The daily Missourian. [volume] (Columbia, Mo.) 1916-1917, 1916-08-09
COST Of A MACADAM
ROAD IS TOO GREAT
Uncle Sam Says it Won't Pay
in the Small City or
Rural BywayS.
METHOD is CHANGED
Porus Roadbed, Light Grades
and Few Curves Is the
Advice Given.
BY United Press.


WASHINGTON, Aug. 9.-"The Maca-
dam Road" said the United States Of
flee of Public Roads today, sis par
ticularly adapted to main highways
connecting centers of population, but
! is not satisfactory for city streets and
is too expensive for rural roads other
than main highways or pixies" The
department has been investigating.
From twelve to fifteen feet is recon-
mended as a suitable width provided
the road is fianked on each side with
firm shoulders from three to five feet
wide, to prevent shearing of the sides
by wheels.
The Macadam method of road con-
struction was first introduced about
the beginning of the nineteenth CEN
tury in England by Scotchman named
John Louden MacAdam
The chief features of this construc-
ton, which has since become one of
the foremost methods of road-building
in every country of the world. are:
raised. thoroughly drained. and
crowned earth foundation sub-sur-
face of brOken-stOne fragments, not
larger than 1-2 inches in diameter
and of uniform size; surface binding
of stone dust and screenings.
Method Is Now Modified.
During the last forty years this
method has been modified and the
stone fragments are graduated in size
with the coarser stones at the bot
tom.
Recently various bituminous pre-
parations have been added to the sur
face of binders. Heavy. petroleum
oils, asphalts. bituminous cements and
tar mixtures are now used largely for
this purpose The addition of some
such binding material renders the road
imperviOus to the damaging action of
water and forms a hard, smooth resil-
lent surface
Although it formerly was thought
necessary to surafce the road with a
layer of macadam from eight to twelve
inches in depth, Uncle Sans road eX-
perts declared the surface should be
as thin as is consistant with durability
not over six inches deep in any case
and often only three. This saving of
surfacing material greatly lowers the
cost of the road, without detracting
from its wearing qualities in the least.
they contend.
ROadbed Should BE Porous.
The roadbed should be porous mater
ial. well-drained. and should be free
from clay or loam
Grades exceeding 6 feet to every 100
feet of road are considered excessive
for heavy traffic Curves with less than
200 foot radius should be avoided.
Build around the slope of hill-not
over it. Build as straight as possible,
always considering grade first A
special recommendation is made by the
Office of Public Roads that the surface
crossing of railroad tracks be elimi-
mated by culverts or overhead bridges.
Trap rock is considered by the Gev-
ernment experts as the best for road
building purposes. althoug some gran
ties and the harder limestones give |
good results. The United States Of |
flee of Public Roads tests samples of !
rock submitted to it without charge. |
and furnishes advice as to the fitness
of any kind of sample for roadbuilding.
The Cost Varies.
The cost is entirely dependent on |
local conditions and the availability of |
materials. However. an estimate of
the cost Of the macadam surface. foun- |
dation and drainage costs eliminated,
places the average expenditure. where