The Manchester journal. [volume] (Manchester, Vt.) 1861-current, 1913-01-09

ment In such cases the unstable ma
teriai should be removed and replaced
with gravel or sand. and wherever
practicable the earth subgrade should
be thoroughly rolled. preferably with
steam roller. and made to conform In
crown or Gambler to the surface Of the
| finished road Sandy subgrades may be
| improved by the use OF thin layer OF
4 clay or soil
There are two forms OF drainage es
sential in road building. a. surface
drainage and t2i subdrainage. There
are three essential points to be con
sidered IN connection with surface
drainage IL The surface Of the road
should he OF such shape that water
viii quickly drain from II 10 the side
bitches; GU the side bitches should be
adequate IN size to carry. without
overflow the ma ximum rainfall. and
they should be of such depth and
grade that water Will travel easily to
low points on the road, and 81 from
the low points there should be suitable
outlets to convey the water to the
natural drainage Of the country.
Water should never be permitted to
remain under q macadam road: con
sequently subdraInage must be resort.
ell 10 at times, Water softens the
foundation. allows the broken stone TO
lie forced into II by the traffic, and In
freezing 1t expands and dislodges the
broken stone. destroying the bond
There are several ways Of removing
the subsurface water, 1D by raising
the subgrade: ca by side drains con
sstlng Of narrow trenches filled with
broken stone. with pipe five or six
inches In diameter near the bottom A
drain Of this type should have fire.
OF cuIvert Is carried under the road at
suitable points.
Another type OF subdrain that IL
much used In Massachusetts Is the "Vr
drain 1t consists In shaping the sub
drain in the form Of ~" the angle
being at the center Of the road This
IL filled with coarse stone up to the
foundation grade and has frequent side
outlets. This type is rather expensive
and very frequently can be dispensed
with by raising the subgrade with
suitable sand. gravel or clay.
Another type OF drain practical for
side bill locations is a subside drain.
located on the upper side Of the road
TO Intercept aud provide an outlet for
surface aud ground water before II
reaches the road proper
Great care should be used In properly
grading road
The practice In America IL generally
to plare the maximum grade at per
rrDr TOR Important roads. as horse
;an lrpi without difficulty up such a
'ra,ie. and another important consider.
stion IN connection with grades Is that
4 tnnca lam surface can only b. main
tanned al great cost on steep grades.
10 fixing the grades the engineer |
should 50 adjust the cuts and dis MS TO |
Dsks the least possible wsste OF mate |
rial. and III this he must not overlook /
the FACT that some materials shrink TO /
; great eriepi when taken from the
.uts and placed 10 the fills This Va
les with the material. bnt averages
about Is per cent. The careful enH
neer Will ret his grade stakes not
more than Hfty feet apart. and In M
case should they be over hundred. and
these will serve later for the macadan
work In grading ample materia
should be left TO form the shoulders
Care should he used In properly sIop
ing cuts and tlls to avoid as far as pos
sibie settlement Of material. A slope oil
not less Than one and one half 10 one
should he used Care should also is
taken TO have the gutter grades 80 nreo
thai there will be ri least a fall Of Ma
inches 10 each hundred feet In order e
provide surface drainage.
10 general any stone that IL to b.
used 10 road building should he test
81 for hardness. toughness. resista nee
10 arar and binding or ceEnenting val
ue. The specific gravity. weight pei
cGlie foot aud water absorbed sre also
drsermiped With such data a. his IN
hand aud knowledge OF the yolnme
and character OF trefie 10 which ID,
rosd IL subjected The engineer CAP
make an inieiilgeni selection Of the
brsi arallable material While the dis
hases. dIorltes and basslis. Hli com,
monty known as lrsprock. 10 general
m~es the conditions where mscsdam
fssd. are usesss4ry. Ssa Il l. aawlss &c