The suburban citizen., 1902-09-20

IA
~ tion is to roll down the centre
NJ first, which has tendency
to fatten out the road and
testroy the proper cross slope grade.
When the finished road has been tested
w the engineer and found deficient
along the centre line, only one OF two
ourses is open to the engineer to bring
>le road up to the established grade
ether to disturb the entire surface or
% put on an additional quantity Of
screenings. 1t is seldom that the first
course is resorted to, but too frequetly
The latter. a road brought up in this
way with screenings will always be an
object Of great solicitude and an eX.
penslve road to keep in good repair
The practice of centre rolling has a
tendency also to leave the outer edges
and three or four feet of the macadam
very loose in their construction, while
he centre. when the road is first turned
over for travel, is the best part OF the
road for use, which by use in short
time breaks its bond and works out
oWard the sides. and then trouble com.
nences. In building macadam or any
other pavement there are no little
:hings, from the plowing up Of the road
10 the last rolling the road receives.
Very much depends even upon the
Jumping of the load Of metal in the
'oadbed. Under no consideration what.
aver should a load of stone be allowed
% be dumped on the roadbed proper,
lnless every part of the load, before
'ollng, is removed and placed with
Jhoyels in the place it is to occupy,
FOR the simple reason that, when dump.
ing is resorted to, whether from a cart
or from a reach wagon, uniform roller
pressure cannot be had upon all parts.
The part which is brought to the cs.
.ablished grade by shovels will respond
20 the rolling, but where the body Of
The stone fell there will be resistance,
which in time will develop a weakness
N the road. Every part of the road
.hould receive equally the same amount
Of roller pressure.
He has used telford only in special
cases where the foundation was uncer.
ain. A thirteen-inch telford road will
not wear as well as a seven-inch ma
,adam road upon a gravel or mixed
earth or sand foundation. The rigidlty
If the thirteen-inch pavement con.
1uces to the destruction of the road,
while the elasticity Of the foundation
IF a seven-inch macadam tends to its
! preservation; so he has not extended
he system of telford roads any further
han was absolutely necessary. pre-.
eerring to use good sub-grade material,
with plenty Of rolling, and to extend
his system of macadam at less price
than If the roads had been of telford
construction.
If a macadam road is properly built
here is no necessity for the application
Of screenings in maintaining the road
Screenings placed upon an old ma.
2adam road must lie upon the surface
where in dry weather it is dust and in
| wet weather it Is mud. The time to re-
pair a macadam road is when the
stones begin to show bare, when the
! screenings or wearing surface of the
:oad has been lost. Then, instead of
screenings, stone ranging in size from
one-half inch to three fourths inch
longest diameter, should be used. II
he three-fourths inch stones are spread
| upon the surface of the road, over the
full width Of the travelled part and to
the depth Of about three-fOurths of an
inch mo greater depth should be ap.
! plied), they will not need water or
/ .olling. The point of contact will be so
near the point Of resistance that the
full crushing force Of the hoof or the
weight Of the load upon the wheel will
| fracture the stone The fracture will
Weld just a small amount Of dust. or
1etritus, which falls quickly to the
lnder surface and is protected from the
/ heat Of the sun, so that it will not dry
/ out and from the wind, so that 1t
cannot blow off. In a very short time,
the ordinary travel will reduce all this,
Of course, and a gradual healing pro.
| cess will go on over the entire surface.
He has tried this method in Connect.
cut, and has not found a single failure.
1t yields a very large return for the
money invested. If a road has broken
up-which condition, however, should
not be allowed to Occur-there is only
one thing to do, and that is to apply
whatever stone is necessary, and, OF
course go through the process of
screening, wetting and rolling. g.-Ab.
stract of a paper by ]. H. Macdonald,
Highway Commissioner of Connect.
cut.