Frostburg mining journal. [volume] (Frostburg, Md.) 1871-1913, 1908-08-22

SHOWING HOW GRAVEL IS SOON DEPOSITED
AT FOOT OF HILL WHEN PLACED ON
STEEP GRADES.
the road before the gravel is placed
upon it considerable Improvement may
be made on almost any of the roads
where gravel is Obtanable, as ii makes
an even, hard and firm roadbcd when
supported by proper foundations. An
example of the better constructed
gravel roads is that extending from
Marlboro to Washington, which was
built originally as a toll road.
An economical form of construction
is to use the gravel as Il support for Il
macadam surface where the travel over
any particular thoroughfare would
warrant such an Improvement The
crown or transverse slope of road
should only be sufficient to carry the
surface water to the cutters. On dirt
roads where ruts are easily formed
the slope needs to be more than on
macadamiZed surface, but never sufil,
cient to cause Inconvenience to travel.
One inch to the foot or seven and
half inches on a fifteen foot road will
be found about right. \ good macadam
road does not ordinarily need so much
crown, depending on the grades. On
grades up to and including four feet
per hundred one-half inch to the foot
IS Suticient from four to and includ-
ing six feet per hundred three-quarters
of an inch should be allowed. \ trans
verse slope of more than one inch per
foot gives too much list to wagon
when at one side. The advantage of aS
fiat Il road as possible IS the leSSeninS
of the tendency for the travel to keep
to the center of the road and the con
seQuent avoidance of the formation of
rutS and a horse path
There are many counties In Mary
land where gravel of excellent quality
is abundant and where at the same
time there is very little stone that Is
fit for road construction. The gravel,
however, properly applied will max"
most excellent roads, far superior to
any earth road and. while not possess
ing the wearing qualities of hard. bro
ken stone, will answer sufficiently well
for those country roads that have com
paratively light traffic. On roads hay
ing very heavy traffic it will be found
in the long run to he cheaper even at
very much greater first cost to use
maCadam construction owing to the
rapid wearing of the gravel road under
such circumstances and the conse-
Quently large expense for maintenance.
\ good gravel can always be told
when inspected, as it stands in place
In the pit Whenever it is hard and
compact in the bank and requires the
use of the pick to loosen 1t, 1t will form
a hard AMI compact road. Gravel
which contains a small amount of fer
ruginouS clay and has angular, rough
fragments of stone Is the best that can
be obtained. Gravel mixed with sand
or composed of smooth, rounded frag
mentS of stone does not compact and
form hard, smooth road surface and
is Of littl" use except for general fill
ing. To get the best results from gravel
which IS formed of various sized frag-
ments it should be screened, all pieces
two inches i'm size being thrown to one
side There are found in many places
gravel deposits which contain few
fragments over two inches. Such gray
cl does not need to be screened, but
could be spread upon the road directly
from the pit unless too sandy.
The two inch gravel is spread upon
the roadbed to such n depth that whEn
rolled 1t Will have a thickness of three
to four inches. over this first course
is spread the second course, composed
of the smaller gravel with fragments
one inch or less in size. The second