Frostburg mining journal. [volume] (Frostburg, Md.) 1871-1913, 1899-04-29
PENNSYLVANIA ROADS.
How Highways Are Constructed In
Allegheny County.

Allegheny County.
The highways of Allegheny county
are supervised by practical engineer
of wide experience, f. w. Patterson,
and the method of construction is de-
scribed i'll the Pittsburg Press.
The transforming of the bad roads of
this mountainous county into good ones
was begun in September, 1897, and as
a result Is miles are completed and in
use, and about 20 miles are now in
course of construction. The traveller or
casual observer passing over one of these
new roads has little idea of the amount
of material and labor required to pro-
duCe the hard, smooth surface and the
easy grade.
The method of construction adopted
for these roads is what is known as mac
adamiZing, that system Of building be-
ing best adapted to the highways of
this county. The surface Of the road
does not indicate its substantial quail
ties, as it is much like any smooth road
would appear under favorable Circum-
stances, except that it is carefully
crowned in the center and rounds so
nicely into the clay road on either side
that were it not for the difference in the
color it would ne difficult to tell Just
where the macadamized portion began.
This statement is applicable only when
the clay portion is at its best, neither
rough, muddy nor dusty. 1t is under
unfavorable circumstances that the
macadamiZed road stands pre-eminent
Continued wet weather does not affect
it i'll the least, and long drought only
produces thin blue dust on the surface
caused by the grinding Of the ligonier
screenings under the wheels of passing
vehicles.
The standard construction adopted for
the Allegheny county roads is as fol-
lows: After the road has been graded,
slOped and guttered au excavation is
made in the center IA feet wide and
sufficiently deep to bring the surface
when completed IS inches above the
surface of the cutters, to provide a
crown, in order that the water may be
shed rapidly. The bottom of this exca-
walton is then rolled with a ten ton
steam roller. Eight inches of native
stone, broken to 31a inches in diane
ter, is filled in and the roller again APP
piled. If the ground be low or soft, tel
ford foundation is substituted for the
broken stones. On this is layer of
ligonier stone, crushed to 219 inches in
diameter, which is also rolled. Then
comes another layer Of the same mate
rial, but of smaller size, l = inches
thick, which serves to key the larger
stone. The roller is again brought into
requisitiOn.
The whole is finished with a layer of
fine ligOnier screenings, which fill the
interstices and form smooth surface.
This is wet and rolled firm. When used
for time, it becomes so hard that it is
almost like concrete. The road engineers
adopted the foregoing as the standard
construction for all the country roads
improved after careful study of the
methods employed by road builders both
in this country and abroad. The 1E
miles of road now completed have cost
the country on all average SIP, 600 pei
mile, which, when the enormous cuts
and fills made necessary to reduce the
grade in many places are considered, il
not excessive. The cost of grading alone
has averaged nearly So, 600 mile.
This, of course, varies according to the
physical and typographical character OF
the country through which the road
passes,