Catoctin clarion., 1917-08-30
EARTH ROAD GRADE
Stability of Entertainments Is of
Great Importance.
CAREFUL SCRUTINY IS URGED
To Prevent Damage by Shrinkage Ma
terIaI Used Must Be Free From
Vegetable Matter and Uni.
formly Compaeted.

prepared by the United States Depart
ment OF AgricultureD
One of the most important cOnSid-
erations connected with the grading of
an earth road is the stability of the
embankments. Where road is situ-
ated In cut and is well drained it is
not likely to be affected seriously by
such agencies as shrinkage. settlement,
and slipping, any one of which may in
jure or destroy road situated on
poorly constructed embankment. In
grading a road, therefore, the methods
employed in building the embankmentS
are deserving of much more careful
scrutiny than those employed in MAX
ing excavations.
To prevent road over an emhank-
ment from being damaged by shrink
age of the material forming the en-
bankment, the material must be free
from vegetable matter and uniformly
compacted as it is deposited. Where
the road surface is to be of earth, the
embankment usually may be compact
ed sufficiently to prevent injury from
shrinkage by spreading the material In
relatively thin horizontal layers and
letting each layer be compacted by the
grading teams as the succeeding layer
is being spread. Layers of ordinary
earth, not more than - inches thick,
can be compacted fairly well in this
way, provided that the grading teams
are made to travel over the entire sur
face of each layer, and that the mate
rial Is spread uniformly. Where the
road surface is to he of some highly
improved type, each layer of the en-
bankment should be rolled thoroughly
with a power roller weighing not less
than about ten tons.
Settlement of embankmentS, aside
from that due to shrinkage, may be
caused by the gradual tlattening of the
slopes or by lack of stability Of the
ground surface over which the embank-
ment Is constructed. The question of
ground surface stability usually does
not arise as a grading problem except
where an embankment is being con
structed over very marshy land. If
proper precautions are not observed,
the embankment material may be alb
sorbed gradually by the marsh until
the entire roadbed has disappeared, an
occurrence which is not infrequent.
Where drainage of the marsh is i'm
practicable, the lower portion of the
embankment, which would come in con-
tact with the marsh water should be
formed of some nonslaking material
that will cement together and dis
tribute the weight of the embankment
over the entire bottom area. Some
varieties of gravelly clay are excel
lent for this purpose. Where the
marshy matter Is very soft and deep,
1t may be necessary to lay a wide
foundation bed of logs, or fascines,
upon which to construct the embank-
ment, but such foundation bed would
not obviate the necessity for using
nonslaking material in the lower por-
ton Of the embankment.
Where embankments are constructed
on very sloping ground, or where old
embankments are to be widened, there
always Is a tendency for the new mate
rial to slip along the plane of separa-
ton. In such cases the old surface
should be roughened before the new
material is deposited. Where the old
surface Is earth, it usually can be
rOughened sufficiently by plowing a
series of rather deep furrows about
two feet apart. Old rock surfaces or.
dinarily are fairly rough to begin with,
but to prevent slipping it may be neces-
sary in some cases to blast steps into
such surfaces before depositing EN-.
bankment material.
No matter how the grading Of an
earth road may be accomplished 1t
usually Is economical to bring the road
surface to Its final shape by means Of