565 PARK AND CEMETERY. 
METHODS OF BITUMINOUS ROAD CONSTRUCTION 
Address Before American Road Builders’ Association by Harold 
Parker, Chairman State Highway Commission of Massachusetts. 
I am happy to inform you that the 
governor of Massachusetts has officially 
appointed me a delegate to this conven- 
tion. This will indicate to you that the 
state of Massachusetts not only is 
ready and anxious to learn from others, 
but to convey, to any who may desire, 
such information and knowledge as it 
has acquired by experience in the con- 
struction and maintenance of public 
highways. 
It also gives me great pleasure to bear 
testimony of the progress that has been 
made in this highly important work dur- 
ing the years that have elaspsed since 
the first convention of this organization. 
I have a distinct recollection of the 
speeches to which I listened at early 
meetings of this association, and it is 
interesting to compare what was said at 
those meetings with what is being said 
here today. During these years not 
only has the interest in scientific road- 
building been vastly increased, but a 
new consideration of the matter has been 
forced upon us by the advent of the 
automobile. 
Not many years have elapsed since 
the real interest in this subject was gen- 
erally apparent in America. We, in 
Massachusetts, perhaps felt the pressure 
before it was felt in the middle west, or 
in any other part of the United States, 
and we got to work, by the organization 
of the highway commission, among the 
first of all the states, and have been 
building, maintaining and experimenting 
with highways under all possible con- 
ditions ever since. 
Our representatives have investigated 
methods employed not only on this con- 
tinent, but in the main countries of 
Europe, so that it may be assumed that 
we have a very good conception of the 
comparative conditions everywhere ; and 
it is possible for us, therefore, to advise 
you on two points : First, as to the 
general progress made in this most im- 
portant work ; and second, as to the 
methods best adapted to the preservation 
of roads against the destructive elements 
of automobile travel. 
I believe that it is becoming generally 
recognized that the amateur or the poli- 
tician, as such, is not properly an ad- 
visor or administrator either as to the 
construction or method of maintenance 
of public roads. It is eminently a mat- 
ter where only the most skillful and ex- 
fjcr'enced have any right to direct. Prob- 
ably more money has been wasted by 
incompetent and inexperienced men in a 
futile effort to improve roads than in 
any other one work where public money 
is expended. 
If this view is still further extended 
to the point where the entire public in- 
sists upon having only proper men en- 
gaged in this work, a most important 
step will have been taken. Such men 
will, of their own initiative, watch the 
experiments and progress of other road 
builders, as well as learn from their own 
experiments, and evolve methods which 
will in the most satisfactory way solve 
the problems arising from the conditions 
under which they themselves labor. 
The second point to which I wish to 
call your attention is the methods that 
have been adopted generally for pro- 
tection against motor traffic; that is, 
traffic which is swift-moving, constant, 
and in which the motive power is trans- 
mitted through the wheels, and not con- 
tained in the animal drawn vehicle. The 
effect produced by this traffic is, of 
course, manifest to everyone who has 
had any exerience with roads. The wide 
pneumatic tire of the automobile, pass- 
ing swiftly over the road, and propelled 
by the friction of the wheel upon the 
road surface, inevitably draws out the 
finer binding constituents of the road, 
sweeps them away by the swift passage 
of the vehicle, and finally loosens the 
larger parts, so that a road not care- 
fully tended and not provided with any 
other binder than stone dust and water 
will, in a very short time (proportional 
to the number and speed of automobiles, 
of course), be entirely disintegrated and 
destroyed. 
To overcome this disintegration, road 
builders all over the world have used 
every effort of science, skill and experi- 
ment. Tar distilled to varied degrees 
of refinement, residuum and asphaltic 
oils, and asphalt have been used in 
every way that ingenuity could suggest. 
The method of applying these differ- 
ent bituminous products, is, perhaps, as 
important a feature as the material it- 
self. It has been found necessary to 
determine by experiment what, if any, 
penetration there was of any of these 
materials into the surface of the road 
to be treated. It has also been neces- 
sary to determine by experiment the 
depth to which these ingredients should 
extend in order to reserve the road sur- 
face. 
Several years ago I heard of the 
Aitkin spraying machine, which was 
used in England for spraying refined 
tar under considerable air pressure. It 
had previously seemed to me that, to 
make a surface application sufficient, the 
way to apply it was by forcing the ma- 
terial onto the road, in different layers, 
under high pressure. I therefore looked 
up and examined with great interest this 
machine when I went to England two 
years ago. I found that it was serving 
the purpose of protecting suburban and 
country roads with Tarvia in a highly 
satisfactory way, and that many hun- 
dreds of miles of road about London 
and in the so-called provinces had been 
treated in this manner. Two of these 
machines were imported and put into 
use on our roads in Massachusetts, and 
have well borne out my views in re- 
gard to them. 
We find, after trying the different 
methods known as mixing, grouting, 
penetration, and different kinds of sur- 
face treatment, that where a road has 
once been well built with macadam or a 
good quality of gravel and asphaltic oil 
of suitable quality and consistency, ap- 
plied under a pressure of from seventy 
to one hundred pounds to the square 
inch, in layers of a quarter of a gallon 
to the square yard, and this immediately 
covered with stone chips, clean sand or 
gravel, and rolled with a ten-ton roller, 
a result is produced which, for any but 
exceedingly heavily used roads, will pre- 
serve and maintain the surface for two 
years or more, according to the number 
of applications that are made. The spec- 
ifications for asphaltic oil used by the 
Massachusetts Highway Commission 
for the present year are as follows : 
ASPHALTIC OIL. 
The oil submitted shall be of uniform 
color, appearance, general character and 
viscosity and must fulfill the following re- 
quirements : 
(a) It shall not froth when heated to 
100° C. 
(b) It shall have a specific gravity of at 
least 0.97. 
(c) It shall not contain more than 0.5 per 
cent of dirt or adventitious mineral matter. 
(d) It shall contain not more than 1 per 
cent of matter insoluble in carbon bisul- 
phide. 
(e) It shall be of such viscosity that 60 
c.c. measured at room temperature (78° F. 
or 26° C.) shall when at 100° C. be not less 
than 250 seconds nor more than 500 seconds 
in passing the Lawrence viscosimeter or 
200 c.c. measured and tested at the same 
temperatures shall be not less than 900 sec- 
onds nor more than 1,800 seconds in pass- 
ing the Bngler viscosimeter. 
(f) When 20 grams are heated in a flat 
bottom dish 3 inches in diameter for twenty- 
one hours in a well ventilated oven, kept at 
a temperature of 250° C., the loss in weight 
shall not be greater than 15 per cent. 
(g) When subjected to a number of heat- 
ings at 250° c. in a well ventilated oven 
with intermediate separations of asphaltene 
and of matter insoluble in carbon bisulphide 
until the final petroleum ether extract is 
not more than 10 per cent by weight of the 
( Continued on page XII) 
