Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1912-09-14

ABOUT Ia per cent 1ne caFe1nt enG1-
neer will set his grade stakes not
more than fifty feet apart. and in no
case should they be over hundred. and
these, viii serve later for the macadam
work In ending ample material
should be left 10 form the shoulders
Care should be used in properly Stop
ing cuts and ills to avoid as FAR ~ pos
Sible settlement of material. 4 slope Of
not less lhan one and tjIIe half TO one
should be used. Care should ALSO tie
takeE 10 have the gutter grades 50 liked
that there will he ut least fall Of six
inches IA each hundred feet in order to
provide surface drainage.
In general. any stone that is TO be
Used in road building should Dp test
I'd for hardness, toughDeSS. Resistance
10 wear and binding Or ceuieirting val
ne. The specific gravity. weight per
rubic foot and water absorbed are also
determined. With such data as this in
hand and :: knowledge OF the volume
and character Of traffic to which the
road is subjected the engineer can
make an intelligent selection Of the
best available material. While the dia-
bases. diorites and basalts, all com
monty known as traprOck, In general
meet the conditions where macad8m
roads are necessary. yet il is unwise to
select a rock by SPECIES alone, as they
all vary greatly.
:. There are two distinct types of bro
ken stone road in use today. known us
macadam aud telford roads. The mac
adam road Of today is 10 different from
the typespecified by Macadam that the
relation is hardly recognizable. by the
best practices used this road consists, in
4 foundation course of two and one
half inch stone Of varying thickness.
This foundation should be thoroughly
rolled with u steam roller and not nfIre
lhan Il thickness of tive or six inches
rolled ut time. 0n top of this Is
placed Il three or four inch layer of one
and OiIe-half inch stone. and after thor
ough.v rolling Il layer Of rock screen
ingS below, lireer, quarters Of an Inch in
size Is spread. This layer Of screenings
shonid he Sufficient only to fill the sur
face yoids of5the MeaRiiE <cofi%p and
should not I've appsiatl all in 'otbe layer.
Zach afl'icsttion of SCREENINGS shoa.d
he Hoiled in before the uextaf Sfiratiunl
Is made After the surface has been
thoroughly tiiled with screenings t.,p5
road sIiould be we'll spriuklpd with ia
wafprfng cart and rolled with IL steam
roller Ertil it il thoroughly beaded.
This roisin. should coItinUe until the
surface ceases 10 wave Ia front of the
roller. g.. - +. . ..-., .>...... se-..-5,<
ia Stone should never he dumped ON the
road. aiisi,iit specially devised spread
ing wagons are not used the stone
should he dumped OH boards ard spread
from Them on 70 the road. The con
tractor should be required to place
about a hundred tons IF No. stone
and screenings at a convenient place
for each mite of road built for the pur
pose OF making future repairs. +.,..s.. y
The telford road Of today varies only
from the ain;rcati:ifa road in TINT 1t has
n hani paved fo,tndation course. con
sisfiBg ~ course sStoae eight or nine
inches in its greatest dimensions
These stones are placed on edge in tine,
.s;iijgfsslle. bS ftTd OH their lroadest
:baSes and at right angles to the line of
the road. and all irregular portions are
lroken or with htI,nmprs. -. -
p This tyre of road was. first designed
by h French engineer named Ttesaguet
forty years in advance of Te.fofd. The
roads bHilt by TelTord hssl fat sab
grades. but those constructed by Tire
Saguet had cambered suhgrades. which
ure supposed to have the effect of a
keystone arch.aa and this is the form in
which they are constructed today. 1t
IL rather, an Interesting fact that in
France practically al of the broken
stone roads aEe OF the Macadam tyre,
while in England they are largely of
the Tresaguet or Telford type.
Experience has proved thdt the only
way. I'm which roads can be kept in
COOL condition and at reasonable cost
is 10y, continuous and intelligent main
tenance. 1t is a mistaken although un-l
fortunately general impression that
certain, types Of road are permanent.
No permanent road has ever been con-
,struetad Or ever can be-
Cutters. catch basins and culvertS
ought by all means to be kept clean.
and small guIIies in shoulders should
be filed before. they become too large.
The loose stone which nearly always
appears on, the surface Of macadam
road the first spring after it is built
should be raked up and stacked for fu-
ture use. Small holes and fheipient