Pullman herald. [volume] (Pullman, W.T. [Wash.]) 1888-1989, 1909-05-14
HIGHWAY EVOLUTION

as well as need for improved high
ways is greater than ever before. But
the old type of water bonded maca-
dam is no longer equal to meet the
demands made by modern highway
traffic, except in certain isolated To-
callties. Slowly, however, reluctant
ly' we are being forced to recognize
the fact that our city streets and
those highways which serve as con-
meeting links between different cities
or points of interest to the tourist
the water bonded macadam is a
Ial'uIe. once, under other condi-
lions than those we have to meet TO-
day, it was a splendid surfacing:
now 1T is but a useless waste of
money.
The demand of modern traffic is for
a resilient binder which will not
crumble to dust during our dry sea-
son and SO be blown away by each
rapidly passing vehicle nor allow
displacement of the stones in the
road surface when called up to trans
nit the heavy shear of a rapidly NOV
ing automobile.
Such binder is found in the heavy
asphaltic oils of Southern California.
A properly conducted macadam road
with the top surface bonded to the
depth of two or three inches with a
good oil is practically dustless and
Will not rayel or go to pieces during
the dry season even under heavy
automobile traffic. The amount of
oil required to properly bond the
road surface to a sufficient depth var
les from one and one-eighth to one
and one-half gallons per square yard
of finished road surface. If the oil
is purchased in carload lots the ad-
dltional cost is small. Here in the
Palouse region the cost of the oil
will be about 5 2-3 to cents per
canon, or the additional cost of the
oil bonded macadam due to the cost
of the oil would be from 6 to cents
per square yard Of completed road
surface. This is a ridiculously low
quantity when one considers the adj
ditiOnal life given to the road 20 say
nothing of the comfort and pleasure
derived from dustless road by both
travellers and way side dwellers. In
many places the dust nuisance has
become almost intolerable and the
extra cost of theoil would be gladly
borne in return for a dustless road.
There is also the reduced cost of
maintenance, which is no small item
under the conditions which modern
traffic impose on our roads. Some
of our New England and eastern
states are finding three hundred dol
lars per mile annually insufficient to
properly maintain water bonded ma
cadam on main roads. In England
and all the continent of Europe the
cost is even greater.
While we have not as yet reached
the stage where the traffic on our
roads compares with that on the
highways of New England, those cen
ditions are rapidly approaching. 1t
behOoves us to build with our eyes
open and profit from the lessons
now so dearly being paid for by the
east.
Oil bonded macadam also makes
very good pavement for city or
town resident streets. 1t is of low
first cost, durable, free from dust,
and almost noiseless, thus possessing
all the essential requirements in res
idence districts.
California has done most of the
pioneer work in developing oil bond
ed macadam roads and streets. Mr..
IL. NJ. Morton, highway engineer of
San Joaquin county, which county
by the way, has just lately voted to
eXpend 81 100000 on a comprehen-
siye system of county roads, has this
to say of oil bonded macadam: "An
oil bonded macadam will make very
suitable streets for resident sections.
Gravel for the base is used quite ex-
tensiyely here in Stockton for the
same purpose. The top is bonded
with about l is gallons of oil per
square yard; one and one-half gal
Ions is about the maximum of oil
used per square yard needed.
Limestone screenings seem to
give a better surface than trap
screenings. There is something about
the limestone which has a peculiar
affinity for oil, and it seems to make
a harder, tougher mat or course than
trap screenings. l saw this at Riv-
erside where they build fine, hard
dustless roads from a limestone so
soft that you can scratch it with the
finger nail.
There are a few essentials to be
always kept in mind when using oil
for road building. Try to get an oil
II, Of