of Beverly. (See
page 13.) The broken-stone roadway being hard, dry
and well-crowned, was swept clean.

Precautions. — Between the hours of 10 A.M. and 3
P.M. of hot, dry days, heated oil was sprinkled from an
ordinary "half-moon" sprinkling-cart of which the outer
holes were plugged so as to limit the width sprinkled
to ten feet, thus avoiding spreading the oil upon the
edges of the road near the gutters. Six men preceded
and swept the road preparatory to the oiling, and two
men followed with brooms and swept and spread the oil
over the surface; part of the six men first mentioned also
scattered screened fine gravel over the fresh oil, using
one cubic yard to cover forty square yards of surface;
half a gallon of oil per square yard was thus applied
and covered at a total cost including oil of from four
to six cents, or an average of four and one-half cents per
square yard. Special care was taken to avoid oiling
damp or wet spots where the oil would only make an
oily mud; and particularly was it required that only as
much road should be oiled as could be covered and com-
pleted before night, because if rain came on the oiled
road before it was covered with fine gravel, the oil would

49

ROAD PRESERVATION AND DUST PREVENTION.

float off and form an objectionable, oily mass which must
be removed from the roadside.

OILED SCREENINGS.

At the same meeting, Charles W. Ross (see page 83),
described an effective manner in which he used the just-
described "roadbed oil" on a trap-rock macadam road
in Newton, Mass., during 1907, by mixing twenty gallons
of hot oil with one cubic yard of heated screenings until
the oil was thoroughly mixed through the mass, which
was then spread with shovels over a layer of three-fourths
inch stone, and the whole then rolled. This was done
in June, 1907, at a total cost of twelve cents per square
yard, including stone, screenings, oil, and labor. The
road was not watered during the succeeding five months,
and there was no dust, and it was satisfactory to a very
critical community. Mr. Ross further states that the oil
sprinkled over the surface of a macadam road (at a cost
of about two and one-half cents per square yard) does not
save the road from wear but merely stops the dust ; and
that a light coating of sand shaken over the freshly-
oiled surface was found to stop spattering of the oil, re-
garding which complaints were otherwise made.

IN NEW YORK.

During 1906 the State Engineer Department of New
York oiled several State roads, using crude asphaltic
Kentucky oil, known as "Raglan oil," supplied by the
Standard Oil Company at four and three-quarter cents
per gallon, delivered on car, containing thirty to thirty-five
per cent of asphalt. Five macadam roads were treated
with an average of one-fifth to one-fourth gallon of heated

50

OILS.

oil per square yard, by means of a "White" machine,
at an average cost of $128 per mile of sixteen-feet road-
way. The oiled surface was covered with one-quarter
inch of sand five hours or more after application, pre-
venting spattering of free oil. Dust was stopped for
some weeks, and the general effect seemed satisfactory.

CALIFORNIA OILED ROADS.

Summary. — Types of oiled roads peculiar to California
have been evolved from the local conditions of material
and climate, as stated on page 41. The results have
been such as to induce efforts to adapt the best of
these constructions to other conditions elsewhere.

Methods. — The best system is known as the "Petro-
lithic," and consists in mixing three and one-half to
four gallons of seventy to eighty-four per cent heated
asphaltic oil, with each square yard of surface of
loosened, moistened soil (preferably sandy and surfaced
with gravel, though even adobe clay is possible), and
consolidating with a patented " rolling tamper" into a
firm, smooth, six-inch layer, which is durable and
dustless.

Cost. — " Petrolithic " roads have been built during
several years past in thirty California cities and their
suburbs at costs varying from twenty cents to thirty-
six cents per square yard, indicating an estimated
cost of forty-five cents to fifty cents per square yard in
the Eastern States (see page 54). Oiled earth roads in
the Eastern States, similar to the " petrolithic " roads,
were advertised in 1908, by the Imperial Paving Com-
pany of New York City for the States of New York,
Connecticut, and Rhode Island, and by the Good Roads

51

ROAD PRESERVATION AND DUST PREVENTION.

Paving Company of Kansas City, Missouri, for other
States. The cost is stated to be that of good macadam,
and the method uses the "tamping roller," and binds the
soil with liquid asphalt dissolved in crude Kansas or
Texas asphalitic oil.

Oiled crushed-stone roads and gravel roads have also
been built (see page 56).

Many miles of rural earth or sand roads in California
have been treated with one gallon per square yard of
forty to seventy per cent asphaltic crude oil, some hot
and some cold, using a grader and a drag, at one-twelfth
of the above cost, or $150 per mile (see page 55).

SUBSTITUTES.

It is probable that similar results may elsewhere be
had with the residuum of other asphaltic oils, or with
coal-tar preparations like "tarvia" (page 74). It may
be, also, that commercial asphaltum derived from Cali-
fornia oil may be liquified with about forty per cent
of Texas or Kansas crude oil, so as to be like the
California oil. But nature's combinations are difficult
to imitate — it is not always possible to tell by analysis
why one oil, or tar, succeeds and another fails; and
such efforts to imitate California oils are as yet experi-
mental (see page 39).

The "White" machine for sprinkling oil is generally
used, as described on page 88.

PETROLITHIC PAVEMENT.

Methods. — The following describes the best "Petro-
lithic" pavement: The roadway is properly formed and
rolled, when dry, until solid, and all depressions are

52

OILS.

filled and tamped. The surface is then ploughed to a
depth of six inches and the loosened earth or sand thor-
oughly pulverized by repeated passages of cultivator or
harrow, and all stones of two inches diameter and larger
removed. The roadbed is then sprinkled with sufficient
water to evenly dampen the top four inches and this
depth is then worked with a lightly-set cultivator to
loosen and mix the earth and water to a uniform damp-
ness.

Oiling. — Upon this damp surface is then sprinkled
crude oil containing not less than sixty-six per cent of
soft "D" grade asphalt, nor over two per cent of
water, the oil being heated to not less than 100° F.
nor over 190° F., and being evenly spread at the rate
of one gallon per square yard of surface. This is
then thoroughly cultivated ten times, or until well
mixed to a depth of four inches. A second similar
coat of oil is then spread and turned to a depth of
four inches in the same way, until the oil and the
soil are well mixed; going over it with a cultivator at
least ten times after each coating or until every particle
of soil is coated with the oil. It is then ploughed
four inches deep with a plough that thoroughly turns
the furrows.

Tamping. — The " rolling tamper" is then applied,
beginning the tamping at six to seven inches depth
and tamping solidly upward to within two inches of the
top. The surface is then evenly covered (if gravel is
available) with two inches of hard gravel, one-quarter
inch to one and one-half inches in size, and this is
thoroughly mixed by cultivator, with the top loose two
inches of the oiled soil, using care meantime not to
disturb the tamped base. There is then spread over

53

ROAD PRESERVATION AND DUST PREVENTION.

the gravel surface one and one-half gallons of the
same hot oil per square yard, and the whole again
tamped with the rolling tamper until the entire surface
is uniformly hard and solid; an ordinary ten-ton roller
is then used to smooth the surface.

The "rolling tamper" mentioned is a peculiar and pa-
tented horse-drawn roller, manufactured and sold by
the Petrolithic Pavement Company of Los Angeles,
California, at $750 f. o. b. cars. It is about eight feet
long and five feet in diameter, weighs about 5000 pounds,
and is made in two sections for ease in turning around.
The outer surface is studded with iron legs, each pro-

ROLLING TAMPER.

jecting seven inches, the outer end of each leg being like
a sheep's foot, about two inches by three inches. There
are fifteen of these legs in each of twelve rings, or 180
in all, and they are forced into the pulverized and oiled
earth and gravel by repeated passages over the road until
it is packed to the top, so that the feet ride upon the
hardened surface. Should excess of oil then appear, suffi-
cient clean, sharp, coarse sand to absorb the oil is spread
over the oily surface, which is then rolled until solid.

Cost. — With oil costing seventy-two cents per barrel of
forty-two gallons, such roads have cost an average of

54

OILS.

twenty cents per square yard, varying up to thirty-six
cents per square yard with the conditions and cost of
oil. Such roads have been successfully built in Los
Angeles upon adobe clay, which is a most difficult
material.

OILED RURAL ROADS.

Cheaper and simpler construction has been used to
make a thousand or more miles of oiled country roads, as
described by the California State Highway Commissioner,
N. Ellery. The earth road being properly drained,
formed, crowned, and made solid, each square yard of
its surface is sprinkled with one gallon of cold crude
asphaltic oil having at least forty per cent of asphaltum,
or more, if such is obtainable; this to be determined by
tests as detailed on page 38. If it contains more than
forty per cent, heating will be necessary to give fluidity.
As soon as the oil is spread over the roadbed it is covered
at once with four inches of earth from the roadside, or
preferably with sand or fine gravel, if obtainable. It is
then compacted by rolling with an ordinary roller, horse-
drawn or steam-driven, using a grader and a drag to
keep the road-surface smooth, until the oil eventually
comes to the surface as the material packs under rolling
and use, oily spots being meantime covered with sand.
This treatment is said to be given at a cost of one and
one-half cents per square yard, or $150 per mile; but
it is evident that this figure must be increased if much
rolling is done. It requires to be followed by frequent
and careful use of the grader and drag, and many such
roads have failed for lack of this care. When well built
and maintained, the effect is to reduce the dust and

55

ROAD PRESERVATION AND DUST PREVENTION.

improve the road; but of course these cheap roads are
in no way to be compared with the " Petrolithic " roads
before described, nor with the hard gravel or stone
roads used elsewhere. If the natural earth roadbed is
of alkali soil, other soil must be spread over it, as alkali
disintegrates the asphalt in the oil.

Oiled gravel roads are also used in California, and
Commissioner Ellery describes their construction. Upon
the formed sub-grade compacted by the usual wetting
and rolling, there is spread the coarser portion of screened
gravel, four to five inches deep. This is rolled with a
ten-ton roller, and one gallon of oil having forty per
cent or more of asphalt is applied per square yard of
surface. This is at once covered with three inches of
the finer portion of the screened gravel and rolled until
compact, the oil tending to work upward into this top
layer as it packs.

Oiled broken-stone roads are similarly made, with the
usual base course of four to six inches of the one and one-
quarter inch to two and one-half inches of loose, crushed
rock, which is sprinkled with water and rolled in the
usual way. On this, when dry, there is sprinkled one
gallon of heated, heavily asphaltic oil per square yard
of surface, which is at once covered with two inches of
three-quarter inch to one and one-half inches crushed
rock over which there is spread one inch of screenings
of the same. The road is then rolled thoroughly with
a ten-ton roller until the oil shows in the screenings.
Where oil comes to the surface the spots must be
covered with more screenings. In the case of either
gravel or broken-stone roads thus oiled, the added
cost is that of the oil and its heating, less the saving
in water.

56

OILS.

REPAIRS OF OILED ROADS.

All oiled roads need close attention and prompt re-
pairs. Ruts and weaks spots must be cut out, leaving
vertical sides; the cut must then be filled with the
material of the road, — sand, or fine gravel or fine stone,
as the case may be, — mixed with oil. This added
material must be slightly higher than the surrounding
surface, after oil has been poured upon it, and it has
been thoroughly packed with a hand-tamper.

Oiled roads thus built and cared for in California have
proved to be great improvements upon their former con-
ditions, and to be comparatively dustless. The careless-
sprinkling of California asphaltic oil on unformed and
uncared-for country roads has often been tried and
found to be useless, as noted on page 39.

OILED SAND ROAD IN MASSACHUSETTS.

Methods.— In 1905 and 1906 the Massachusetts High-
way Commission oiled a common sand road in the
town of Eastham (on Cape Cod, where there is no
stone available), using a heavy Texas residual oil
containing sixty-five per cent of asphalt. Two appli-
cations, each of three-quarters gallon per square yardy
were made in 1905 and one in 1906. The oil was
heated to 180° F., and was spread from a watering-cart
with special sprinkler. Two weeks after the first coat,,
the second was applied, and the whole oiled surface was
then thoroughly chopped up with a disc harrow, rolled
with a light horse-drawn roller and then covered with
sand. Thin sprinklings of sand were added from time

57

ROAD PRESERVATION AND DUST PREVENTION.

to time to cover oil which came to the surface. The
results were generally satisfactory and the road in 1908
was in good condition after two years of use. The total
cost for the two years of treatment, exclusive of shaping,
grading, drainage, and stone, etc., was twenty- two and
one-fifth cents per square yard, or $2083 per mile of
sixteen-feet roadway. The Commission believes that
oil can be used to advantage on a road of this kind where
the roadbed is of loose sand, the drainage good, the
traffic light, and the cost of more permanent materials
is high. Frost appears to have had no ill effect upon it.

SURFACE TREATMENTS.

" Asphaltoilene" is the trade name of a prepared
residuum of Kentucky asphaltic oil, being a black, heavy
oil which looks like tar, and consists of sixty per cent
to sixty-five per cent of pure asphalt dissolved in and
carried by enough petroleum to make it fluid, thus serving
as a vehicle to deposit the contained asphalt upon the
road-surface where the petroleum is absorbed or evap-
rates.

Method and Cost. — It has probably been more used in
the Middle and Eastern States than any other one form
of residual asphaltic oil, and gives good results when
properly applied, in warm weather, to the dry surface
of clean, hard, well-drained, well-crowned, crushed-stone
roads. There is no expense for sand or screenings to
be spread over it. Asphaltoilene is prepared and used
by the Road Improvement Company of Cincinnati,
Ohio, which company contracts for the completed sur-
face at varying prices, averaging about four cents to
six cents per square yard. It is applied hot from a

58

OILS.

" White" machine, which distributes it by gravity evenly
and in regulated quantity, forming a finished surface
which is elastic, pliable, smooth, and waterproof, and
it is claimed that this surface is maintained under
heavy traffic by two applications the first year and one
each succeeding year.

Extent of Use.— During 1906 and 1907, there have
been thus treated roads in and near various cities,
among them, Louisville, Kentucky; Cincinnati, Ohio;
Detroit, Michigan; and Newton, Massachusetts. In
Detroit, the West End Boulevard was coated with
asphaltoilene in July, 1906, and has since served as
the testing speedway for ten motor-car factories, as
well as for pleasure. It is said that over 500 motor-
cars travel it every day, and at high speed, and that
its surface is dustless and good.

At Newton, Mass. — Asphaltoilene was applied to
macadam roads in Newton, Mass., in 1907, under
direction of Charles W. Ross, highway commissioner,
who considered the results very satisfactory. The heat-
ing was necessarily done by steam and not by direct
heat. When spread by a " White" machine on the road,
it looked like tar, and required several days to soak into
the road. It then was perfectly smooth and hard and
had the appearance of black india rubber. If the road
is well swept and thoroughly rolled to a smooth, hard
surface before application, the results are good. The
cost in Newton was six cents per square yard.

" Asphaltoilene " seems to closely resemble the heavily
asphaltic oils of California, and to accord with the
suggestion on page 52.

"Asphaltine" is another preparation of asphaltic
residuum, which is made in Geneva, Switzerland, where

59

ROAD PRESERVATION AND DUST PREVENTION.

it is used on macadam roads in the vicinity with good
effect. It is a mixture of the asphaltic residuum from
the petroleum of Galicia, Austria, with mazout, which
is a French by-product of petroleum refining. The mix-
ture is used hot or cold, but the former gives the best
results. The average cost in Geneva is about three
cents per square yard, including labor of heating and
spreading.

OILS DERIVED FROM GAS MANUFACTURE.

Summary.— "Oil-tar," "tar-oil," "oil- gas -tar," "water-
gas-tar" are several names for a substance much used
on English roads (and known as "odocreol" in France
and Italy), which is a by-product of the manufacture
of carburetted water-gas (used to enrich coal-gas) from
the asphaltic residuum of Russian petroleum, known as
"solar-oil" or other similar residuums.

"Creosote-oil" is a distillate from the coal-tar which
is condensed during distillation of coal-gas from bitu-
minous coal.

COMPOSITION.

Substances known commercially by each of these
names vary as widely in composition and character as
do the materials from which they are derived, and espe-
cially as the treatments of these materials vary. It is
sometimes difficult because of these variations to account
for success or failure in their use on roads.

"Oil-gas-tar" one of its several names, is a brown-
black liquid having the odor and appearance of coal-
tar, except that its greater fluidity permits its distribu-

60

i t

OILS.

tion from a sprinkler, without heating. Its specific
gravity is about 1.04. Its composition is about as follows
(see table on page 86):

Light oils, volatile from 70° F. to 170° F 11.2 per cent

Medium " " " 170 " " 230 " 22

Heavyoils, " " 230 " " 260 " 16

Anthracene, ' ' above 260 ' ' ' * 42

Water, 3 per cent; loss, 5.8 per cent; 8.8

100. o

METHODS.

It may be applied cold, as it is exceptionally penetrating
and abates dust well, but it requires several coats to give
results. It is most effective when applied hot; in either
case the road-surface must be thoroughly cleaned and
put in good condition. It has usually been applied from
hand-sprinklers, repeating the coating until the surface
is filled. The protective asphaltic skin which quickly
forms, prevents dust and is not much affected by light
traffic which need not be interrupted during application,
nor by rain which may come soon after it has soaked into
the road, which it does quickly. But it does not endure
heavy traffic and it does not resist heavy rains. Its
advantages over coal-tar are that it can be applied more
quickly, without interruption of traffic, and at less cost,
which has been about one cent for the first coat and less
for following coats, of which two or more may be required
to constitute one application. Its duration is not great
under traffic, and it can only be considered as being one
of the best of the dust palliatives, and it has been ex-
tensively so used both in England and in France.

61

ROAD PRESERVATION AND DUST PREVENTION.

CREOSOTE-OIL.

"Creosote-oil" distilled from coal-tar, resembles coal-
tar somewhat in appearance and has a characteristic
objectionable odor. Mixed with resin, and mixed with
tallow, and also alone, it was used on Liverpool roads in
competitive tests in 1902 and 1903, and was then consid-
ered to give better results than any others of a number
of dust preventatives which were tried (page 43). One-
eighth gallon per square yard was applied with hand-
watering cans and with syringes. Time was required
for its absorption, and therefore one-half of the width
of the road was treated at a time, so that rubber-tired
vehicles could meantime use the other half. The con-
clusion of the tests was that creosote-oil was cheapest
and most enduring. The dust was laid by it, and
there was marked reduction in the wear of the mac-
adam road-surface as shown by the reduced sweepings.

CONCLUSION.

Further experience has shown the greater durability
and efficiency of refined coal-tar in preference to this
derivative.

62

COAL-TAR PREPARATIONS.

SUMMARY.

Refined coal-tar, produced in gas manufacture and
treated to remove its injurious parts and yet to preserve
its ductility and to secure uniformity, has been generally
accepted by the road authorities of France and England ,
and also by those road-engineers in the United States
who have given the subject most attention, as being the
material with which to improve broken-stone roads;
binding the surface of existing roads and bettering the
construction of new roads, thereby preventing the
formation of road dust.

HEATING.

In the several following descriptions of heated tar
applications, the desirable degree of heat is mentioned
in each case, but in actual practice it is most difficult to
regulate this closely. Even when thermometers are put
into the tar to test it, there is no means of knowing the
temperature at the bottom of the kettle where it may
vary quickly, especially when a wood fire is used for the
heating. In many cases where road-tarring has failed,
this is no doubt a result of thus overheating the tar.

63

ROAD PRESERVATION AND DUST PREVENTION.

Kettles. — In some of the 1906 experimental work of
road-tarring in New York, the wheeled tar-kettles were
of seventy-five gallons capacity each, and a continuous
supply of hot tar was secured by keeping a barrel of tar,
or tarvia, emptying into the kettle at about the same
rate that the hot tar ran from it onto the road.

In the 1907 Massachusetts work at Westwood, Wayland,
and Weston, the kettles used were of five-hundred gallons
capacity each, giving better protection from over-heating.
They had wood-burning grates covering the entire kettle
bottom, and also arrangements to have two barrels, and
sometimes three barrels of tar emptying into the kettle
while the hot tar ran out; but this latter feature was not
much used. For suggested improvements, see page 119.

Steam-coils. — In any case where direct fire is used to
heat the tar, there is danger of overheating and of the
consequent failure of the work. To avoid this steam-
heated coils should be used when possible.

UNIFORMITY.

For success in such use of tar, its quality is most im-
portant (see page 71). If it is heated too much and
"refined" too far, it becomes brittle and makes black
dust. If not refined enough, the light oils and ammo-
niacal liquors will disintegrate it. A reliably uniform
product is essential. This requirement is supplied by
" tarvia" in the United States and by "Clare's patent
tar compo" in England, and doubtless by others.

Good tar, properly applied, is the cheapest and best
lorm of dust-preventer and road-saver, being more
effective and durable than any other now known.

64

COAL-TAR PREPARATIONS.

OPINIONS.

Massachusetts. — In accord with this is the statement
of Division Engineer Franklin C. Pillsbury, of the
Massachusetts Highway Commission, made to the
November, 1907, meeting of the Massachusetts High-
way Association that,—

" The Commission concludes that, for the present, tarviating (or
treating with prepared coal-tar) is the best method now known for
protecting the surface of macadam roads,"

This decision was reached after a year of use and
observation of results on Massachusetts roads.

England. — This also accords with the opinion, in
August, 1907, of Thomas Aitken, M. Inst. C. E., a
recognized English authority on road-construction and
author of " Road-making and Maintenance," who
says :

"There can be no doubt that the building-up of the road-stone
coating with a matrix of refined tar, chips and dust as a binding
medium, is the best possible method of solving the dust problem in
a satisfactory and permanent manner. " (This refers to the results
of forcing a fine spray of coal-tar into the road-material, rather than
spreading the tar over the surface and trusting to absorption.)
See page 89.

France. — French road-engineers also express the same
opinions in the Annales des Fonts et Chausses after
four years of experience in tarring broken-stone roads
under their charge. M. Heude, chief engineer of the
department of the Seine and Marne, and M. Sigault,
M. Girardeau, M. Arnaud, and M. Vahheur, city engi-
neer of Paris, all substantially agree that tarring has
been shown to be a practical means of preventing

65

ROAD PRESERVATION AND DUST PREVENTION.

dust in summer and mud in winter, and that the
saving exceeds the cost, and that future new roads
will be tarred. The general acceptance in France of
these opinions is further evidenced by the announce-
ment that "the use of coal-tar and its derivatives will
be given special prominence in the programme" of
the International Road Congress, organized by the
French Minister of Public Works, to meet in Paris in
October, 1908 (see page 16).

United States. — Logan Waller Page, Director of the
United States Office of Public Roads at Washington,
D. C., states on April 20, 1908, regarding an application
of crude tar, in August, 1905, that the results after
two and one-half years are still good on portions of
the roads, and on the whole have been satisfactory,
the roads so treated being still noticeable for the
absence of mud and dust. This refers to work
done by the office at Jackson, Tennessee, where
an old macadam road (of non-absorbent novaculite
crushed rock), on the main business street, was treated
with crude coal-tar from Alabama coke, at the rate of
forty-five one-hundredths gallon per square yard. The
tar was heated to 160° to 190° F., and was applied
through a flatted, one-inch nozzle, and spread with
brooms, during hot, dry weather.

Other opinions are given in connection with following
descriptions of actual works.

66

COAL-TAR PREPARATIONS.

CONDITIONS.

Success depends upon—

The quality of the tar, which must be the best possible ;

The state of the weather, which must be clear and
warm;

The condition of the road-surface, which must be
clean and dry;

The manner of application, which must be rapid and
complete.

OBJECTIONS.

Too much tar on the surface will be worse than the
former mud and dust, being sticky when warm and
slimy when wet. These objections are avoided when
the tar, either cold or hot, is forced in a fine spray into
the minute voids and spaces between the stone fragments,
by means of pneumatic pressure from a " tar-sprayer,"
by which the quantity and the distribution are made
uniform, and small pools of tar are not left on the
surface.

TAR- SPRAYING.

Such a tar-sprayer must work so rapidly that full
advantage can be taken of warm, dry weather, during
which to treat one-half of the width of several miles
of road per day.

Four kinds of such machines are made and used in
England and one or more in France, as described on
pages 69 and 89.

The application of tar by forcing a fine spray into the
body of the road is too recent to predict the endurance

67

ROAD PRESERVATION AND DUST PREVENTION.

of a broken-stone road so treated; but the most con-
servative opinion of road-builders experienced in this
work is that such roads will last at least twice as long
as formerly, and that meantime there will be a con-
siderable annual saving in the decreased cleaning and
repairing. At the least, this means less cost and less
dust.

FAILURES.

There have been many failures in using tar on
roads, both in original construction and in surface
treatment, or "painting." Some have been caused by
the poor quality of the tar as detailed on page 7 1 . Some
have resulted from careless methods, some from ex-
cessive traffic, and some from unexplained causes.

In New York. — One conspicuous piece of road which
was treated with tarvia in 1906 was more or less a
failure, because no attempt seemed to have been made
to dry damp spots in shaded portions nor to put the
road in proper condition before application.

In Massachusetts. — Another case is in the city of
Springfield, Mass., where half a mile cf macadam
roadway, on a four and one-half per cent grade, was
tarviated in 1906. It is stated by Arthur A. Adams,
superintendent of streets, that the tar, which had
apparently been properly applied, had entirely disap-
peared within a year, under heavy traffic.

There are no doubt other failures, but the general
opinion of users is favorable. One disadvantage of
tar-painting with crude tar, is that a road recently so
treated sometimes has a coat of black, slimy mud,
when frost and snow are succeeded by continuous
rain; and such mud is difficult to remove.

68

COAL-TAR PREPARATIONS.
HISTORY.

The use of coal-tar in the original building of
broken-stone roads is no new thing, it having been so
used in Nottingham, England, in 1840, and more or
less throughout England and France for thirty years or
more; and also in the United States. But its application
to the surface of an existing macadam road was first
made in France at Sainte-Foy-la-Grande, near Bordeaux,
unsuccessfully, in 1880; and next at Melbourne, Australia,
in 1886, where the macadam was first put in good,
firm condition, and refined coal-tar was then spread upon
it, and was covered with screenings of crushed stone.
The results were so good that the method has since
been continued there.

It was next used for this purpose byM. Girardeau,
of Fontenay-le-Comte, road commissioner of the depart-
ment of the Vendee in France, in 1896, on the State road
from Lucon to Pointe de 1'Aiguille. The results led to
other tests in various parts of the great national road
system of France, and in 1898 it was discovered that by
applying the tar hot, it then better penetrated the road
(being thus made thin like water), and that it cemented
the road dust between the fragments of stone, which
thus were held in a plastic but firm matrix.

TAR-SPRAYING MACHINES.

The tar treatment of road surfaces was then adopted
in England, and inventors there and in France devised
various machines for increasing the speed and decreas-
ing the cost of application, which were mainly accom-
plished by forcing the tar, either cold or hot, by pneumatic
pressure through spraying-nozzles, giving rapid and

69

ROAD PRESERVATION AND DUST PREVENTION.

uniform flow and distribution without the need of hand-
sweepers. Those machines which are able to spray tar
which is cold, thereby avoid the considerable expense
and trouble of heating it. The heat is so quickly lost
that it is of little effect after the tar is spread.

TESTS.

A competitive trial of these machines was held by
the English Roads Improvement Association, acting
with the Motor Union and the Royal Automobile Club,
May 22 to 27, 1907, at Reading, in Berkshire County,
England, where there were present road-engineers and
representatives of motor-car associations from all parts
of Great Britain, as well as from France, Germany,
Italy, and Egypt. Eight machines and thirteen mate-
rials were tested by actual use, though the roads and
weather were not dry enough for best results. Six
months later, when the results of the work were
known, the judges awarded two prizes, and made
mention, in the order named:

First: — "Aitkens Pneumatic Tar-sprayer," two

sizes, hot or cold tar under pressure.
Second: — "Tarspra," three sizes, hot or cold tar

under pressure.

Third:— " Johnston-Lassailly Patent Tar road-
binder," hot tar by gravity, spread by automatic

trailing brushes.
Fourth: — "Thwaite anti-road dust system," hot

tar under pressure.
Fifth: — "Tarmaciser," steam traction-engine to

clean road; heat and apply tar and cover and roll.

Each of these is described on pages 89-97.

70

COAL-TAR PREPARATIONS.

The three first named are each very effective, having
done much good work in England or France, or both.
It is said in London that their best features may yet
be combined in one machine. None are yet used in
the United States, where distribution is still made by
slow gravity flow, usually requiring that the tar be
heated and be spread by hand-brooms, at high cost for
labor, and at a rate of progress about one-twentieth of
that at which better work is done in Europe.

COAL-TAR QUALITY.

It has come to be recognized since 1905 that " coal-
tar" is a very indefinite term, and that the products
of different gas-works vary widely with the kinds
of coal used and the methods of treatment, each of
which is frequently changed, even at the same gas
works. This knowledge has led to careful tests and
analyses of different types of coal-tar to determine, if
possible, why some succeeded and others failed in road
work. This induced treatment by experts to remove
objectionable components and those which would be
soluble in rain-water, and to add desirable ones which
might increase fluidity or add to the permanence of
ductility and adhesiveness, which should be such that
after boiling, the coal-tar may be drawn out in long
threads. Many failures which had formerly occurred
were explained by the former omission of such tests
and absence of such qualities. It is recognized that
most road engineers lack the time and equipment to
analyze each lot of tar, or to interpret the results of
such tests, which are at best costly and uncertain and
are of little general utility with the present knowledge of
the subject.

71

ROAD PRESERVATION AND DUST PREVENTION.

There can be no successful system of tarring road
unless there is available a uniform standard and a reliable
supply of refined tar. The lack of these in England
accounts for many failures, and has so far prevented the
universal use which would be expected from knowing
of the many successes.

SPREADING TARVIA FROM A SLOTTED SPRINKLER (Pittsburg, Pa.).

VARIATIONS.

Every city has its gas-works,— often several of
them, — each using various grades cf coal, and fre-
quently changing their methods of treatment to make
gas. Even when these features are constant, the
quality of crude tar from a given supply-tank will
vary as the quantity in the tank varies, the tar drawn
from the bottom of a full tank sometimes differing
materially from that drawn when the same tank is
nearly empty. The resulting crude coal-tars are there-

72

COAL-TAR PREPARATIONS.

fore produced in great variety, so that road-construc-
tion which succeeds at one time may fail at another.
Most failures have resulted from using poor tar.

UNIFORMITY.

The need for uniformity is met in the United States
by a prepared refined coal-tar, widely known as
"Tarvia," which has been used and commended by
the United States Office of Public Roads at Wash-
ington, and by the Massachusetts Highway Commis-
sion (page 65), and by many city and road engieners
throughout the United States and Canada, where one
million square yards were tarviated during 1906 and
three millions in 1907. It is supplied and guaranteed
by the manufacturers, the Barrett Manufacturing Com-
pany, of 17 Battery Place, New York City. It is also
used in England where it is specified for the "Glad-
well" system (see page 112).

In Great Britain, a similar place seems to be filled by
"Clare's Patent Tar Compo," of Stanhope Street, Liver-
pool, to which was awarded the first prize at the com-
petitive tests described on page 70, at which there were
entered twelve other preparations. The tests then were
not conclusive as to the others, as the roads were not as
dry as they should have been. But the judges were
satisfied as to the good qualities of the one named, and
the road treated with it showed best results after five
months, due in great measure to its extreme fluidity,
which gave considerable penetration even when applied
cold as advised by its makers. It also had body
enough to hold together the small dust-forming par-
ticles. The odor was unobjectionable. One-seventh

73

ROAD PRESERVATION AND DUST PREVENTION.

gallon per square yard was applied in two coats, costing
for the material a little over one cent per square yard.

CONDITIONS.

The same conditions of season, climate, and road
apply to both of these materials, except that in England
and France the cost of application is less and the rapidity

PRELIMINARY SWEEPING IN PREPARATION FOR TARVIA (Jackson, Term.).

is greater, because of the improved pneumatic machines
there used for spreading.

TARVIA.

Preparations. — A road to be treated with this, or
with any tar, should be of well-built, firmly bonded
broken-stone in fairly smooth condition. If it is newly

74

COAL-TAR PREPARATIONS.

SPREADING BY HOSE FROM TANK. (Michigan Boulevard, Chicago).

THE FINAL ROLLING. (Pittsburg, Pa.).
TARVIATING.

75

ROAD PRESERVATION AND DUST PREVENTION.

built it should have been opened to traffic and thor-
oughly dried out before preparing to tar it. Then the
surface should be swept or scraped until the fragments
forming the wearing surface are exposed.

If it is an old road, such thorough cleaning is specially
important in order to remove any caked screenings which
may have been left on the surface to protect it, or any
foreign matters which may be there. If not removed
before the tarvia is spread, they will afterward dry out
and become loose and break the tarviated surface.

HOT TARVIA TREATMENT.

When the firmly-bonded macadam is thoroughly
cleaned and perfectly dry, close the road to all traffic,
or if this is not possible, close half of its width.
Select a warm, dry day in summer, heat the tarvia
(designated as "tarvia A" and having specific gravity
of 1.30) to 160° or 180° F., and evenly spread one-
third to one-half gallon per square yard. To heat it,
use kettles with furnace beneath, mounted on wheels,
or a tank-wagon fitted with fire-box; or a tank con-
taining steam-coils heated from a boiler; or, in some
cases, the tarvia is brought hot in tanks from the
factory (see pages 63 and 120 ).

Spreading. — To distribute it evenly over the road, if
none of the tar-spraying machines described on page
62 are available, or if there is no specially arranged
sprinkling-cart or " White" sprinkler, then the spread-
ing can best be done with an open hose from a tank-
wagon, or from the bottom of a wheeled kettle, or by
hand with pails. In either case, allowing it to flow

76

COAL-TAR PREPARATIONS.

onto the road and there having four men spreading the
tarvia with street-sweeper's fibre brooms.

Covering. — Traffic should be shut off from the tarred
surface for two hours or more, until the tarvia has
been practically absorbed, when new stone screenings
should be spread to take up any surplus of tar which
may remain on the surface, and the top should then be
finished by rolling. After a few days, the road should
be swept to remove any loose particles not bonded.

Cost. — The grade of tarvia thus used is "heavy,"
having specific gravity of 1.30, and being known as
"tarvia A." This may cost $500 to $700 per mile of
sixteen-feet roadway, varying with the cost of screenings
and with the freight-rate on tarvia.

COLD TARVIA TREATMENT.

This grade of tarvia is " lighter" than "A," having
a specific gravity of 1.10, and it is designed for use at
less cost (about half that of "A"), without heating,
and also without need for covering with screenings.

Spreading. — Any unskilled workman can apply it
with a hand-watering pot to a dry, hard, broken-stone
roadway, after sweeping the surface clean with a com-
mon broom. This grade of tarvia was first used in
September, 1907, on the Merrick road between Bellmore
and Wantagh, and at Oyster Bay, and at Hyde Park,
all on Long Island near New York. The resulting
surfaces are shown in views on page 79, where the
fragments of stone forming the mosaic-like surface can
be plainly seen but are firmly held in a matrix of tar
and dust. These roads are macadam which had been
stripped of the protective layer of screenings by the

77

ROAD PRESERVATION AND DUST PREVENTION.

passage of many motor-cars at excessively high speed,
so that the one and one-half inch fragments of stone
were exposed; prompt treatment was needed to save it.
The "B" tarvia was put, cold, into the tank of an
ordinary watering-cart to which was fitted a special
sprinkler, consisting of a one and one-half inch pipe,
perforated with eight one-eighth inch holes distributed
over each inch of length. The road-surface was first
swrept clean and was then sprinkled with one-third
gallon per square yard, which was then allowed to
spread and be absorbed. No brooms were used on
the tarvia, which was at once covered with the sweep-
ings from the adjoining roadside. Traffic was not
interrupted during or after the application.

Results. — There were no objectionable features; it
did not track, nor was it picked up by motor-car tires;
it gradually cemented the binder in the road-surface to
resemble asphalt, so that the road could be cleaned,
and the binder dust was no longer sucked out by the
rubber tires of passing motor-cars.

Cost. — One treatment is intended to prevent dust
and to reduce wear for a year at an average cost of
three cents per square yard, or $300 per mile of
sixteen-feet roadway.

MASSACHUSETTS ROADS.

On the main roads radiating from Boston, macadam
of the best character has been built and maintained by
the Massachusetts Highway Commission, and has been
subjected to exceptionally heavy and fast motor-car
traffic, as well as to the traffic of many horse-drawn
vehicles. Franklin C. Pillsbury, division engineer of

78

EAST MAIN STREET, OYSTER BAY, L. I., N. Y.

MERRICK ROAD, BETWEEN BELLMORE AND WANTAGH, L. L, N. Y.
COLD APPLICATIONS OF TARVIA "B."

79

ROAD PRESERVATION AND DUST PREVENTION.

the Commission, states that the motor-car traffic was
so injurious during 1906 and 1907 that, if newly built,
the roads would need resurfacing in two years, and
that if not preserved by some new method little would
be left of some of these macadam roads in 1908.

TARVIA ON PARK ROADS.

Roads maintained by the Massachusetts Metropolitan
Park Commission are described by John R. Rablin,
engineer of the Park Commission. Three and one-half
miles of park roadways were tarviated in 1906, using
hot tarvia "A," covered with screenings. After a year
of use, including the severe winter of 1906-7, about half
of this was re-treated during July and August, 1907.
From about one-ninth of. the whole, the surface layer of
tar and screenings scaled off in pieces one-quarter inch
thick when the frost came out in the spring of 1907,
evidently as a direct result of an excess of screenings
which was left on the road when the tarvia was applied
and which prevented the tarvia from penetrating at the
spots so covered. In general, the winter had no bad
effect on the parts properly treated.

Cost. — The average cost of the 1906 treatment, using
tarvia "A" hot, and including screenings, was about
six and four- tenths cents per square yard, and the
re-treatment in 1907 cost about the same. Meantime
the roadways were free from mud and dust. During
1907 other park roadways in the same system,
equivalent in all to ten miles of sixteen-feet road, were
treated with tarvia "A" at costs ranging from five and
eight-tenths cents to nine and three-tenths cents per

80

COAL-TAR PREPARATION.

square yard, varying with the condition of the roads,
necessitating more or less labor, the cost of which
ranged from one cent to three cents per square yard.
The cost of the tarvia varied with the quantity, from
two and one-half cents to three and eight-tenths
cents per square yard, depending also upon the
road condition.

DEFECTS.

On some portions of these roads the tarvia and screen-
ings gathered in bunches by a peculiar and unexplained
action; this did not injure the effectiveness but was
unsightly. This same bunching has been observed else-
where and has not been traced to faults in the road-
surface, which was in each case put in perfect order
before beginning the tarvia treatment. The bunches
gradually wear off and leave no break.

LYNN, MASS.

One of the most marked instances of the good results
from tarviating a road has been at Lynn, Mass., where
the Massachusetts Highway Commission built, in 1906, a
mile of good macadam across the marshes, where it was
fully exposed to sun and wind, and had as much high-
speed motor-car traffic as any road in Massachusetts.
As the result of these conditions the road had to be
re-surfaced in one year after completion.

Removal of Crust. — One month later, in July, 1907,
tarvia "A" was applied, after first removing a half-inch
crust of screenings which had been wet with salt water
and had become so hard that harrows and picks were

81

ROAD PRESERVATION AND DUST PREVENTION.

used to loosen it at considerable cost. Where small
patches of this crust were inadvertently left, it was after-
wards necessary to remove them also.

Methods. — The tarvia was brought, still hot, from the
works in Lynn, where it was prepared; but it proved
that the best surface was made where the coolest tarvia
was used. The location made it necessary to permit
travel during tarviating, and half of the width was
therefore treated at a time, with the result that the
lapping of the two coats shows at the center and is
unsightly.

Cost and Results. — The average cost was about eight
cents per square yard, including the covering of the
tar with coarse, quarter-inch sand, which was found
to be more effective than fine sand. As the result of
tarviating this road, it was free from dust and showed
practically no signs of wear from the passage of many
high-speed motor-cars during the next four months of
1907.

WAYLAND, MASS.

New Surface. — At Wayland, Mass., in 1906, a new
broken-stone surface was put upon parts of an old
macadam road. It has usually been considered that a
new surface should be used for at least a month before
treatment with prepared tar; but in this, case the clean
newly-rolled stone was at once tarviated without any
preliminary spreading of the usual screenings and
water. The results of the tarring were best on the
newly surfaced parts. For the material to cover the
tarvia, various grades of sand and of stone screenings
were tried, and the best was found to be the one-

82

COAL-TAR PREPARATIONS.

quarter inch, or "pea," stone from which all free dust
had been removed.

NEWTON, MASS.

Charles W. Ross, widely known as one of the most
experienced road-builders in the United States, formerly
State Highway Commissioner of Massachusetts, who
has built and maintains the model road system of the
Newtons, used tarvia "A" in 1906 and 1907 on the
fine macadam roadways in Newton, Mass., adjoining
Boston, where the high-speed motor-car traffic is excessive
and destructive, especially on Commonwealth Avenue,
which extends from Boston through Newton.

Methods. — In July, 1906, where the motor-cars had
completely taken off the binding material and had
left the one-inch stones bare and beginning to ravel,
he swept the surface as clean as possible with a
street-sweeping machine, and then spread about one-
half gallon of hot tarvia per square yard, covering it
at once with a thin layer of one-quarter inch sand or
fine, screened gravel (avoiding the dust of screenings)
and then rolled it. This formed a tarviated surface
which stood well through 1906, and improved during
1907, when more similar work was done on adjoining
roads.

Cost. — The itemized cost of the work was:

Tarvia "A, " at 8 cents per gallon 3T^ ct. per sq. yd.

Screening, or coarse sand T77 " "

Labor, cleaning, spreading, etc 4T3^ " "

Teaming, hauling tarvia, sand, etc i^ ' c "

Rolling T6Q- " "

Total n^ " "

83

ROAD PRESERVATION AND DUST PREVENTION.

On roadways having very heavy teaming, Mr. Ross
has swept and spiked the surface, covered it with a
layer of one-inch stone, rolled it smooth, applied one
and one-half gallons of hot tarvia "A" per square yard,
covered this with screened gravel and rolled again till
hard. All this cost nineteen cents per square yard, but
Mr. Ross believes that it will last four or five years, and
that it is well worth the extra material used.

PENETRATION.

In all these applications of tarvia in the vicinity of
Boston, the material was of grade "A," specific gravity
about 1.30, and it was all heated to 170° to 180° F.
or more, to facilitate spreading by brooms. The heat-
ing aids distribution, but has little or no effect upon
penetration, which varies on these roads, which are
exceptionally good, from one-half inch on very hard,
smooth surface to three-quarters of an inch or more
in some cases.

RHODE ISLAND ROADS.

In the State of Rhode Island during 1906 and 1907,
the State Board of Public Roads tarviated several State
roads, and among them was one in the town of Tiverton,
R. I. The operations are described by Asst. Engr.
Arthur W. Blanchard, Assoc. Prof, of Civ. Engineering
in Brown University.

Methods. — The road was swept in the usual way
with stiff brooms until the mosaic surface of the No.
2, or top course, was exposed, when hot tarvia "A"
was poured upon it and spread by brushes, and a thin
coat of fine sand was then spread over the tarvia.

84

COAL-TAR PREPARATIONS.

Steep Grade. — The section thus treated was on a
grade of seven and one-quarter per cent, and the
action on this steep grade was specially noted. The
tarviated surface proved effective in shedding the
water into the gutters, preventing the road from being
gullied, while, contrary to the experience of English
engineers with steep gradients, there was no trouble or
complaint as to slipping.

Results. — The road was subject to more than the
average motor-car traffic, being part of the interstate
trunk line leading to Newport; but the surface had
not scaled nor worn down to the stone after a season
of use, and it was free from dust. The cost was eight
cents per square yard.

On other roads similarly treated the tarvia coating
scaled off in spots and on the edges, but as a whole the
work proved to be satisfactory.

UNITED STATES EXPERIMENTS.

The United States Office of Public Roads, Logan
Waller Page, director, during 1907 conducted experi-
mental work of surface treatments at Wayland, Mass.,
in co-operation with the Massachusetts Highway Com-
mission. Crude coal-tar was used alone and in special
preparations and in various combinations with water-
gas tar, of each of which the composition was as follows
(see also page 59):

85

ROAD PRESERVATION AND DUST PREVENTION.

TABLE.
SPECIFIC GRAVITY AND COMPOSITION OF TAR PRODUCTS.

Kind of tar.

Specific
gravity.

Ammonical
water.

Total light
oils to
120° C. (or

338° F.).

Total dead
oils, i7o°C.
to 270° C.
(or to

518° F.).

Residue
per cent by
difference.

Water-gas tar

I 041

2 4%

21 6%l

*2 0%2

2d 0%3

Coal-tar

I 2IO

2 0%

17 3%4

26 o%5

CA 8C/6

Special tar preparation.

I.I77

0.0%

12. 8%2

47-6%7

39-6%6

1. Distillate mostly liquid.

2. Distillate all liquid.

3. Pitch very brittle.

4. Distillate mostly solid.

5. Distillate one-half solid.

6. Pitch hard and brittle.

7. Distillate one-third solid.

Methods. — The roads treated were mixed trap and
granite macadam about ten years old, being parts
of the main thoroughfare between New York and
Boston, sixteen miles from the center of Boston,
having heavy traffic of both motor-cars and teams,
producing excessive dust. The applications were made
during the month of August, 1907, only in dry and
warm weather, and were surface treatments only.
The general method was to sweep from the road
all loose dust and detritus just before the application
of the tar. This was applied hot or cold, as stated,
from a hose connected to a wheeled kettle or tank-
wagon, four laborers following with stiff, long-handled
brooms to spread the tar and to work it into the sur-
face. As the roads could not be closed to traffic, a light
covering of gravel or screenings was applied at once,
though better results would have been produced if
the tar could have been allowed to lie for several
hours before covering it. Finally, fine gravel or half-

86

COAL-TAR PREPARATIONS.

inch clean trap screenings was spread as a covering
material in sufficient quantity to take up all excess of
tar and to produce an even surface, when the whole
was rolled with a twelve-ton roller until firm and
smooth. The costs varied from nine cents to thirteen
cents per square yard, but these are stated to be high
because of the small areas treated and the excessive
repairs and renewals required in preparation,,

Conclusions. — The general conclusion here seemed to
be as elsewhere that coal-tar in some form was preferable
to water-gas tar in any form, being more effective as a
binder and more durable. The crude coal-tar showed
very favorably in comparison with the more costly special
preparation of coal-tar. This initial saving was some-
what offset by the fact that the crude coal-tar required
heating to a temperature of at least 145° F., ranging up
to 195° F., while the prepared coal-tars could be used
cold. The slippery surface during frosty weather was
an objection which was common to all the coal-tars.

The experiments led to the conclusion, as expressed
by Director Page, that the surface treatments with tar
as above described, are palliatives rather than preventives
of dust, and that some more permanent method of using
coal-tar is essential for satisfactory results (see page 116).

APPLIANCES.

Crude methods were used in all these operations,
although the engineers in charge appreciated the desir-
ability of the improved appliances used in France and
in England for similar works (see pages 70 and 89).

Heating. — The Boston outfit consisted of two five-
barrel heating kettles mounted on wheels, one pair of

87

ROAD PRESERVATION AND DUST PREVENTION.

horses to move them, twelve to fourteen laborers to
sweep the surface and to spread and cover the tarvia,
and teams to haul sand and screenings as needed.
The Rhode Island outfits were similar. The hot tarvia
was led from the bottom of each kettle through a pipe,
valve, and hose, from the open end of which latter it
flowed by gravity out upon the road-surface where
hand-brooms were used to spread it. No attempts
could be made to spray the tar, nor to force it into
the road, nor to get uniformity and rapidity of flow
by pneumatic pressure. Under these restricted condi-
tions, 1200 feet of sixteen-feet roadway, or 2000 square
yards of surface, was an average day's work, or less
than one-twentieth of the rate of work of the best
machines in England and France, where much better
penetration is also secured.

THE " WHITE" MACHINE.

Spreading— -The " White" machine, made by Theo-
dore F. White of Los Angeles, California, and gener-
ally used in forming the petrolithic roads of that
region, has also been used on some of the New York
and Massachusetts oiled roads. It is a patented
attachment to the rear of an ordinary sprinkling-tank
by which the gravity flow of the contents of the tank,
usually heated crude asphaltic oil, is controlled and
regulated in width of application varied from eighteen
inches to six feet, by gauges and valves, so that two
men with four horses treat half a mile of sixteen-feet
road per day. This machine would seem to be well
adapted to applying heated tarvia "A," or cold tarvia
"B," or any thin tar preparation.

TAR-SPRAYING MACHINES.

AITKEN'S.

The best of the tar-spraying machines (page 70) is
the "Aitkens' patent pneumatic tar-spraying apparatus,"
made by Thos. Aitken, M. Inst. C. E., Cupar, Fife,
Scotland, by which coal-tar, cold, can be sprayed in
varying quantities as desired, under sustained pneumatic
pressure sufficient to cause penetration to depth of one
to three inches into the hard surface of a used macadam
road. It can be fitted on an ordinary watering-cart,
using the tank to carry the supply of tar, and attaching
to the cart-frame the compressed-air "receiver" and the
pump, valves, sprayers, and devices, all actuated by
power from the wheel-axle of the horse-drawn cart.
A large sized machine is motor-driven.

Attached back of the tank is the " receiver," which is
a steel cylinder into which is first forced air at 100 pounds
to 150 pounds pressure per square inch by means of
the same force pump which also draws the tar-supply
from the tank. When this air pressure is reached, as
shown by a gauge, the pump is connected to the tank,
and the receiver is then half filled with tar, causing
the pressure in the receiver to rise to 200 pounds to 250
pounds per square inch, when the machine is ready for
operation, for which only two men are required. The

89

ROAD PRESERVATION AND DUST PREVENTION.

outlet-valve is then set to give a fine spray, or a coarser
one, as desired, thus varying the quantity of tar used
from about one-ninth gallon to about one-fifth gallon
per square yard of the surface being treated. The supply-
valve from the tank being meanwhile regulated to equal
the outlet and to thus maintain the uniform pressure in
the "receiver."

The method of using this machine to tar roads is
described in the 1907 edition of Aitken's " Road-making
and Maintenance," in effect as follows, the author and
inventor being a recognized English authority on road-
construction :

SPRAYING NEW TAR-MACADAM.

When a new macadam road is to be treated with tar,
the perfectly dry broken stone, after being spread over
the dry, properly drained, formed, and rolled roadbed,
is not rolled until the tar-sprayer has passed twice over
the loose dry stones, when the spray of tar, forced
through the fine spraying-nipples, penetrates the loose
mass of stone to a depth of three to five inches, with the
effect of covering all the surfaces of all the dry fragments
with a film of tar, which is thus equally diffused. If
the stone fragments are two inches to two and one-quarter
inches size, the course is then covered with a layer of
stone chips, or one-half inch screenings.* If the stone
fragments are three-quarter inch to one inch size, the
layer of stone chips is not needed.

Rolling. — The main point is to fill the voids in order
to secure binding with as little tar as possible, and to

* The writer considers it better practice to defer this covering of stone-chips
or screenings until after the base-course has been rolled and consolidated.

90

TAR-SPRAYING MACHINES.

roll thoroughly as soon as thirty to fifty yards in length
of the full width of the road is sprayed and covered
as described; it being necessary to complete a section
the same day that it is begun in order to avoid chance
of rain. After the rolling has brought the tarred stones
to a firm surface, it is again sprayed once, and then
covered with a one-quarter inch layer of screenings
and again rolled to a finished condition. The quan-
tity of tar thus used varies with the character and
size of the stone from four gallons to six gallons per
ton of stone, or an average of five gallons per ton,
which equals about six gallons per loose cubic yard.

Cost in England. — This rate for a two and one-third
inches finished thickness of rolled three-quarter inch
to one inch stones (three and one half inches loose)
would average about six-tenths gallon per square yard
of surface. A fair day's work for an engineman and
tar-sprayer, three men and two horses, using 625 gal-
lons of tar at four cents per gallon, would be to spray,
roll, and cover as described 125 tons, or 102 loose
cubic yards, of stone at a cost (in England) of twenty-
eight cents per ton or thirty-three cents per loose cubic
yard, making 712 square yards of a two and one third
inches finished surface, or 400 lineal feet of sixteen-feet
roadway per day of ten hours. This, in England with
wages at ten cents per hour and tar at four cents per
gallon, would equal a cost of four and one-half cents
per square yard, or three cents more than working with
water only. This equals $281 per mile of sixteen-feet
roadway.

Cost in United States. — In the United States, with
wages at twenty cents per hour and tar at five cents
per gallon, this would equal an added cost, for tarring

91

ROAD PRESERVATION AND DUST PREVENTION.

a two and one-third inches finished surface layer, of
five and one-half cents per square yard, or $516 per
mile of sixteen-feet roadway. The reduced cost of
maintenance and of cleaning is expected to offset this
greater cost of construction.

Result. — The macadam road thus built with good
tar is dustless and is better and more permanent than
the ordinary broken-stone roads built with water, pro-
vided that care is taken, so far as possible, to con-
solidate the stones by rolling so that the fragments
bond each other and do not depend upon the tar for
support.*

SPRAYING SURFACE OF OLD MACADAM.

For tar-spraying the surface of an old broken-stone
road, the surface must be clean and perfectly dry, taking
special care to look for and to correct slight depressions
in shaded parts of the road where moisture is likely to
linger even when the rest of the road is perfectly dry.
The tar-spray is applied to one-half of the width of the
roadway, turning traffic onto the other half for twenty-
four hours. This has been done to half of a sixteen-feet
road, by an Aitken tar-sprayer, at the rate of two-thirds
of a mile per hour.

Cost. — The cost of cleaning the road and spraying
the tar (when a horse-drawn apparatus is used) has
been about one-half cent per square yard for labor,
or $47 per mile of sixteen-feet roadway. Using one-
eighth gallon of tar per square yard with tar at five

* This feature is brought to its perfection in the graduated and adjusted
sizes used in bitulithic or quarrite roads; but such accuracy in filling voids is
not practicable in ordinary work.

92

TAR-SPRAYING MACHINES.

cents per gallon, the total cost for one application, in-
cluding labor as stated, would be one and one-eighth
cents per square yard, or $111 per mile of sixteen-feet
roadway. With the tar-sprayer attached to a motor-
driven van carrying 800 gallons of tar, greater lengths
of road can be treated per day, and the cost of spray-
ing is proportionately less. This does not include the
cost of dusting or sanding the surface to cover the
fresh tar, but such sanding would usually be required
in any case on any ordinary macadam road. Neither
does it include any allowance for the probable loss,
delay, and damage likely to be caused by rains which
may come upon the tarring work while it is unfinished.

TARSPRA.

The "Tarspra," of No. 20 Victoria Street, London, S.W.,
is another patented tar-spraying machine which is used
in a similar way and with about the same results as
the one just described. The "Tarspra" is made in
three sizes of 200 gallons, 700 gallons, or 1000 gallons
capacity each, and these are horse-drawn or motor-
driven. This apparatus takes the tar, either cold or hot,
by means of a double-acting force pump fixed at one
side of the tar-tank and actuated by chain-gear from the
wheel-axle. This pump forces the tar to atomizing
nozzles at the rear, where it is discharged in a fine spray
and distributed in an even coating under pressure of
200 pounds per square inch, the jets being so disposed
as to impinge upon each other in such way as to atomize
the spray, giving two inches of penetration. Thirty or
more of these machines of different sizes worked during
1907 in various parts of England, more particularly in

93

ROAD PRESERVATION AND DUST PREVENTION.

the County of Kent, tarring roads in some cases at the
rate of a mile per hour. Various improvements suggested
by practical experience will be embodied in future
machines.

LASSAILLY- JOHNSTON.

The "Lassailly- Johnston Patent Tar Road-binder,"
after having been successfully used on the roads in
France for several years, was introduced into England
in 1906 in an improved form as a competitor with
the two pneumatic machines just described. It dis-
tributes hot tar by gravity flow, depending upon auto-
matic brushes and absorption, instead of forcing a
fine spray as is done by the English machines. It is
more complicated than they are, consisting of two
vehicles, one in which to cook or heat the tar to
200° F. by means of steam-coils, and the other with
which to distribute it. Into the heater the cold tar
is drawn by a steam-created vacuum, and from the
heater the hot tar is forced quickly into the main tank
of the spreader, which is drawn by horses. From this
main tank its flow into the regulating-tank is controlled
by a float-valve which maintains a constant level, so that
the gravity flow through nozzles is uniform onto the road,
where four automatic weighted brushes spread it in an
even and smooth layer, one laborer following with a
hand-broom to insure complete spreading. The hot tar
is said to penetrate one to three inches into the road-
surface. It puts on a neavier coating than the spraying-
machines and one which is more enduring, but the
apparatus with its need for heating is more cumber-
some and slow to handle. It has, however, done a vast

94

TAR-SPRAYING MACHINES.

amount of good work both in France and England.
One of these outfits has covered 2500 square yards (or
over one-half mile of half the width of a sixteen-feet
roadway) per hour, using on it five tons of boiling tar,
thus doing the work better than was formerly done in
France by fifty men.

Cost.— The cost, where tar is bought at five cents
per gallon, is stated to be about six cents per square
yard for two complete coatings, including a covering
over the fresh tar of stone chips, trass, and dry Port-
land cement.

GOOD RESULTS.

The effect under ordinary conditions is to make the
road free from mud and dust for a year.

In France. — The resultant annual saving in the re-
duced cost of sweeping, mud-scraping, and repairs, is
stated by M. Heude, chief 'engineer of roads and
bridges of the department of the Seine and Marne,
to be one cent per square yard. The actual quan-
tity of material swept from a piece of thus tarred
macadam road near Paris being one-twelfth of the
amount removed from the same road during a similar
former period. The same engineer states that he tarred
24,000 square yards of macadam roads in 1903, 50,000
square yards in 1904, 150,000 square yards in 1905,
with good results throughout, the cost in some cases
being less than the savings, and that in future all
newly-made roads and streets will be tarred.

In England. — In England during the five summer
months of 1906, there were thus tarred by the Lassailly-
Johnston machines about 120 niiles of sixteen-feet roads,

95

ROAD PRESERVATION AND DUST PREVENTION.

including roads at Epsom, Shoreham, and Sutton, near
London, and at Hove and Worthing, near Brighton.

THWAITE.

The "Thwaite Anti-road-dust" machine is a steel
tank or boiler, fitted with a furnace-grate and a sprink-
ling apparatus. Tar and water are pumped into the
boiler where the tar is heated to 300° F., and steam is
also formed to give pressure for forcing the hot tar
through fine perforations of the sprinkler onto the road-
way. Meantime sprocket-gears from the wheel-axles
operate two force pumps, one to force dehydrated tar
into the boiler and the other to force air to add to the
steam pressure. The result is that the hot tar is so
atomized that the jets are nearly invisible until they
touch the road-surface which they penetrate effectively,
spreading tar over the surface in an enamel-like coating.
The apparatus is horse-drawn or motor-driven, and is
made in several sizes, the larger of which carries 300
gallons of tar. There is also an auxiliary tank, or tar-
boiler with furnace-grate, to give continuity of operation.
This system prefers that, in addition to the perfect dry-
ness which is required by all tar applications, the road-
surface shall be first heated with their hot roller to insure
its being dry and hot, and that after tarring, the tar
shall be covered with hot sand.

Cost. — The first cost of the comparatively simple
apparatus is moderate, and less than the others.
The work done is good and effective, but the cost of
operation as described is evidently greater than that
of either the Aitken, the Tarspra, or the Lassailly
machines.

96

TAR-SPRAYING MACHINES.

TARMACISER.

The "Tarmaciser" (of No. 7 Victoria Street, West-
minster, London) is a 35 H.P. steam-traction engine to
which are attached the various mechanical devices for
simultaneously cleaning and loosening the road-surface,
removing the dust, heating and distributing the tar, and
spreading it with automatic brushes, after which the
dust previously taken from the road is ejected over the
fresh tar and is then rolled by the steam-heated wheels
of the machine. It is most complete and complex,
requiring skilled adjustment and management and does
not seem adapted to general use.

CONCLUSIONS.

The number and the variety of these machines for
rapidly applying tar are indications of the general re-
cognition of the need for means to quickly treat great
lengths of roads during the short periods when weather
conditions are favorable, all authorities agreeing that
tar should only be applied when both air and road are
warm and dry (see " Conditions," page 67).

Their applicability to the original construction of new
tarred roads (see page 90), when surface treatment of
old roads is not needed, is an important economical
feature.

97

TAR-MACADAM.

SUMMARY.

This name is applied to any crushed-stone, or crushed
slag construction in which coal-tar, or a bituminous
cement, or a material containing coal-tar or bitumen, or
both, is used (instead of water) in binding the filler
between the fragments of stone, or slag; the tar or
bitumen remaining as a fixative to hold in place the
stone chips, screenings, or sand forming the filler,
" binder," or matrix for the fragments, thus aiming
to better the road (as compared with ordinary, water-
built macadam) by excluding water, reducing wear and
preventing dust. The term is used in distinction from
the surface treatment, or " tar-painting," described in
the preceding pages.

Tar-macadam may consist of a tarred three-inch sur-
face layer only, as described on pages 82, 105, and 107.
Or more usually of tarring all the fragments in the
entire road, either before spreading as described on
pages 105 and 109, or after spreading in place on the road,
as described on pages 107 and 118; or the "Gladwell"
system, as describedon page 111; or the most perfect
form in the bitulithic pavement, as described on
page 127.

98

TAR-MACADAM.

COMPARATIVE COST.

Any good form of the cheaper tar-macadams costs
about one-third more than the ordinary water-built
macadam of the same kind and depth of stone, because
of the added cost of the tar or bituminous cement, and
also because of the necessary restrictions as to working
only in warm and dry weather, and also the need of re-
pairing the injuries done by rain coming on incomplete
work. But these initial increased costs are offset, when
the construction succeeds, by longer life of the road and
by less expense for cleaning, maintenance, and repairs.

RESULTS.

When good, a tar-macadam road is practically dustless
and noiseless, offers little tractive resistance, and endures
the passage of the rubber tires of high-speed motor-cars;
and as it sheds water, it is not heaved nor disintegrated
by frost. It has the disadvantage, in common with
other pavements, of being slippery when frosty. Of the
several modified forms, the cheapest successful one seems
to be the "Gladwell" system, described on page 111.

HISTORY.

Tar-macadam roadways were first built on the London
road at Nottingham, England, at a date variously stated
as 1840 and 1845, and at Sheffield soon after. Other
similar roads have since been built at many times and
places in England and in France, and some in the
United States since 1900. The earlier ones used crude
coal-tar, mixed by hand with various kinds of stone,

99

ROAD PRESERVATION AND DUST PREVENTION.

and often produced failures because of the poor quality
of the crude tar (see pages 68 and 71), or because of
rain or cold during construction. Many of the old
ones, however, are still in satisfactory use, as well as
many new ones.

In recent years the necessity of having properly refined
tar has become generally known (see page 71), and im-
proved appliances for heating and hand-mixing the tar
and stones have been used with much better results than
formerly as to cost and character; the mixing has been,
effectively done in some cases with an ordinary con-
crete mixer.

In 1901 the Warren Brothers Company of Boston,
Mass., proportioned, heated, and mixed the materials
mechanically, as described on page 127; and in 1904,
Brown and Clarke of Nottingham, England, produced
a steam-operated machine which mechanically heats and
mixes stones and tar, as described at page 102, preparatory
to spreading it, cold, upon the roads. Tar-spraying
machines, and tar-spreading machines adapted to tarring
the stone in place, after it has been spread on the road,
have been devised, and have been used, as described on
page 71, in both England and in France for the surface
tarring of roads, but these machines have not as yet
been much used for making tar-macadam for which they
are well suited, as described on page 65.

In 1901 there was originated in the United States, and
since widely used, the bitulithic pavement, well known
as being the highest grade of combination of broken stone
and bituminous cement, which is described at page 127,
with details of the 1907 type of portable outfit for build-
ing it.

100

TAR-MACADAM.

METHODS.

Tar-macadam is more used in England than else-
where, and the methods of construction there have been
radically improved since 1905. In February, 1906, at
a meeting of the Inst. of Civil Engineers, H. G. Whyatt,
M. Inst. C. E., borough engineer of Grimsby, who had
built tarred macadam roads during many years, de-
scribed a new equipment which he had just finished
at Grimsby (which was like one built - at Sheffield in
1902 at a cost of $5000) for the purpose of better
heating and tarring the broken stone, or blast-furnace
slag, and which was described as being an improve-
ment on former methods.

By Hand-labor. — It consists of cast-iron plates three-
fourths inch thick and ten feet by twenty-four feet in
area, supported on brick walls about three feet high
forming flues, heated by five furnaces in which con-
tinuous coal fires are maintained. Crushed stone, or
crushed slag, is spread over the hot plates in a layer
six inches to ten inches thick, and turned two or three
times, by hand, with shovels, until dry and hot, when
it is wheeled to a mixing- board, ten feet by four feet,
where three wheelbarrows full, or say half a cubic yard,
is assembled and hot tar composition poured over it,
turning meantime by hand-shovels until every fragment
is covered with tar. It is then put on a wheelbarrow
and tipped into a heap where it is left to "mature"
for six to nine weeks. The tar composition for treat-
ing one ton of slag is formed by boiling together for
one and one-quarter hours twelve gallons of crude coal-
tar, two gallons of creosote-oil and fifty-six pounds

101

ROADf PRESERVATION AND DUST PREVENTION.

of pitch, stirring meanwhile. For crushed stone, the
quantity is usually one-third less because of less absorp-
tion. Care must be used that the stones, or slag frag-
ments, do not get hot enough to burn the tar and make
it brittle. (A simple and effective rule is that the stones
must not be too hot to hold in the hand.)

Five men thus treat twenty tons, or say sixteen cubic
yards per day, the operation involving the hand-shoveling
of the materials at least seven times, after which it must
be stored as stated, before being again shoveled for transfer
to the road for use.

Cost. — The cost at English prices of three cents per
gallon for tar and creosote, $12.50 per ton for pitch,
and $1 per day for labor, must have been at least $1.20
per ton or $1.44 per loose cubic yard; for the tarring
of stone to form a finished thickness of six inches, this
would cost thirty- six cents per square yard for the tarring
only, which is excessive. At the prices in the United
States this would be increased sixty per cent, making it
fifty-eight cents per square yard, which is prohibitive.

By Machine. — In 1904 Brown and Clarke built and
used at Nottingham, England, a machine weighing
twelve tons and costing $1400, for heating, tarring, and
mixing mechanically, with the work of two men (in-
cluding the engine-runner), thirty-five tons of crushed
stone per day, using eight gallons of crude coal-tar and
sixteen pounds of pitch per ton, which, at the same
unit prices, cost for the tarring sixty-two cents per ton
or seventy-four cents per loose cubic yard, equal to a
cost for the tarring of stone to form a finished thickness
of six inches, of eighteen cents per square yard at
English prices, or twenty-nine cents at United States
prices.

102

TAR-MACADAM.

This improved equipment consists of a hopper into
which the crushed stone is tipped and thence fed auto-
matically into the longitudinal pockets of an inclined
cylinder with a worm conveyer, the whole operated by
a four-horse power engine. Underneath are two coke
fires which heat the cylinders and their contents and
dry the stone, and also heat two attached tar-tanks
which are mounted on a saddle over the revolving
cylinder, through which the stone passes slowly (mean-
tin, j being thoroughly heated and dried), and then
drops into the trough where it is automatically sprayed
with a regulated amount of heated tar and is turned
and mixed by the worm-conveyer, which moves the
tarred stone to the upper end where it is ready to be
stored for future use as desired. The quantity of tar
sprayed upon the stone is adjusted to the speed of
the machine, so that there is neither an excess nor a
deficiency.

Cost.— As has been detailed, this Nottingham machine
does the work of tarring at one-half the cost of the
similar work done by the so-called improved equip-
ments for hand-labor at Sheffield and Grimsby.

Another similar plant was equipped in 1906 near
Gainsborough, England, by Parry & Sons, where blue
lias limestone from their quarries is crushed and heated
and treated with refined tar, with which tarred limestone
a competitive section of 2300 square yards of tar-macadam
was built in 1906 at a cost of forty-four cents per square
yard, including all materials and labor complete. This
was claimed to be "as good as the best tarmac."

103

ROAD PRESERVATION AND DUST PREVENTION.

TARMAC.

Tarmac is a trade name for blast-furnace slag, coated
and rilled while hot with heated, refined tar and tar-
oils. It is manufactured and laid by the Tarmac Com-
pany of Ettingshall, Wolverhampton, near Birmingham,
and is more or less made wherever blast-furnace slag is
available, being shipped from the iron districts to all
parts of England.

HISTORY.

It was first laid in 1898 at Newark, near Nottingham,
and the success there led to use elsewhere. The slag
is crushed and screened into three sizes, like crushed
rock. It is dried as before described, on iron plates, or
in rotary cylinders, or is taken directly from the blast-
furnace while still hot, and each size is separately tar-
red, using twelve to fifteen gallons of prepared, refined
tar per ton of hot slag.

The road at Newark, near Nottingham, just mentioned,
was formerly maintained by an annual coating of crushed
granite, until 1898, when it was covered with a three
and one-half inch layer of the first "tarmac," which
lasted without repairs until 1905, when it was re-
surfaced with one and one-fourth inches of tarmac.
It is said to be free from mud and dust.

OBJECTIONS.

Slag, which is very porous and absorbs most tar, is
structurally weak and crushes readily under traffic, so
that there is much room for choice in selecting only

104

TAR-MACADAM.

such slag as is best suited to the purpose, its irregu-
larity making careful inspection necessary. Slag having
much sulphur or lime must be avoided. In making
shipments by rail during hot weather it is sometimes
found that so much of the tar has oozed out of the slag
and has settled in the bottom of the car-load that the
whole needs to be re-heated and turned before spreading
in place upon the road.

METHODS.

The treatment used to make tarmac at Grimsby
in 1906 is described on page 101, and is more or less
the standard method. In some cases the slag is taken
directly from the blast-furnace while it still retains
its original heat, saving the expense of drying it and
thus producing "tarmac" in its best form. It is
deemed best to store the tarred slag for some weeks or
months, or until the tar is absorbed and has "toughened"
as much as possible, and also until any excess of tar
shall drain off. Tarmac seems to have been more used
than any other material in making the so-called tar-
macadam roads in England, being in use by the road
authorities of seven counties from London to Birmingham
and Sheffield, and also by the authorities of eighteen
corporations and boroughs, of twenty-eight urban dis-
tricts and six rural districts.

Tarmac Surface. — When an old macadam road is
surfaced with tarmac, the usual method is to remove
all loose fragments and irregularities and to make
the top of the old road firm and with the regular
crown, and upon this to spread the tarmac of one inch
to one and one-half inch size, four inches deep when

105

ROAD PRESERVATION AND DUST PREVENTION.

loose, rolling this to a finished thickness of two and two-
thirds to three inches, covering the completed surface
with fine slag screenings or sand.

Tarmac Construction. — When the entire road is to be
made of tarmac, as at Grimsby, it is laid in three
layers, each separately rolled solid. For the bottom
course, fragments of two and one-half inch gauge are
spread four and one-half inches deep, loose, and rolled
to three and one-half inches; over this is spread a two-
inch loose layer of one-inch gauge, which is rolled to
one inch; over this is spread a one-inch loose layer of
three-eighths inch gauge, which is rolled to one-half
inch, the whole making a finished thickness of five
inches at the center and three inches at the sides. The
completed surface is then covered with fine slag screen-
ings, or fine sand, as in certain stages of weather it other-
wise becomes very slippery. The whole work must be
done in dry weather, and preferably in warm weather.
The water-proof character of the road is such that the
crown or camber may be half that required for ordinary
macadam.

Comparative cost. — In comparative constructions in
1907 at Gainsborough (not far from Nottingham where
tar-macadam originated) a "tarmac" road coating four
inches thick when loose and two and two-thirds inches
to three inches thick when solid, cost fifty cents per square
yard, while tar-macadam of blue lias limestone of the
same thickness cost forty-four cents per square yard, or
fourteen per cent more for tarmac than for tar-macadam.
At the same time and place, a coating of water-worked
whinstone (i.e., ordinary macadam) of half this thick-
ness cost twenty- two cents per square yard, or the same
as the tarred limestone for the same total cubic quantity.

106

TAR-MACADAM.

CRUSHED STONE TAR-MACADAM.

Tar-macadam roads in England when made of crushed
stone are usually of limestone, or of granite, or of trap,
basalt, or whinstone (three names for similar rock), the
extent of use being in about the order named; a hard,
tough rock which breaks with a rough fracture being
preferred when other conditions are equal. Preference
is sometimes expressed for a porous rock which can
absorb the tar, but the evident weakness of such mate-
rial makes it undesirable for road-work.

METHODS.

In cases where an old macadam roadway is to be
surfaced with tarred stone, the old road is stripped
to the desired grade and the low places made good.
The tarred stone of two and one-quarter to two and one-
half inches gauge is spread in a loose layer six inches
deep and is rolled to four inches; this is covered with
a two-inch loose layer of three-quarter inch to one-inch
gauge tarred stone, rolled to fill the interstices ; the whole
when solid is covered with a light coat of slag-screenings
or sand. A surface treatment of refined tar applied once
in two or three years serves to keep such a tar-macadam
road in good condition with ordinary traffic.

In some cases crushed stone without tar is spread
and rolled dry, and is then grouted or flushed with
boiling tar or bituminous mixture of tar, pitch and oil,
as described ; a covering of half-inch chippings or screen-
ings of stone being added and rolled. This method
chills the boiling tar or mixture on the surfaces of the
cold stones, reducing its wearing qualities, and it also

107

ROAD PRESERVATION AND DUST PREVENTION.

usually deposits an excessive quantity of tar at the bottom
of the mass of stone; in hot weather this excess works
to the surface and makes trouble. Such construction
is not desirable, and is so described on page 118.

COMPARATIVE COSTS OF TAR-MACADAM.

Local conditions vary so much that it is useless to
compare costs at different places. Actual results at
places where both the ordinary macadam and the tar-
macadam have been used are instructive.

In the Ethington district, near Manchester, England,
tar-macadam has been extensively used since 1894,
and has there been found to cost twice as much as
ordinary macadam and to last four times as long before
needing renewal, meantime having little dust or mud.

In Northumberland, tar-macadam cost one-third more
than ordinary macadam when crude means of hand-
mixing were used to tar the stone. The general use of
mechanical mixing, as described on page 102, is expected
to reduce the cost of tarred roads to rates little greater
than the cost of dust -and -water built or ordinary
macadam. In 1894 and 1895 J. George-Powell, now
engineer of the Godstone district, near London, built tar-
macadam roads in Pocklington, East Yorkshire, near
York, which roads were still in good condition ten years
after. In 1905, being still interested in tar construction,
Mr. Powell made a drive of 1200 miles through the nine
counties north of London, and found many tar-macadam
roads, some many years old, and some recently built,
and all of them were noticeable for their comparative
freedom from dust and mud. The workmen employed
upon them gave replies indicating considerable decrease

108

TAR-MACADAM.

in the cost of maintenance. His extended experience
led him to conclude that tar-macadam roads can be
made to last seven to eight years, with comparative
freedom from dust or mud and at less final cost, as com-
pared with three years' life for ordinary macadam roads,
which always have either dust or mud.

Tar-macadam made at Sheffield (where the method
has been used for the past forty years) with the base course
of tarred limestone and the top course of tarred slag, is
said by Charles Froggatt Wike, M. Inst. C. E., county
engineer, whose charge includes fifteen miles of long used
tar-macadam roads, to cost the same per square yard
as does the ordinary macadam made of crushed granite;
the cost of tarring the limestone and slag being offset
by their less original cost as compared with that of
granite, the final cost being fifty-four to sixty cents per
square yard, exclusive of foundations. He states that a
typical suburban road of tar-macadam, fairly flat and
having considerable traffic, shows an average annual
charge, including the initial cost distributed over four-
teen years and maintenance, of eight cents per square
yard per year. On another tar-macadam road with
lighter traffic, the average annual charge, including
initial cost distributed over the same term, and main-
tenance, has been five cents per square yard. Mr. Wike
urges the importance of keeping tar-macadam roads in
good order, and of tar-painting the surface every three
or four years, or as soon as they get rough. Tar-mac-
adam made at Nottingham, where all the materials are
at hand, costs forty-two cents to forty-eight cents per
square yard. Similar roadways made at Battersea in
London, where all the materials must be brought from a
distance, cost eighty-four cents to $1.08 per square yard

109

ROAD PRESERVATION AND DUST PREVENTION.

In the annual re-surfacing in June and July, 1905, of
the sixty-four feet roadway on the Victoria Embankment
in London, where the traffic is both fast and heavy,
comparative one hundred feet sections of tarred granite,
tarred limestone and tarred slag were laid, each of six
inches finished thickness. Crude methods must have
been used, as it took a month and a half to lay the total
of 2100 square yards. The granite failed at once and
the limestone in three months, and both were replaced
by ordinary macadam of Guernsey granite in November
of the same year. The tarred slag was somewhat better.
The failure of the tarred granite was attributed to wet
weather during construction. The limestone and the
slag were laid in dry weather. The costs were $1.08
per square yard for the tarred limestone and the tarred
slag, and $1.26 per square yard for the tarred granite.

In 1908 Arthur Brown, M. Inst. C. E., city engineer
of Nottingham (where tar-macadam is best known), in a
paper read before the Royal Sanitary Institute, stated
the cost of new tar-macadam, including foundations, to
be eighty-four cents per square yard, where ordinary
macadam, including foundations, costs sixty cents to
sixty-six cents per square yard. This tends to confirm
the estimate made on page 99 and elsewhere, that
tarring under average conditions increases the cost
one-third. Mr. Brown describes tar-macadam as being
noiseless and dustless, but as being conducive to side-
slip in "greasy" weather. It has been said that tarred
surfaces were unsafe on steep grades, but a ten per cent
grade in Nottingham is used by heavily loaded drays
passing down, aided by sanding when needed, which
agrees with the experience at Tiverton, Rhode Island, as
described on page 85.

110

TAR-MACADAM.

GLADWELL SYSTEM.

The "Glad well" system, mentioned on page 15, is a
method of surfacing macadam roads, either old or new
ones, with a tar-macadam top which gives some of the
effects of tar-macadam, as described, and at a less cost
which will probably lead to its general use.

SUMMARY.

It consists in imbedding a two-stone course of un-
tarred clean, crushed stone (usually two-inch gauge)
in and between two layers of tarviated, one-quarter inch
gauge, dustless stone chips, which form a matrix which
is worked, by judicious rolling, into the spaces between
the stone fragments from below upward and from above
downward, finally sealing the surface so as to be water-
proof by hot tarvia "A" and granite drippings,

HISTORY.

The system was devised by Arthur Gladwell, who
has charge of road construction and maintenance at
Eton, near Windsor, England, and was first used by him
on the road at Stoke Poges in July, 1906. It has since
been successfully used on the roads along the Thames
in that vicinity, and elsewhere in England. Its low
cost and ease of construction, and especially the fact
that most of the work may be done in ordinary
weather, will no doubt lead to its extensive use in the
United States.
\£ ;—.•-•- . ::•; .•'.; ' ,• - ...-". I Jj

111

ROAD PRESERVATION AND DUST PREVENTION.

METHOD.

The road to be surfaced must be made regular and
firm, the usual crown or camber may be flattened if
desired, and the surface of the foundation must be kept
cleanly brushed as the work proceeds. For the bitu-
minous binder or matrix, provide clean granite chippings,
free from dust and passing a quarter-inch sieve, and
thoroughly dried in a heater.

Tarring. — While still warm, but not hotter than 100°
F., these chippings are mixed with tarvia "A," heated
to 175° F., in the average proportion of fifteen gallons
of tarvia per cubic yard of chippings, less tarvia being
required in warm weather and more in cold weather.
Crude tar cannot safely be used, and tarvia is specially
advised by Mr. Glad well. The warm chips and the
hot tarvia are mixed gradually like concrete until they
form a plastic mass, which is preferably used at once,
but which may be kept forty-eight hours or longer,
provided the hardened surface of the pile is sepa-
rated and worked over with hot tarvia. (Evidently a
rotary concrete mixer could be well utilized for making
this mixture.)

Spreading. — This matrix is spread in a three-quarter
inch layer upon the prepared foundation, forming the
"sub-binder" over about six feet in length of the road,
and for about half its width, covering about forty-six
square yards of surface with one cubic yard of the tarred
material. It should be spread evenly and lightly, and
must on no account be trampled upon or consolidated in
any way until it has been covered evenly with a two-stone
course of two-inch to two and one-quarter inch clean,

112

TAR-MACADAM.

dry, crushed stone, a loose cubic yard of two-inch gauge
stone covering about fourteen square yards of surface.
Use stone forks (not shovels) to spread the stone, so as
to leave out all small pieces and flakes and dust. Bring
this layer of stone to within six inches of the forward
end of the " sub-binder" already laid, and then lay
another three-foot length of " sub-binder," following
with the two-stone coat, and always arranging so that
the workmen do not trample upon the " sub-binder";
also, leave a loose edge of both courses at the center line
of the road to insure a good joint when the other half is
built the next day. When the whole width of road must
be done at one operation, scarify the center or traffic
track for say twelve feet width, and remove the loosened
materials for use elsewhere. Sweep the scarified surface
clean, and then spread the " sub-binder" and the two-
stone coat, as before described.

Rolling. — The two-stone coat being ready on a section
of twenty-five or thirty yards in length of the road,
begin rolling at once, using a fairly light steam-roller
moving at slowest speed in order to press the stones
gently down into the matrix, and at the same time to
draw the matrix upward between the fragments. This
is not accomplished so well by a heavy roller as by a
light one judiciously used. As soon as the " sub-binder"
is seen to be working up between the stones, sprinkle
some of the same bituminous material lightly over the
top of the stones and carefully brush it into the surface
voids until they are fairly well filled, the binding mate-
rial or matrix thus working both upward and downward
under the action of the roller until the new surface of
the road is solid. Thus much of the construction may
be done in any ordinary weather and need not be con-

113

ROAD PRESERVATION AND DUST PREVENTION.

fined to the warm and dry weather usually required
for tarred construction.

Finishing. — For the completion or " surface sealing,"
warm, dry weather is essential. It is useless to attempt
it during wet weather. One-sixth gallon of heated
tarvia "A" per square yard of surface may be sprayed
over the surface by one of the machines described on
page 70, or it may be applied otherwise, the fresh
surface being at once covered with a one-quarter inch
layer of clean, dry, quarter-inch gauge granite or trap
screenings, of which one cubic yard will cover 180
square yards of surface. The road should then be well
rolled. If it is desirable to complete the surface sealing
by hand as the work progresses, as is often the case,
this may be done with hand-watering cans having
V-shaped lip-outlets, spreading one-quarter to one-half
gallon of heated tarvia per square yard and covering
it, as before described.

This description provides for a finished, Gladwellized
surface of two and three-quarter inches to three inches
finished thickness. If a thicker coating is wanted, omit
the "top-sealing" from the first course, apply another
layer over it, and "top-seal" the last. If a thinner coat
is wanted, as for roads having light traffic, reduce the
size of the stones forming the "two-stone" layer, and
reduce the thickness of the "sub- binder" proportion-
ately.

Cost. — On the roads thus built by Mr. Gladwell at
Slough and by George W. Manning at Staines, both near
Windsor, England, the greater cost as compared with
that of an ordinary macadam surface has been seven
cents per square yard. The lesser thickness required
reducing the quantity of stone and lowering the cost.

114

TAR-MACADAM.

The inventor finds that with proper organization 450
square yards of surface, or 250 feet of a sixteen- feet
road, can easily be completed in a day.

At prices in the United States the cost should not be
more than the cost of dust-and-water built macadam
plus twenty per cent.

Opinions. — The method is commended by H. Howard
Humphreys, Assoc. M. Inst. C. E., in 1908, in a paper
read before the Society of Road-traction Engineers in

SPREADING SCREENINGS OVER TARVIA (Jackson, Tenn.).

London. Practically a similar construction is proposed
by Logan Waller Page, Director of the United States
Office of Public Roads, as detailed on page 116.

TAR-MACADAM IN THE UNITED STATES AND CANADA.
SUMMARY.

There is as yet no general use of tar-macadam on
rural roads, such work being so far done only on a small
scale in an experimental way by the road departments of

115

ROAD PRESERVATION AND DUST PREVENTION.

some of the States, and by a few towns and villages.
The use of the high-class bitulithic and its imitations
has been confined to urban and suburban streets. The
United States Office of Public Roads did some useful
work at Jackson, Tennessee, in 1905, and the results
as published by Director Page have been generally read
and used as the basis for other experiments. The re-
port says:

"A tarred street is dustless in the same sense that an asphalt
street is dustless, though a fine sandy powder wears off as in the
case of asphalt. In driving over a tarred macadam road, the lessen-
ing of vibration and noise is at once noticeable. The ordinary
macadam produces a constant succession of slight jars upon a
steel-tired wheel and there is a relief felt at once in driving upon a
road treated with tar."

The United States Office of Public Roads continued
to give special attention to the subject during 1906 and
1907, and in circular No. 89, issued April 20, 1908,
Director Page expressed the opinion elsewhere quoted
that surface treatments were palliatives rather than dust-
preventives and that a more lasting method would be
"the use of well-tarred sand as part of the binding mate-
rial and to fill voids," applying a layer of such tarred
sand to the rolled base-course, over which the top course
should be spread and rolled until the tarred sand should
work down into the base-course and up into the top-
course. The surface being then finished by an applica-
tion of tar covered with fine chips or sand and rolled until
smooth and uniform. This suggested method is prac-
tically the same as the "Gladwell" system, described and
commended on page 111.

In Canada, tar-macadam has been used to a consider-
able extent by the cities of Hamilton, Toronto, and

116

TAR-MACADAM.

Ottawa. Hamilton (located midway between Buffalo
and Toronto) built several miles of tar-macadam in the
English method as early as 1880 and has maintained
and extended it since to a total of nine miles of thirty-
feet roadways in 1908 at initial costs of from seventy-
nine cents to $1.06 per square yard. Toronto has built
since 1902 about the equivalent of six miles of thirty-
feet roadways costing about $1.50 per square yard.
Ottawa, since 1902, has built about half as much, costing
from $1.24 to $1.57 per square yard. The latter being
particularly well built and successful in being clean
and dustless, but being too costly for other than city
streets.

METHODS.

In Rhode Island.— In 1906 and 1907 the State Board
of Public Roads of Rhode Island used tar in constructing
a macadam road on a main State highway, near Charles-
town, in method described by Assistant Engineer Arthur
W. Blanchard. The road is of special interest because
it is part of a main trunk line between New York, New-
port, Providence, and Boston, and is therefore subject
to the maximum of high-speed motor-car travel. The
macadam was built in much the usual way with the
addition of tar. The bottom layer of one and one-
quarter inch to two and one-half inch crushed stone,
six inches loose and rolled dry to four inches, was sprinkled
freely over the top with hot tar from dippers. Half -inch
to one and one-quarter inch crushed stone was then
mixed with hot tar by turning by hand-shovels and rakes
on dumping-boards until all surfaces of stone were fully
coated, when it was at once spread in a three-inch loose

117

ROAD PRESERVATION AND DUST PREVENTION.

layer and rolled to two inches finished thickness. A
thin coating of screenings and dust was then spread
and rolled upon the freshly tarred stone. The whole
work was done only when perfectly dry, and was begun
and completed each fair day at the rate of one hundred
lineal feet, or 154 square yards per ten hours.

Cost. — Five extra men did the tarring at a cost for
labor of six cents per square yard. One and one-
seventh gallons of tar per square yard was used,
costing ten cents per gallon, but this was partly offset
by a saving of one and three-quarters cent per square
yard from not using any water, making a total cost
for the tarring of sixteen and one-quarter cents per
square yard. The road thus built endured the severe
winter of 1906-1907, and the traffic through 1907,
without showing perceptible change and without
dust.

On the Narragansett Pier road, in 1907, tarvia "A"
was used in constructing a new tar-macadam road.
The lower course of six inches, loose, of untarred crushed
trap was rolled solid to four inches in the usual way
but without water, and upon it was spread two and
one-half inches to three inches of dry, untarred half-inch
to one and one-half inch crushed trap, which was lightly
rolled. The tarvia, which had been heated in tar-kettles,
was then poured upon the surface of the lightly rolled
top-course and was allowed to penetrate, going in one
to two inches. Eight- tenths gallon to one and six- tenths
gallons per square yard was used, varying according to
the amount of rolling and the size of the stone. Trap
screenings, half-inch to dust, was then spread over the
tarred surface three-quarters of an inch deep, and the
whole was then rolled until firm and smooth. The only

118

TAR-MACADAM.

added cost was for the tarvia. Similar English work is
described on page 107 as being undesirable.

In Massachusetts. — The comparative cost of tar-mac-
adam and ordinary dust-and-water built macadam in
Massachusetts is clearly discussed by Assistant Engi-
neer H. C. Poore, in the 1908 report of the Massachu-
setts Highway Commission, estimating that a dust-
and-water- built macadam of five inches finished thick-
ness costs fifty-three and one-third cents per square
yard, and that a similar tar-macadam road costs
sixty- eight and one-half cents per square yard, equal
to the cost of the ordinary macadam plus twenty-eight
per cent. The tar-macadam estimated upon consists
of an untarred base-course bound and filled with dry
screenings or sand and rolled until firm and three
inches thick. This to be covered with a two-inch
finished thickness of tarred top-course of half-inch to
two-inch stones (using a rotary concrete-mixer to coat
the stones with two-thirds gallon of tar for one-ninth
cubic yard of loose stone, or enough to make one square
yard of top-course). This course after rolling to be
covered by a top dressing of "pea" stone, or coarse
screenings, treated after spreading and rolling with four-
tenths gallon of tarvia " A" per square yard, which is also
rolled. These estimates are based upon the assumptions
that the subgrade is completed ready to receive the
macadam; that the crushed stone costs $1.25 per ton
(or about $1.50 per cubic yard), delivered; that tarvia
delivered on car costs seven and one-half cents per
gallon, and that the labor of tarring the surface costs
two cents per square yard. This construction is ex-
pected to eliminate dust and prevent ravelling at a reason-
able cost.

119

ROAD PRESERVATION AND DUST PREVENTION.

Kettles for Heating — Mr. Poore commended the use
of 500-gallon kettles to heat the tar in preference to
smaller ones (see page 87), and advised that the wheels
of the kettles should be fitted with five-inch tires, and
that there should be spigots at each end of the kettles
so that all of the contents might be run out when on
inclines, and that the hose should terminate in a funnel
attachment to deliver the hot tar in a broad, thin
stream.

120

ROCK-ASPHALT MACADAM.

SUMMARY.

This construction gives good results, but the cost of
transportation has limited its use to the vicinities of
the natural formations of the peculiar sandstones and
limestones which are impregnated with bitumen and
are known as " rock-asphalts."

The natural formations which occur in Arkansas,
Indian Territory, and Kentucky, are sand-rock im-
pregnated with a proportion of bitumen varying from a
trace to a maximum of thirteen per cent, six per cent
being about the least useful proportion.

The European supplies are those of France, Sicily, and
Switzerland, and are bituminous limestones formed by
natural combinations of about twelve per cent of bitumen
with about eighty-eight per cent of amorphous carbonate
of lime, and were first used for roads in Paris in 1854,
and since then have made the comparatively small
extents of asphalt pavements in European cities, being
too costly for general use and much more slippery than
the similar ' city pavements made from the American
sand-rock asphalts, which are also costly.

121

ROAD PRESERVATION AND DUST PREVENTION.

METHODS.

For less costly roadways in the cities of the south-
western States of the United States, sand-rock asphalts
from the formations in Arkansas and Kentucky have
been combined with ordinary macadam in an effective
way, which is described by Walter F. Reichardt, Assoc.
M. Am. Soc. C. E., city engineer of Little Rock,
Arkansas, in a paper read before the 1906 meeting of
the American Society of Municipal Improvements. He
has used the several kinds named and finds the Arkansas
sand-rock asphalt to be the easiest to use, it being richer
in bitumen and exceptionally good for rock-asphalt
macadam. At Little Rock, Arkansas, the method is as
follows :

CITY STREETS.

The subgrade is prepared in the manner usual for a
good macadam road, using special care to remove all
soft spots and to roll thoroughly.

Spreading. — The usual three-inch to four- inch base-
course of one and one-half inch to two and one-half
inch ordinary crushed stone is spread, filled with
dry sand, and rolled without water. Over this is
spread and rolled, dry, another three-inch finished
thickness of the same sizes of crushed stone as the
base, but without the sand filler. (The crushed stone
used is trap, granite, limestone, or chert, whichever
is most available.) Over this second course is spread
a top layer sufficient to fully cover, formed of equal parts
of ground sand-rock asphalt and half-inch to one-inch
crushed stone.

122

ROCK-ASPHALT MACADAM.

Rolling. — This layer is rolled with a heavy steam-
roller until firm and smooth; dry Portland cement
is swept over the surface and the road is opened to
traffic.

Results. — The pavement is not slippery, because the
fragments of stone imbedded in the ground sand-
rock asphalt give a good foothold. It needs care and
must be kept clean.

Cost.— Its cost in Little Rock has been $1.40 per
square yard, entirely preventing its use on other than
city streets. A cheaper and more generally useful me-
thod is the following:

SUBURBAN ROADS.

In 1907 the United States Office of Public Roads,
Logan Waller Page, director, made an experimental
road at Bowling Green, Kentucky (as described in
Cir. No. 89, of April 20, 1908), using Kentucky sand-
rock asphalt, in which bitumen ranged in proportion
from six per cent to eight per cent with a maximum
of twelve per cent.

Kentucky Sand-rock Asphalt. — This is quarried like
other rock and is crushed in the usual way into frag-
ments to pass a two-inch ring, and the total product
of the crusher is then taken to a series of roll-crushers
which reduce it to a mass of separate grains of sand,
each fully coated with a film of bitumen sufficient
to cause the grains to adhere under pressure and
giving the sand a rich, dark-brown color. (In this
condition it costs $5 per ton f.o.b. cars at Bowling
Green, Kentucky, one ton being equal to twenty-seven
cubic feet loose measure.) If this sand is warmed in

123

ROAD PRESERVATION AND DUST PREVENTION.

the hand, the bitumen becomes soft and semi-fluid, so
that the grains separate of their own weight, but when
chilled (to about 60° F. or less) after compacting, it
becomes hard and tough.

On an old roadbed reformed and crowned, crushed
limestone of one inch to one and one-half inch size,
was spread four inches deep and rolled once, dry, merely
to turn down the sharp edges and to form an even sur
face. (This reduced the voids to probably about
twenty-five per cent.)

Spreading. — The ground sand-rock asphalt above
described, was then spread to a depth of one and one-
half inches over this undisturbed surface, being thrown
on with shovels from wagons or dumping-boards at one
side of the road, one ton thus covering twenty-four and
one-half square yards. Care was taken to break all
lumps of the ground sand-rock asphalt and to work it
into the interstices of the crushed stone.

Rolling. — Meantime the steam-roller was kept moving
back and forth, working always parallel with the axis
of the roadway and from the outer edge to the center;
after the fourth or the fifth rolling, the sand-rock asphalt
was forced into the voids and the surface became firm.
The behavior of the ground sand-rock asphalt varied
with the temperature, the bituminous sand working into
hard, rounded lumps in the early morning when the
temperature was about 65° F., and then spreading
smoothly and compacting evenly as the temperature
rose to 70° and 75° F. and upward. A light rain occur-
ring at 65° F., impeded work, and portions which were
then built did not compact and become hard for several
hours after others built later.

124

ROCK-ASPHALT MACADAM.

Results. — The road when opened to traffic rutted badly
under heavy loads at first, and was also seriously cut by
hoofs. These bad features disappeared gradually after
three or four days, and no trace of the ruts or the cuts
remained at the end of a week, when the road looked
like a sheet-asphalt pavement which had been some-
time used. After four months it had undergone no ap-
preciable change, and incisions into the surface showed
no drying nor hardening of the bitumen, the sand particles
moving as formerly when warmed in the hand. The
pavement thus formed is dustless and the surface shows
no appreciable wear.

Cost. — The total cost for material and labor (including
shaping of subgrade and buying ground sand-rock
asphalt and crushed stone) was forty-seven and two-
third cents per square yard, or about the cost of similar
thickness of ordinary dust-and water built macadam.

It is evident that this bituminous sand formed by
crushing the twelve per cent sand-rock asphalt would be
well suited to use in the Gladwell system, described on
page 111.

Sheet Asphalt. — This bituminous sand produced by
crushing and rolling Kentucky sand-rock asphalt has
been used in the United States to make sheet-asphalt
since 1890-1892 when ten miles on fifty-two streets were
paved with it in Buffalo under five-year guarantees; the
results were good, the repairs during eleven years aver-
aging one cent per square yard per year. In San Fran-
cisco, Front Street was thus paved in 1890 and was in
good condition without repairs after eleven years of
heavy use.

Methods. — To form these pavements, the bituminous
sand produced by grinding the rock is heated to 300

125

ROAD PRESERVATION AND DUST PREVENTION.

degrees F., and is spread hot directly upon the clean,
dry, six-inch concrete base where it is rolled and rammed
into a compressed layer two inches thick. No "flux"
and no "binder-coat" is needed, the bituminous sand
forming the entire surface. The cost was about the
same as the more common artificial sheet-asphalt or
$1.40 to $2.00 per square yard including the usual con-
crete base and the guarantee.

Binder for Macadam. — The success in this use indi-
cates its availability as binder for macadam.

126

BITULITHIC PAVEMENT.

SUMMARY.

This is the best known combination of crushed stone
and bituminous binder, and is composed of fragments
of stone which are held firmly and free from attrition,
and hence form no dust. It differs from other bitumin-
ous macadams in that the proportions of the several
sizes of fragments of crushed stone, from two inches
in size down to dust (which form about nine-tenths of
the final mass), are accurately determined and are so
combined in such proportions of the six or more sizes
that the final voids between the fragments after rolling
do not exceed ten per cent, or less than half the ordinary
voids in rolled stone. This puts the fragments into
actual and firm contact, so that the addition of ten to
twelve per cent by weight (twelve to sixteen per cent by
bulk) of bituminous compound fills the remaining voids
and makes a solid and impervious mass. This result
requires experienced care and skill in selecting and com-
bining the best materials, including testing and analyzing
the components of the bituminous cement. The pave-
ment thus produced is one which water cannot penetrate,
and it supports the passage of heavy and high-speed

127

ROAD PRESERVATION AND DUST PREVENTION.

vehicles without any loosening of the bituminous filler
and without abrasion of the fragments of stone, so that
no dust comes from the pavement or its materials.

OPINIONS.

With the present general knowledge of it which has
been acquired since 1901, opinions are now of less
moment than in its first years of use, when it was
strongly commended by the writer and others who were
quoted, in the 1902 edition of "City Roads and Pave-
ments," and again in the 1906 edition, where it is de-
scribed in detail. One of the best and most weighty of
the opinions which have been published is that of George
W. Tillson, president of the American Society of Munic-
ipal Improvements, Chief Engineer of the Bureau of
Highways of the Borough of Manhattan (New York
City proper), and author of the standard book, "Street
Pavements and Paving Materials," who said before the
Franklin Institute in 1906:

"Bitulithic pavement is made of crushed rock and bitumen, the
particles of stone being mixed in certain scientifically predetermined
proportions as to sizes, so as to provide a maximum of density and
a minimum of voids, so that the resulting bituminous concrete is
nearly as dense as a block of solid stone with a surface that offers
as little resistance to traction as asphalt, but one that is not slippery,
because the fine stone used in the finishing course provides a gritty
surface, similar to macadam, which affords secure footing for horses
at all seasons."

In November, 1907, at the meeting of the Massachu-
setts Highway Association (see page 13) to discuss "sup-
pression of dust,1* Franklin C. Pillsbury, expressing the

128

BITULITHIC PAVEMENT.

opinion of the Massachusetts Highway Commission, of
which he is division engineer, said:

"The bitulithic pavement is undoubtedly the best form of pave-
ment to give the desired results (durability and freedom from dust
under fast motor-car travel), but it is too expensive for many loca-
tions."

A practical expression of opinion was recently given
by the Chicago South Park Commission, which selected
it for use on several miles of fifty-feet boulevards after
two weeks of investigation and after competitive bids for
other forms of pavement.

HISTORY.

It was first used in 1901 in Pawtucket, R. I., where
it was laid on a twelve per cent grade on Harvey
Street. During the same year sample areas were built
in seven cities, aggregating about one mile of thirty-
feet width. The success was immediate, and the use
increased each succeeding year, so that at the close of
1907 six and one-half million square yards, equal to
422 miles of thirty-feet roadways, had been laid in one
hundred and sixty-six cities of the United States and
Canada, including cities in the region of extreme cold,
as at Edmonton, province of Alberta, Northwest Canada,
and Glace Bay, Nova Scotia, and in the South at El Paso,
Texas, and at Atlanta, Georgia. This wide-spread
success has induced imitations and consequent litiga-
tions, which are further evidences, if such were needed,
of the merits of the construction.

129

ROAD PRESERVATION AND DUST PREVENTION.

METHODS.

The base for bitulithic pavement is varied to best fit
the local conditions. On gravelly soil which can be
rolled solid, a bituminous base can be used, formed of
crushed stone or slag of two inches to three inches size,
spread to a uniform depth of four to six inches and

LAYING BITULITHIC PAVEMENT ON E. MAIN STREET, SPARTANBURG, S. C.
(See larger photograph of Flush-coat Spreading Machine and Stone-
sprinkling Machine shown in background.)

rolled, dry, with heavy steam-rollers. This is followed
by a coating or "binder" of hard, waterproof, bitu-
minous cement. On soil which is sandy, or which
cannot be rolled to be solid, an ordinary six-inch base
of hydraulic-cement concrete is made, with the addition

130

BITULITHIC PAVEMENT.

of tamping into its plastic surface fragments of crushed
stone in order to make it rough. On a formerly paved
street, the old pavement can be used as a base for a
bitulithic surface.

Upon the base of whichever sort, the "wearing sur-
face" is spread and while still hot is compressed with
heavy rollers to a finished thickness of two inches.

FLUSH COAT SPREADING MACHINE.
(Patented.)

Used in spreading the quick-drying
bituminous flush coat on the sur-
face of the bitulithic pavement.

STONE- SPRINKLING MACHINE

(Patented).

Used in sprinkling hot stone chips on
the surface of the bitulithic pave-
ment, to be rolled into the bitu-
minous flush coat.

Proportions. — This wearing surface is formed of the
best and toughest available crushed rock, varying in size
from a maximum of one and one-half inches and one inch
down to dust, which material is heated and dried in

131

ROAD PRESERVATION AND DUST PREVENTION.

rotary drums and is then screened in rotary screens,
which separate it into six or more sizes. Tests are then
made to determine the proper proportions of the different
sizes which will produce the densest mixture having the
smallest percentage of voids. These tests are daily
repeated by the makers during the progress of the
work upon samples taken from it, in order to have
assurance of perfect uniformity in the pavement.

Mixing. — The determined proportions by weight of
each size are run through the hopper of an automatic
weighing-machine, into a mechanical mixer, at a tem-
perature of 250° F., and are there combined with an
accurately weighed proportion of heated bituminous
cement, of which the composition is the result of
close tests and which is carefully determined to be of a
sufficient quantity (but not too much), to fill all final
voids by coating the faces of all particles of stone and
of sand and of dust, and also providing a slight surplus
as a " filler."

Spreading and Rolling. — When thus mixed, the hot
stone and bitumen is hauled to place on the road, and
is there spread and rolled while hot, using a twelve-
ton to twenty-ton steam-roller to assure the maximum
compression which crowds the bitumen into all the
voids and forces out all air-bubbles, and makes the
most dense surface possible. Upon this surface, filling
it and making it sticky, there is then poured and rubbed
a coating of quick-drying bituminous cement heated
to 250° F., over which is at once spread a quarter-
inch layer of small stone chips which are rolled into
the sticky coating and form a final wearing surface,
the size of these chips being larger as the grade is
steeper.

132

Dismantled ready for shipment.

Set up ready for operation.

ONE-CAR PORTABLE BITULITHTC RAILROAD PLANT. (PATENTED).

133

ROAD PRESERVATION AND DUST PREVENTION.

The elaborate outfit of laboratory and machinery and
skilled direction required to successfully produce this
pavement would at first seem to limit construction to the
vicinity of permanent plants, and this idea is strengthened
by visiting such a plant and examining the work in pro-
gress. There have, however, been built and patented
by the Warren Brothers Company, of Boston, Massachu-
setts, a number of " semi-portable bitulithic paving-
plants," each permanently set upon a platform-car, of
which full illustrations showing details are here given.
These outfits make it possible to build this pavement
in many widely distant places and to give to all of them
equally reliable results. The six illustrations showing
this " semi-portable bitulithic paving-plant (patented)"
are all lettered to accord with the following key:

A. Boiler and engine.

B. Rotary driers for heating and drying stone.

C. Elevators for delivering the stone to the driers.

D. Elevators for conveying the heated stone to the separating-

screens.

E. Sectional screen for separating the stone into several sizes.

F. Sectional bins for storing the several sizes of stone after sepa-

ration, and delivering same to the weighing-box.

G. Weighing-box resting on a multiple seven-beam scale for accu-

rately weighing each size of stone in predetermined propor-
tions and delivering same into the mixer.
H. Twin pug mechanical mixer, having two shafts revolving in

opposite directions with arms or blades interlocking each

other.
I. Mixing platforms under which wagons back for taking the

bitulithic mixture as delivered from the mixer.
J. Ogee-bottomed bitumen-melting tanks.
K. Bitumen weigh-bucket conveyor and dial-scale, so arranged as

to indicate both gross weight and tare.
L. Rotary exhaust fan for providing induced draft to the rotary

driers.

134

END VIEW.

SIDE VIEW.

SEMI-PORTABLE BITULITHIC PAVING PLANT. (PATENTED).

135

ROAD PRESERVATION AND DUST PREVENTION.

M. Dust-separator for reclaiming dust drawn by the exhaust fan
from the stone while it is drying.

N. Steel frame for supporting the mixing-platform, mixer, scale,
sectional hot-stone bin, and sectional screens.

O. Steel car on which the semi-portable or railroad plant is per-
manently set.

Cost. — The cost of bitulithic pavement varies with the
local prices of the materials, and with the local conditions.
It is usually $2 to $2.50 per square yard, exclusive of
grading and inclusive of guaranty. This high cost limits
its use to cities and parks, and prevents general use on
rural roads.

136

INDEX.

PAGE

ASPHALTOILENE — (see "Oil on roads; Petroleum") 58

ASSOCIATION —

Massachusetts Highway 8, 13

Roads, Improvement of, England 33, 35, 70

BITULITHIC PAVEMENT 16, 92, 100, 127-136

Address 134

Cost 136

Composition 127

Description 127

Extent 129

History , 129

Methods —

Base 130

Wearing Surface 131

Proportions 131

Mixing ; . . . 132

Rolling 132

Spreading 132

Testing 132

Opinions 128

Portable Plant 134

Summary 127

BROKEN STONE ROADS —

Calcium Chloride upon 18, 23

Coal-tar upon 16, 63, 65, 97

Appliances 87

Composition 86

Cost 83,87

History 69

Spraying machines 89

Sprinkling machine 88

Destruction 11, 13, 15, 0

Emulsions upon 25. jl

Existence 10, 11

Gladwell system 15, 111

Maintenance 11, 14

New Surface 82

Oil upon 37, 42-50

Penetration 69, 84

Sand rock-asphalt as binder for 126

Tar macadam 98

Cost 9D, 102, 103, 107

History 99

Methods 101, 107

Tarvia upon 74

Hot 76

Cold 77

137

INDEX.

PAGE

CALCIUM CHLORIDE 18-22

Characteristics 19

Cost 19

Methods 19

At Beverley, Mass 20

Cost 20

Good Effects 21

Improved 20

At Brookline, Mass 22

Conclusions 23

CLARE'S PATENT TAR COMPO 73

COAL-TAR ON ROADS 10, 15, 16, 63-120

Appliances 87

Heating 63,87, 102, 120

Steam coils 64-94

Spreading 88

Spraying 69, 89-97

Conditions for success 67

Failures 68; 71

History 69

Objections • 67

Opinions —

Aitken, Thomas 65

French engineers 65

Mass. Highway Commission 65

Page, Logan Waller 66

Ross, Charles W 84

Penetration 69, 84, 88

Preparations 74

Quality 71

Ductility 63, 71

Uniformity 64, 73

Variations 72

Spraying machines 15, 69, 89-97

Summary 63

Tarvia 73, 74

Address 73

Commendations —

Gladwell system Ill

Mass. Highway Com 73

U. S. Office Public Roads 73

Cold"B-"—

Cost 78

Spreading 77

Results 78

Hot "A"—

Cost 77

Covering 77

Heating 76

Spreading 76

Massachusetts roads 79

Boston park roads 80

Cost 80

Defects 81

Lynn 81

138

INDEX.

PAGE

Coal- tar on roads — (Continued} —

Cost 82

Crust 81

Methods 82

Results :.. 82

Newton —

Cost 83

Methods 83

Results 84

Wayland —

New surface 82

Penetration 69, 84, 88

Rhode Island roads —
Tiverton —

Costs 85

Methods 84

Results 85

Steep grade 85

United States Office of Public roads-
Experiments —

Composition 86

Conclusions 87

Methods 86

CLUB — Royal Automobile 70

COMMISSION — Massachusetts Highway 8, 11, 14

Royal 15

CONGRESS — International roads 16

DUST — Characteristics, 9; Danger from, 12; Nuisance, 11, 12; Pre-
vention 7, 11

EMULSIONS 24

Apulvite 31

Conclusions 34

Coudrogenit 30

Crempoid D 32

Dustoline 32

Cost 32

Effects 24-25

Ermenite 33

Hahnite 34

Mechanical 35

Cost 36

Method 35

Results 35

Methods 25

Boston park roads 25

Conclusions 27

Cost 26

Effects 27

Chicago park roads 27

Cost 28

Effects 28

Objections 24

Pine-oiline 31

Pulvicide 33

Rapidite 34

139

INDEX.

PAGE
Emulsions — (Continued') —

Sandisize 31

Cost 32

Summary 24

Terracolia 33

Westrumite 29

Characteristics 29

Conclusions 34

Cost 30-31

Methods

France 30

Germany 30

United States 31

Chicago 29

Limitations 31

St. Paul 31

EXPERIMENTS — Conclusions, 17; England, 15; France, 16; United

States, 16; Chicago parks , 27

GAS BY-PRODUCTS— (see " Oil on roads") 60

Coal-tar 10, 15, 16, 63-120

Creosote oil 43, 60, 62

Oil-gas tar 61, 62

Oil-tar 60

Tar-oil 60

Water-gas tar 35, 60, 86

GLADWELL SYSTEM 15, 111

MACADAM ROADS — (see "Broken stone roads") —

MOISTURE 18

Atmospheric —

Akonia 23

Calcium chloride 18-22

Fitzsimmons patent dust layer 23

Lymanite 23

Sea-water 18

Crust caused by 81

Water 18

Cost of 18, 21, 27, 43

MOTOR-CARS, EFFECTS OF 7, 10, 13, 14, 16

Race-track 14

MOTOR UNION 70

OIL, ON ROADS 37

Broken stone roads —
Arkansas —

Little Rock 48

Australia —

Sidney 44

Cost 44

Results 44

California 52, 56

Pasadena 47

England —

Liverpool 43, 62

Illinois —

Chicago 48

Massachusetts —

140

INDEX.

PAGE

Oil on roads — (Continued) —

Beverley 49

Precautions 49

Newton 50

New York 50

Cost 51

Rhode Island —

Barrington 47

Cost 47

Results 48

Cranston 42

Cost 42

Results 43

Tennessee —

Jackson 45

Costs 46

Heavy Residual 46

Light crude 45

Residual 45

Clay roads 51-55

Earth roads 52, 55

Failures 24-41-57

Gravel roads 56

Gas by-products 60

Composition 60, 86

Conclusions 62

Creosote oil 43-60-62

Odocreol 60

Oil-gas tar 61-62

Oil-tar 60

Tar-oil 60

Water-gas tar 35, 60

Composition 61-86

Methods 61

Gulf Refining Company, address 49

Objections 40-41

Petroleum 37

By-products 38

Distillation 38

History 41

Mazout 60

Residuum 38

Texas 57

Kentucky 58

Asphaltoilene 58

Address 58

Cost 58

Extent 59

Method 58-59

Asphaltine 59

Cost 60

Sources —

Borneo 38

California —

Adeline wells 38

141

INDEX.

PAGE
Oil on roads — (Continued) —

Asphaltic 41

Characteristics 38

History 41

Methods —

Clay 51-55

Earth 32, 55

Gravel 56

Repairs 57

Sand 41, 51, 52, 55

Stone 47, 52-56

Substitutes 52

Galicia 38-42, 60

Indian Territory 38-42

Kansas 28, 38-40-42, 52

Kentucky 38-40-42, 58

Louisiana 45

Ohio 37-42

Pennsylvania 37-42

Russia 37-42, 60

Texas 38-40, 43, 45, 47, 48, 49, 52, 57

Tests 38

Petrolithic roads 16, 51, 52

Address 54

Cost 51, 54

Method 51, 52

Oiling 53

Ploughing 53

Roller 16-54

Tamping 53

Rural roads —

Cost 55

Method 55

Sand roads 37,41,51,52,55

California 16, 41-51-52-55

Massachusetts 57

Cost 58

Method 58

Frost on 58

Michigan 17

Repairs 57

Screenings oiled —

Cost 50

Effects 50

Standard Oil Company 42

Address 50

White Sprinkler 51, 52, 76, 88

Address 88

PETROLITHIC ROADS 16, 51, 52

Address 54

Cost 51, 54

Method 51, 52

Oiling 53

Ploughing 53

142

INDEX.

PAGE

Petrolithic roads — (Continued} —

Roller 16, 54

Tamping 53

PETROLEUM — (see " Oil on roads") — By-products, 38; History, 41;'
Residuum, 37, 57-60; Sources, 38, 40, 52, 57; Tests 38

PREFACE 7

REFERENCES —

Adams, Arthur W 68

Aitken, Thomas 65, 89, 90

Arnaud, M 65

Blanchard, Arthur W 48, 84, 117

Bishop, Cortlandt F 14

Brown, Arthur 110

Conley, P. J 42

Ellery, N 55, 56

Fletcher, A. B 13

Foster, J. F 30

George-Powell, J 108

Gladwell, Arthur 15

Girardeau, M 65, 69

Heude, M 65, 95

Humphreys, H. Howard 115

Manning, Geo. W 114

McClintock, Wm. E 11

Owen, James 11

Page, Logan Waller 11, 45, 85, 87, 116, 123

Pettigrew, John A 26

Pillsbury, Franklin C 20, 78, 128

Poore, H. C 119, 120

Rablin, John R 80

Reichardt, Walter F 48, 122

Rose, John Colin 44

Ross, Charles W 50, 59, 83

Sigault, M 65

Sohier, Wm. D 13, 49

Tillson, Geo. W 128

Vahheur, M 65

Whyatt, H. G 101

Wike, Charles F 109

Publications referred to 8

ROCK-ASPHALT MACADAM 121

Methods-
City streets —

Arkansas, Little Rock —

Cost 123

Result 123

Rolling 123

Spreading 122

Suburban roads —

Kentucky, Bowling Green —

Cost "WTadsworth" Macadam 125

Description 123

Results 125

143

INDEX.

PAGE
Rock-asphalt macadam — (Continued} —

Rolling 124

Spreading 124

Sand-rock sheet asphalt —

Cost, Methods 126

Sand-rock asphalt for macadam binder 126

Sources 121

Summary 121

ROLLING TAMPER 16, 53, 54

SURFACE —

Perservation 7, 10, 41

Treatments 58

Calcium chloride 18

Coal-tar 63

Emulsions 24

Oils 37

Water 18

SLAG — Defects in, 104; Use of 104

TAR — (see "coal-tar on roads")

TARMAC, address \ . 104

Cost 106

Extent 105

History 104

Objections 104

Methods-
Birmingham —

Ettingshall 104

Gainsborough 106

Grimsby 106

Newark 104

Sheffield 105

Slag, defects in 104

TAR MACADAM 82, 98, 120

Canada —

Hamilton — cost 117

Ottawa — cost 117

Toronto — cost 117

England 82, 98, 115

Crushed stone —

Cost, comparative —

Gainsborough 103

Grimsby 101

London 109, 110

Manchester 108

Northumberland 108

Nottingham 102, 110

Sheffield 103, 109

Methods —

Hand labor 101

Cost 102

Machines 100, 102, 103

Cost 102, 103

Results 99, 108, 110

Steep-grade 85, 110

Gladwell system 15, 98, 99, 111, 116

144

INDEX.

PAGE
Tar macadam — (Continued) —

Cost 114, 115

History Ill

Method 112

Finishing 114

Rolling : 113

Spreading 112

Tarring 112

Thickness 114

Opinions 115

Cost, Comparative 99

Failures 110

History 99

Summary'. 115

United States—

Massachusetts —

Estimates 119

Kettles 120

Rhode Island —
Charlestown —

Cost 118

Methods 117

Narragansett Pier —

Methods 118

Varieties i . . . 98

TAR-PAINTING 72, 92, 98

TAR-SPRAYING MACHINES 15, 69, 89, 97

Aitken's 89

Address 89

Cost 91

Details 90

Method 90

Results 92

Rolling 90

Spraying —

New Macadam 90

Cost in England 91

Cost in United States 91

Old Macadam 92

Cost 93

Conclusions 97

Lassai ly — Johnston 94

Co t 95

Details 94

Good r suits —

In England 95

In France 95

Tarmaciser —

Address 97

Details 97

Tarspra —

Address , 93

Details 93

Number in use 93

Results 93

145

INDEX.

PAGE
Tar-spraying machines — (Continued} —

Thwaite 96

Cost 96

Details 96

TARVIA — (see "Coal-tar on roads") 73, 74

Commendations 73. Ill

Cold"B" 77

Hot "A" 76

Massachusetts roads 79

WADSWORTH Rock-asphalt macadam 51, 125

WESTRUMITE — (see "Emulsions") 29

WHITE SPRINKLER 51, 52, 76, 78

146

THIS BOOK IS DUE ON THE LAST DATE

STAMPED BELOW
AN INITIAL FINE OF 25 CFNTQ

20 1933
21 193 }
APR 131938

LD 21-50m-l,'33

s 13290

UNIVERSITY OF CALIFORNIA LIBRARY