The Providence news. (Providence [R.I.]) 1891-1906, 1895-05-20
R. |. HIGHWAYS.
Further Extracts From Com
mittee's Report.
The Matter OF Road Surface Con-
struction.
Different Kinds of Materials and
Methods Considered.

An earth road, commonly built is but a
poor substitute for a stone or graveled sur
face. Yet. with earth alone. very passable
road can DO made and maintained If sufficient
care is taken to have it thoroughly drained,
and the surface Of proper shape But, to
obtain road which shall be hard and smooth
at all seasons and under all conditions Of the
weather, a stone surface must be made, either
by the use of broken stone or gravel alone
or by laying a foundation of large stones with
top or wearing surface of gravel or broken
stone.
road surface, built OF broken stones alone,
was first introduced into England by Mac
adam. and road so built is called, from his
name, macadamized road.
Telford had previously built roads having
broken stone surface, and foundation of
large stones. but Macadam maintained that
the large stones We're useless and injurious,
and preferred to lay the broken stones upon
the natural soil. claiming that the large stone
foundation acted as an anvil upon which the
surface material was gradually ground up by
the traffic With the introduction OF the steam
road roller and tho stone crushor, much i'm
provement has been made in modern mac
adam roads. The method of constructing a
macadamized road surface is TO spread evenly
upon the road-bed, prepared as previously
described, layer of from 4 TO inches of
broken stone, the largest Of which shall not
exceed 215 inches in any dimension, and roll
with steam roller of suitable weight. A
second layer of stones, not larger than two
inches in any dimension. is spread to a depth
OF four inches ON the surface so rolled, and
this rolling continued. Finally. coating of
about one inch Of the screenings which pass
the one inch screen of the crusher is applied,
well watered and rolled until the surface boz
comes hard and smooth. From eight to IL
inches Is the usual depth of a macadam road.
The objects to be attained by a macada-
mized surface are hardness and smoothness,
imperviousness TO water from above and to
mud from below. The only difference be- |
tween the modern Teford and macadam |
road Is In the foundation which, in the Tel |
ford road, is composed of large stones set by |
hand upon edge, lengthwise across the road |
These stones should be carefully set and the |
spaces thoroughly filed with spauls, and the |
spauls driven until the stones are firmly and |
wedged together. All projections
above the general surface OF these stones
should be broken off by the hammer until the
surface is even, and pains should be taken to
MI the interstices as completely rs possible TO
prevent the mud from working up from be-
low. Upon the foundation thus formed, Mac
adam, or gravel, is spread and rolled, as above
described.
In many cases 10 is not necessary TO exca-
vate to depth Of from eight to u inches, for
the pupose OF putting on layer of stones of
The same depth, the old road-bed itself being
, sufficiently good foundation and only re-
auiring the addition of good stone surface
rom two TO four inches thick, thoroughly
rolled. TO make an excellent road for all
seasons. Indeed. an old gravel road Is deemed
,y leading road engineers to make the best
possible foundation for road surface.
Gravel, II properly prepared and laid,
makes an excellent road surface, and is con-
idered by many TO make more agreeable
urface to ride over than broken stone. Most
u the gravel found in this State is round and
mooth and requires to be mixed with proper
,inding materials, such as clay or loaming
oii. II any success Is expected from its use
IS road material Pit gravel should, usus
lily, be screened, as il contains too much bind.
ng material. Gravel should be spread upon
he road and rolled in layers in the same
manner as broken stone. Gravel can be ap-
'lied to Telford foundation to form wear
ng surface in place Of broken stone, If de-
ired. The expense of screening gravel will |
'e moro than repaid by the superior condi-
ion Of the road formed by the cleaned ma
erials. and the diminution of labor in keep
ng IL in order.
1t ID very essential. in both broken stone and
ravel roads, that great care be taken TO use
tones OF the uniform size specified, and
hat all large or fat stones be removed A
nacadam road should never wear rough If
trict attention Is paid to this matter for it is
he unusually large stones which always cause
he roughness, providing. of course the road :
as been properly built otherwise. A surface }
& stones of uniform size will wear evenly. :
All road surfaces should have a transverse
rade or fall from tie center each way TO
he cutters. This fall should not be less than
ne-half inch to the foot and should in. .
rease as the longitudinal grade becomes .
teep, to prevent the formation Of gullies by .
nrning the water quickly from the road
arfaoe.
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