Montgomery County sentinel., 1891-05-01
How to Make Good Roads.

A correspondent of the Washington Star
gives the following in regard to the proper
construction of roads in the District Of Co
lumbia:
1t is well known that the soil OF this part
of the United States contains so much clay
that the unmacadamized or "dirt roads" as
they are generally called, become almost i'm
passable in seasons of long continued rain.
The clayey subsoil does not allow the water
to drain off, and the passage of vehicles over
the mixture of clay and standing water after
a time makes a sticky mixture, a sort of
mud pie, whose depth increases with the
amount of travel. The properly macadam-
ized road consists of foundation OF broken
stone, coarser at the bottom and finer on
the surface, which, when properly settled
and rolled down, forms natural concrete
arch across the roadway, through which sur
face water drains and which affords smooth
surface TO drive upon, alike free from mud in
wet weather and dust in dry times, and which,
if properly mended, will last indefinitely.
Most of the District roads have such a foun-
dation, and when this has been made, as in
the case of the Conduit and other roads, of
broken quartz and as mended with the same
material finely broken it produces road
way that cannot be excelled. The gneiss,
of which great quantities are lying at hand
at the mouths of the various openings
through which our two million dollar tun-
mel was excavated, is a good material for
foundations, and when dressed with broken
quartz makes an almost equally good road +,
but when used alone grinds up into clayey
material that is both muddy and dusty
Watever stone is used, however, it is essen
tial that it should be in broken angular
fragments of fairly uniform size. Rounded
water worn stones will never pack, and If
the fragments are of unequal size the larger
stones project above the surface as the rest
of the road settles down and cause jOlting
and even serious injury to vehicles passing
over them. Soil and clayey gravel are the
worst materials that can be used for road
making and dressing.
The present mending Of our Districtroads,
as far as my observations show, is conducted
after two methods. One consists in spread
ing loosely coating of broken stone Of un-
equal size, often large enough to constitute
a kind of rip-rap and leaving It without
rolling or top dressing for passing vehicles
to wear down. This method is cruel 10
horses destructive to fine vehicles and re-
suits finally in leaving the road surface more
uneven than it was before the dressing.
| This would have been avoided by proper
rolling and settling, and the final expense
of the District would have been less, to say
nothing of the destructive wear 10 vehicles
obliged to pass over it.
The second and most general method ol
mending is the spreading of several inches
of very clayey gravel loosely over the sur.
| face OF the road. This is the cheap method
employed on county roads, which is only a
shade better than mending with soil alone
and makes only 0 temporary improvement
The rounded stones in the gravel never
pack, the clayey material in dry times be-
comes fine impalpable dust, and in we
weather, if there is any considerable travel
over the road, makes sticky mud pie ex
tending down to the stone foundation. The
| defects of this method have been abu ndantly
illustrated during the past winter, when the
heavy teams carrying material for the vari
Gus suburban improvements have "pugged
this superficial dressing of clayey gravel int,
a mass Of plastic and sometimes liquid mud
nearly knee deep.