Atlanta semi-weekly journal. (Atlanta, Ga.) 1898-1920, 1911-02-21

Water should never be permitted to
remain under macadam road. 1t soft
ems the foundation so that the broken
stone is forced dowrNinto 1t by the wheels
of vehicles. thus causing ruts to develop
In the macadafn. In freezing it expands
and theaves'' the broken stone, destroy
ing the bond and causing the larger frag-
ments of stone to rise to the surface. As
a result the material in the subgrade is
forced up into the interstices. and in the
spring the macadam will be found to be
rough. irregular in shape. and weak
cned There are several ways of remov-
ing the subsurface water, at least in part.
Sometimes if the grade is raised in wet
places the trouble will be lessened, par
ticularly If porous materials are used.
Side drains may be constructed in the
cuts on each side Of the road, just out
side of the limits of the macadam.
These drains consist of narrow trenches,
filled with broken stone or small gravel
stones, with pipe five or six inches in
cliameter near the bottom. The pipe is
laid with open joints, true TO grade, and
is carried to a roper outlet Sometimes
the pipe Is omitted and the entire trench
is filled with stones in which case. it is
called a blind drain, Such drains serve
to cut off the subsurface water before it
can get under the macadam.
The subgrade may be excavated to the
width of the smacadam so as to be six
to eight inches deep at the edges, and II
to IS inches deep at the center. The sur
face will then have the shape of an ex-
tremely fiattened letter V. The bottom
should be fairly true to grade, so as to
permit the water to flow readily This
excavation is filled with stones varying
In size from small pebbles to boulders
eight or ten inches in diameter, the larg-
est being placed at the bottom. These
stones need not be placed with special
care, but the condition of the mass should
be such as to permit consolidation with
a roller. To dispose of the water collect
ed by a drain of this kind, narrow
trenches should be cut ITO the sides so as
TO connect with open outlets. These
trenches should also be filled with stones.
Such drain is usually effective and or
dinarilyf costs less than two side drains.
a Another way OF multiplying in part the
effect OF the subsurface water is to con-
sfruct foaindatipn Of telford. Former
liz. nearly all macadam roads we're built
with a tcIford base regardless of any
consideration or the requirements of
traffic. 1t is now generally recognized
that, except in unusual cases where the
subsoii is full of water which can not
be drained out the telford base is UNI
necessary except Tor purposes OF SUD-
drainage A satisfactory telford foun-
dalton may be made by placing verti-
cally ON layer of gravel two or more
inches in depth, stones of fairly uniform
size, not exceeding ten inches in width.
six inches in depth, and varying in
length from six to 20 inches. The stones
should be set on their broadcast edges.
lengthwise across the road, and wedged
rfgidly into position by driving smaller
stones(into the interstices with mauls.
Projecting points should be broken off
with stone hammers, depressions filled
with %chips. and the telford rolled with
steam roller until it is true to the
desired cross section.
Where the foundation of the road
would otherwise be very bad, and no
gravel or other like material is readily
obtainable, or where an unusually sub