The Hartford republican. (Hartford, Ky.) 18??-1926, 1908-05-15
effects or SPEED
ing AUTOMOBILES.
Autos Speed at a mile a
Minute TO Prove
That Rubber Tired Vehicles Strip
the Roads of Surface
Binder.

Ing at something III excess OF inlle q
minute, while an impenetrable cloud
of fog-grty rosa uu lung TO the no.
rizon and marked ne spoSdlag course
of the big machine, was t.-e sight
witnessed by travellers on the famJus
conduit road dozen miles from Wash
ington on Thursday, April %.
The seemingly pronounced violation
of the speed ordinances was counte-
nanced by two of the Nations feder-
al departments; Agriculture and War;
however, the rushing motor-car having
been pressed into requisition by l.. w.
Page, Director of the office of Public
Roads, and DR.. Allerton S. Cushman,
determine the effects of Automobile
traffic upon macadam highways, and
the stretch of thoroughfare was plac-
ed at their disposal by War Depart
ment officials.
While the racing car and others of
various weights and types made many
trips over the selected stretch of a
mile and a half at varing rates of
speed, from to IS miles an hour, a
corps of skilled photographers, equipp-
ed with the most modern devices for
photographing vehicles at very high
speeds, made accurate records of the
various tests.
1t has long been known to highway
engineers that automobiles were rapid
ly shortening the lives of the rock
surface roads of the world, and many
experiments have been made in the
past six or seven years to determine
the actual cause of the damage done.
To understand how the soft broad tires
of the modern moter car can work an
injury to a surface that not only with
stands, but improves under the con-
slant passing and replacing of We
hicles with iron tires, one must be
apprised briefly of the theory on which
first Tresauget of Limoges and latter
MacAdam of Ayr, worked when CIV
ing such highways TO the world. They
reasoned that a road surfaced with
bits of stone would improve under
wagon traffic because the iron tires
of the passing vehicles would constant
ly crush the stone andform rock dust
particles; that those rock dust parti-
cles would not merely fill in all the ir
terstices between the stones but would
also form a surface dust binder; the
wettings and rollings tending TO
cement the dust into a shell like sur
face and thus make the entire road
one Notwithstanding, watershed
ding mass.
They reasoned well and wisely. The
macadam roads lived up TO the the
cries of their inventors and improved
with the passing years until the ad-
vent of the automobile. 1t was but
a short time after it came into vogue
that highway engineers in all civilized
lands learned that a new condition wa.
confronting them and that establish
ed customs were being menaced. The
trouble was quickly traced to the au-
tomobile and it was studied. 1t was
soon noted that the soft rubber tire
was the highway menace. 1t crush
ed no rock itself and therefore con-
tributed no quota of the needful sur
face dust binder, while the remen-
dous tractive force of the rear wheels
drew up the dust made by the iron
tired wagons and sent it whirling ava
over adjacent lands.
Those who witnessed the expert
ments of Thursday near the National
Capital could not doubt for moment
that the various road experts all over
the world are correct in the opinion
that very rapidly driven automobiles
are rapidly tearing up the surface Of
the macadam road, for not only were
huge clouds of dust lifted into the
air and blown off the road, but care
full examination showed that the ma
terial under the wheel tracks Of the
machine was distinctly loosened and
travelled even during the short period
Of these tests.
No such effects were noticeable
after the passing of iron tired vehicles
the series of tests beginning with the
passing of a horse drawn vehicle.
This was photographed as it moved
along and also the wagon tires pass
ed a given mark. Then the automo-
biles were sent over the course. The
first was a heavy weight touring car
moving at five miles an hour. A
series Of pictures was made Of that
car on it's many journeys at varying
rates of speed until its maximum
of As miles an hour was attained.
Then the work was taken up by the
huge racer, which tore down the road
first at a speed of so miles an hour
then at So, go, and finally at ga. 1t
fairly lifted the road surfacing mater
ial as it sped along, regular ridges of
rock dust rising in front Of the rear