The farmer and mechanic. [volume] (Raleigh, N.C.) 18??-19??, 1911-01-17
DRAINING COUNTRY ROADS
Properly Built Macadam Roads Are Supplied With a Drain TO
Garry Off Surplus Water
BY A. 3. FLETCHER

by the wheels of vehicles, thus cauS-
ing ruts to develop in the macadam
In freezing it expands and heafeS
the broken stone, destroying the bono
and causing the larger fragments OF
stone to rise to the surface. AS a re-
suit 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
weakened. There are several ways
of removing the ~subsurface water, at
least in part Sometimes if the grade
is raised in wet places the trouble
will be lessened, particularly it porous
materials are used.
Side drains may be constructed n
the cuts on each side Of the road,
just outside of the limits of the maca-
dam. These drains consist of mar
row trenches, filled with broken stone
or small gravel stones. with a pipe .
or 6 inches in diameter near the bot
tom. The pipe is laid with open
joints. rue TO grade, and is carried
to a proper outlet sometimes the
pipe is omitted and the entire
trench is filed 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 e~xcayated to
the width of the n1acadam SO as TO
De U 10 . lE1lcS uccp dit the euScS,
and Il to Is inches deep at the CEN
ter. The surface will then have the
shape OF an extremely hattened let
ter Y. The bottom should be fairly
true to grade, SO as to permit the
water to flow readily. This excava-
ton is filled with stones varying in
size from small pebbles to bouiders 8
OF 10 inches in diameter, the largest
being placed at the bottom. These
stones need not be placed with special
care, but the condition of the mass
should be such a sto permit c%onsoli-
tlation with a roller. To dispose Of
the water collected by a drain OF this
kind, narrow trenches should be cut to
$ the sides SO as to connect with pen
outlets. These trenches should also
- be filled with stones. Such a drain is
usually effective and ordinarily costs
less than two side drains.
Another way OF multiplying in part
the effect Of the subsurface water is
to construct q foundation of telfOrd.
Formerly, nearly all macadam roads
were built with q telford base, re-
gardiess of any consideration Of the
requirements of traffic. 1t is now
generally recognized that, except in
unusual cases where the subsoil is
full of water which cannot be drained
out, the telford base is unnecessary
except for Of subdrainage.
A satisfactory telford foundation may
ne Hldue ny pidcluS tcTt1cdifE on q
layer of gravel 2 or NOR einches in
depth, stones Of fairl yuniforn1 size,
not exceeding 10 inches in width, s
inches in depth, and varying in length
from 6 to 20 inches. The stones
should be set on their broadest edges,
lengthWise across the road. and
wedged rigidly into position by driv-
ing Smaller stones into the interstices
with mauis, Projecting points should
be broken off with stone hammers, de-
pressions filled with chips, and the
telford rolled with a steam roller until
1t is true to the desired cross sec
ton.
Where the foundation of the road
would otherwise be very bad. and
no gravel or other like material is
readily obtainable, or where an un-
usually substantial road is required to
meet the demands of traffic, this
form Of construction is. recommended.
Under ordinary conditions it is much
too expensive. It has been said, and
there is some supporting evidence,
that a rigid and unyielding telford
base has the effect Of an anvil. and
that the acadia under the pound
of traffic. wears more apidl thar
In the ordinary broken-stone road.
Several other devices are some
times employed to take care OF the
subsurface water, such as the center
box drain. built OF slabs Of stone, and
SIDE drains. with plank boxes in lie,
OF drain tile. Usually these are either
too expensive or too unstable a nature
to be recommended.
Every macadan road should he
crowned, in order that the water
falling upon it may run quickly to
the cutters. It is also necessary that
the shoulders should have the same
slope as the macadam or h q
little greater.
For a road Is feet or less in width
it will be found satisfactory to havp
the center ) 1-2 inches higher than
the sides, forming a crown Of three
quarters Of an inch TO the foot. On
roads OF greater width it will be neees-