Evening star., 1924-10-27
Old Gravel Valuable
As Base for New Road

To tho Editor Of The Star:
An article in The Star of Septem-
ber IA. entitled Seek New surface
in Road Building-Research Councll
Wants Material to Effect Big Saving
ON Secondary Highways" has at
tracted nv interest. 1t is pointed
out that our gravel roads, whlch
cost in the neighborhood or ss'OoV
a mile to construct, and which are
capable of carrying light traflc OF
few hundred vehicles day. have
to he replaced by pavements costing
sS5 600 a mile, in order to carry
economically a greater traffic. IT is
nointed out that these $50, ,ooo-a-m mile
roads are capable of handling any
amount of traffic and that there Is
sorely needed a pavement Whch WIN
fall somewhere between the SS,eO0
gravel road and the $4,000 higher
tvpe of construction to handle tranc
Of from 500 TO 1000 vehicles per day
which is the traffic on by Tar tne
large majority of our highways In
order to fill this gap on roads car
rving a medium traffic l would sug-
cest the following procedure:
The $4,000 gravel highway which
has successfully carried light
traffic need by no means be dlscarded.
II should be retained and utilized as
a foundation for high-type sur
facing. Years of traffic have com
pacted the gravel until it is firmly
consolidated, but owing to It's lach
of binding material, it is unable TO
stand the abrasive force of a great
number of fast-moving automobiles
If the surface of the old gravel is
trued UP it is then ready to receive
q course of from 2h to 5 inches OF
broken stone After a light rolling
to set this in place the stone should
be bound together with an asphalt
paving cement, which should be ap-
piled at the rate of ia gallons per
square yard. The surface is then
covered with stone chips and thor
oughly compacted by rolling. In or
der to make the pavement absolutely
watertight it is often well to apply
second application of asphalt ce-
ment, this at the rate of about one
half gallon to the square yard, which
Is covered by small stone chips and
finished by rolling. This surface.
known as the asphalt macadam type.
can be laid at from 75 cents to 81
per square yard, which is approx
mately $4,000 a mile, the figure sug-
gested in your article of September
II, thus effecting a saving of ap-
proximately $4,000 per mile, or
making possible the laying of over
four miles instead of one mile.
The old worn gravel road, which
Is costing annually large sums to be
maintained, is too frequently dis
carded as worthless and an entire
new pavement laid. The practice de-
scribed above of saliva ging the foun-
dation for n new pavement is not
necessarily a new one, as 1t has
been tried successfully in n number
of instances and deserves being
brought to the attention OF the paw
ing officials and the general public.
The asphalt macadam type of pave
ment is capable of handling COM
paratively heavy traffic successfully
with a maintenance cost of consid-
erably less than the cost of main
tanning a gravel road under light
traffic of but a few hundred vehicles
Per day. Massachusetts State High
way Department, which has under it's
jurisdiction an area of 3,079,610
square yards of asphalt macadam
pavement, gives as the average cost
for maintaining them for the year
1928, 2.s5 cents per square yard, or
an average for an 1S-foot road of
1901 per mile.
r. E. PENNYBACKER,
General Manager the Asphalt Asso-
citation.