Honolulu star-bulletin. [volume] (Honolulu [Oahu, Hawaii]) 1912-2010, 1917-09-17

| the greatest economic Importance in
road building and cannot be too great
! ~ emphasized There are numerous
examples of roads and streets on this
island today which plainly show the
effect of insufficient preliminary work.
Had more time been spent in a thor
ough study of conditions before work
was commenced, the public would I'M
doubtedly have saved many thousands
of dollars.
Matter Of Location
One of the first things to be con
! sidered under the head of preliminary
investigation is the matter of location.
This includes, principally, a thorough
study CT grade and alignment. II is TO
be remembered that the only features
Of road or street which may be con
| sidered truly permanent are those OF
| line and grade. The first cost Of do
| ing this work properly is the only one
which needs to be considered.
THE matter of curves must be given
careful thought in view of the rapid
development in the speed and volume
lCf automobile traffic. S1arp curves
are the places where collisions are
| liable to occur due to an Obstructed
view. In highway work, a minimum
radius should be established for ali
curves. For instance, any attempt to
maintain a minimum radius as low as
100 feet along the Pail Road in Koo.
laupoko would be ridiculous. 1t is the
present intention of the city engineer
ing department to maintain minimum,
radius of 200 feet forsall curves on the
proposed reconstruction of the Oahu
belt road.
In city work sharp curves at street
intersections are unavoidable. If the
streets are wide, short radii may be
used at curb intersections. On mar
row streets, however, the greatest
length of radius possible should be
used in order to facilitate traffic in
turning from one street into another.
The grade established for any high
way or street Improvement depends
upon several factors. In street work
| the requirements of abutting property
| should be given every consideration
consistent with good design. Before
! fixing a grade our present practise is
to take elevations along the center of
the roadway, both curb and property
| lines and all other controlling points
such as street car rails, bridges and
CulVerts. The grades of all intersect-
| ing streets are also ascertained. A
final grade is fixed which best fits all
the conditions involved. In highway
work, similar regard is had for all
controlling features in determining the
final grade.
Foundation and Damage
I'm addition TO the location feature,
there is the equally important matter
of foundation and drainage. BY far
the big majority OF our present pave
ment failures are due to a lack of
proper provision for these essentials
| The earth, or subgrade as it is called.
bears all the load of traffic; the pave
ment is merely a crust to protect the
earth from the direct action Of traffic
and the softening effect Of water,
When the subgrade for any reason
ceases to support the traffic load, the
pavement must act as bridge.
"A solid foundation implies a dry
foundation. Care should be taken that
| the design of road or street makes
ample provision for this requirement
If anyone has the impression that
| the requirements for proper founda
ton and drainage can be disregarLed
where concrete is used as road ma
terial or pavement base, he should give
up the idea at once. Concrete is by
no means a cure-all for road troubles.
| Even greater care should be exercised
in the use of this material than has
| been the practise in the past
H.
| sidered also. The maximum yearly
range in temperature, for instance, is
the principal factor in the selection OF
the class of bituminous material TO be
used on the work
Character Of Traffic
"A feature of tremendous import
aLce which is often overlooked in
| making a preliminary investigation is
that Of traffic The character Of traf.
, &c, whether horse-drawn or automo,
bile, is as much factor in the de-
sigu of the pavement surface as 1t is
in the selection Of any particular type
The total weight Of traffic acting upon
the pavement in given unit of time
! is another controlling feature.
"Horse-drawn traffic is destructive
. to a pa"ement ON account Of the con
! tinual pounding action of hoofs and
the tracking Of iron tires. Bituminous
surfaces on concrete CT water bound
macadan roads are difficult to main.
tain under large amount Of horse.
drawn traffic for this reason.
] Automobi!es Earntu!
"AutcmoEiles a-c destructive on &c
count Of the sho2riIg ac:!cn Of the
tires. Water houn& macadar read
ravel CIT and disappear a. due, unGe
this class OF higb-GPeed traffic. Aut,
mobiles der:and Tes!!tency n ,ho sj:-,
face Of the pavement. Their cnormOu,
development calls for :. new ara moro
permanent type OF construct y.
Motor trucks. however, pI1ent the