The county record. [volume] (Kingstree, S.C.) 1885-1975, 1902-10-09

NJ first, Whlcn mas d tenuehcy
- to fatten out the road and
destroy the proper cross slope grade.
When the finished road has been tested
by the engineer and found deficient
along the entire line, only one of two
courses is open to the engineer to bring
the road up to the established grade
either to disturb the entire surface or
to put on an additional quantity of
| screenings. 1t is seldom that the first
course is resorted to, but too frequetly
the latter. A road brought up in this
way with screenings will always be an
object of great solicitude and an ex-
pensive road to keep in good repair.
The practice of centre rolling has a
tendency also to leave the outer edges
and three or four feet Of the macadam
very loose in their construction, While
The centre. when the road is first turned
over for travel, is the best part of the
road for use, which by use In a short
time breaks its bond and works out
| toward the sides, and then trouble coIn-
mences. In building macadam or any
| other pavement there are no little
things, from the blowing up of the road
to the last rolling the road receives.
| Very much depends even upon the
| camping of the load Of metal In the
roadbed. Under no consideration what
ever should a load Of stone be allowed
to be dumped on the roadbed proper,
unless every part Of the load, before
rolling, is removed and placed with
| shovels in the place it is to occupy,
! for the simple reason that, when dump
ing is resorted to, whether from a cart
or from a reach wagon, uniform roller
pressure cannot be had upon all parts.
The part which is brought to the es-
tablished grade by shovels will respond
to the rolling, but where the body Of
the stone fell there will be resistance,
which in time will develop a weakness
in the road. Every part of the road
should receive equally the same amount
Of roller pressure.
He has used telford only in special
cases where the foundation was uncer-
tain. A ~thirteen-inch telford road will
not wear as we'll as 4 seven-inch ma
cadam road upon q gravel or mixed
earth or sand foundation. The rigidity
of the t~hirteen-inch pavement con-
duces to the destruction OF the road,
while the elasticity of the foundation
of a seven-inch macadam tends to its
preservation; so he has not extended
the system Of telford reads any further
than was absolutely necessary, pre-
ferring to use good sub-grade material.
with plenty Of rolling, and to extend
his system of macadam at a less price
than If the roads had been Of telford
construction.
If q macadam road is properly built
there is no necessity for the application
of screenings in maintaining the road.
Screenings placed upon an old ma
cadam road must lie upon the surface,
where in dry weather it is dust and in
wet weather it is mud. The time to re-
pair Il macadam road is when the
stones begin to show bare. when the
screenings or wearing surface of the
road has been lost. Then. instead Of
screenings, stone ranging in size from
one-half inch to three fourths inch,
longest diameter, should be used. If
upon the surface Of the road, over the
full width Of the travelled part and to
the depth of about three-fourths Of an
inch (no greater depth should be ap-
plied). they will not need water or
rolling. The point Of contact will be so
near the point Of resistance that the
full crushing force Of the hoof or the
weight Of the load upon the wheel will
fracture the stone. The fracture will
yield just a small amount of dust. or
detritus, which falls quickly to the
under surface and is protected from the
heat Of the sun, so that it will not dry
out, and from the wind, so that it
cannot blow off. In a very short time,
the ordinary travel will reduce all this,
Of course, and a gradual healing pro-
cess will 60 on over the entire surface.
He has tried this method in Connect
cut, and has not found a single failure.
1t yields a very large return for the
money invested. If a road has broken
up-which condition, however. should
not be allowed to occur-there Is only
one thing to do, and that is to apply
whatever stone is necessary and, Of
course, go through the process Of
screening, wetting and rolling.-Ab-
stract of a paper'by j. H. Macdonald.
Highway Commissioner of Connecti-
cut.