Evening star., 1923-10-28
down to a minimum by using the
two-inch thickness.
Uses Local Materials

SbcS hOC0I MAteElahs
Sixth. because asphalt enables the
be unsuita BILE for other form of con-
struction. For example, a hard stone.
which has no cementing value and is.
therefore. unified for waterbound
because the asphalt provides the
binding power which the stone lacks.
In another case a fairly soft stone
which would not be hard enough for
portland cement concrete may be used
with asphalt, for even If the stone
breaks down 1t forms with the as
pha.t tough mastic similar in some
respects to rubber mat.
Seventh. because the asphalt wear
ing course is easily repaired If any
part of it should become defective
and. when properly prepared. the
pavement is absolutely restored. the
new asphalt blending with the old
mixture. This Is only possible with
the flexible type of pavement.
Some engineers figure a pavement
as having two dimensions, width and
thickness, but the most important
dimension of all is length. The peo-
pie today need an enormous mileage
OF highways SO that they may get
tination. If a few miles of very
costly type of pavement are laid and
a gap Of bad road is left between the
terminus of the pavement and the
ultimate destination II Is much the
same as building a bridge half way
across the river and waiting a few
years to build the other half. 1t Is
not only common sense but civic
duty to utilize fully every existing
asset in the way of old pavements
in order to get mileage.
Second Problem.
The second problem. that Of provid-
ing new pavements, Involves the con-
sideration' of very, wide range of
highway method and design. A few
years back the so-called city types
of pavement were regarded as beyond
the reach Of the country road builder
because of their great cost. That was
In the days when a $4,000 to $4,000
per mile outlay was regarded as
quite liberal. Today the country
highway which costs less than $20,-
600 per mile is either regarded as a
shining example of extreme economy
or it is relegated to the ranks OF the
cheaper types" Now when We go into
cost levels such as these we are
scarcely abreast of the city paving
types and 1t is entirely practicable
for the farmer to drive from the mar
ket to town on 5th avenue or Broad
street type of pavement and pay no
more for it than he is now paying
for other types Of country roads. AS
matter of fact. the famous Lacka-
wanna trail is mostly composed. of
sheet asphalt on a portland cement
concrete base and compares favor
ably with the best pavements in the
best cities. Few state highway en-
gineers have had any experience with
city paving. as curiously enough
there have been very few city en-
gineers who have been placed at the
head of state highway departments.
II is inevitable that those pavements
which are able to withstand the
grueling wear and tear of city traffic
are capable Of withstanding any traf-
fic to which a country highway will
be subjected. The reason the city
asphalt type of pavement can be con-
structed for little if any greater
cost than bare concrete is because
the use of the asphalt top eliminates
the necessity for a rich concrete base
In other words, where the asphalt top
is not applied the portland cement is
used in the proportion of one part
of cement to four and one-half parts
~ ~'--'". while in the cases
where an asphalt top Is used the
~ semen, in the base is one
part Of cement to nine parts of sand
and stone. Further. while in the case
of the portland cement pavement q
metal reinforcement is usually re-
quired. this is not needed in a con-
crete base surface with an asphalt
top. These notifications. bring the
two designs fairly close in compara-