Semi-weekly herald., 1913-04-17

ten-ton roller This foundation
course is placed on a thoroughly roll
ed subgrade. On top of the six-inch
course of field stone is placed three
inches of surfacing material, consist
ing of broken stone with bituminous
binder.
For the most part of the stretch
that type of road will, or ought to,
last for years. permanently, if kept
properly surfaced. The subgrade IS
sand and gravel, and neither heaves
with frost nor breaks in thaw. The
foundation course will settle into the
gravelly sand and become as solid as
the earth itself. And that of soil
drains itself.
But at frequent intervals there juts
out from the adjacent hills projec-
tions of different formations. One
may be of hardpan; another of clay;
still another of alluvial deposits; and
some ledges of loose rock probably
semi -disintegrated limestone. These
outings may be anywhere from fifty
to five hundred feet wide where they
cross the right of way Sometimes
on account of the narrowness of the
valley or the passage of the river close
to the hill, it is necessary to exca-
vate the hillside, possibly building
retaining wall TO establish such road
way as is required under the New
York law, with fifteen feet of metal
ing and four and a half feet of shoul-
der and a three-foot ditch on each
side.
While a New York road is taken as
an illustra tion, because of the vast
amount of construction under way at
the present time, the same principle
where road building is going on. New
York has no monopoly of the idea of
Standardization" in making roads.
Why does it not occur TO the engi-
and prepare the plans, to except from
the general foundation plan those
stretches which require different
treatment? The veriest tyro in the
road-building business should know
that the standard, as applied to the
sand and gravel subgrade, will not be
successful when applied to other soils
There must be carefully studied sys-
TENS of underdrainage, to lower the
level of the bench-water e a point
below the frost line; or back drainage,
to prevent seepage of moisture into
the road foundation; or such other
treatment as the condition may re-
quire, even if the stretch of road be
not more than two rods in length. Be
sides, under any such conditions the
field stone foundation course should
give place to a solid course of evenly
broken stone, rolled down, sanded or
filled with stone dust, flushed, and
rolled some more, so as to make
foundation worthy a good road.
The one thing that may be stand
ardized is the surface. Under present
conditions of traffic the standards of
today are likely to be obsolete tomor-
row, even as the water bound maca-
dam road, the standard for century
or more, has virtually passed out of
consideration in new construction
About the only materials available
for road surfacing under present con-
ditions are vitrified brick, broken
stone with binder of bitumen of
some sort, and Portland cement con-
crete. By reason of the limited de-
posits of clay, which will make good
road brick, and the expense of freights
the use of vitrifed brick is confined
to limited areas. Wherever it can
be used economically brick makes "a
most excellent road surface. 1t is
dustless, smooth, and when properly
laid, durable. 1t costs, according to
the figures prepared by the National
Paving Brick Manufacturers associa-
ton, approximately one thousand dol
lars per mile per foot of width, where
the expense of grading is normal and
the freight not excessive. This cost
includes the grade and a fve-inch
concrete foundation.
Different surfaces, made of broken
stone and bituminous material, are as
plentiful as are makers of surfacing
specifications. Numerous preparations
add variety to the collection. Most
of them, patented and otherwise, make
serviceable roads within the limits of
their availability.
Concrete of Portland cement with
sand and either broken stone or care
fully selected gravel as mineral ag-
gregate, is attracting much attention.
Wayne county, Michigan, has put
down a large mileage of concrete
roads during the past four years, and
the officials express themselves as
entirely pleased and satisfied with the
results. Recently plan of putting
on the concrete a surfacing, or mat,
of bituminous material mixed with
coarse sand or fine gravel has been
adopted. This method has become
sufficiently recognized so that it has
been adopted for a large portion of
the California state hiuhwav s,yctap,