Los Angeles herald., 1910-01-23

roadway too soft to sustain heavy traf-
| fic, particularly during the warm
weather. Further, the use of oil is
extremely uneconomical because a
! large amount of waste occurs through
the evaporation of the volatile portions
of the oil which are too unstable to re-
sist the ordinary atmospheric tempera-
| ture.
In Southern California particularly a
| bonded mGeadam made with heavy
residuum will be the most satisfactory
and durable.
We have in the summer season a
| long period of -a5arm weather with very
| few cool days, causing the oil bonded
macadam to soften.
Unless it is made with a heavy re-
siduum containing large proportion of
fixed bitumen it will become soft. The
objection made to the effect that the
| first cost of using such a residuum is
greater than oil has very little force in
view of the fact that subsequent MAIN
tenance of roads bonded with a heavy
substance is very much less than roads
bonded with oils. The oiled roads be-
come so uneven that they have to be
continually resurfaced in order to keep
them in a passable condition. This
expense will in a few years more than
make up the difference in first cost, and
bonded macadams made with heavy
residuums are not more economical
than those made with oil, although
their first cost is slightly greater.
In the eastern states and in Europe,
where asphaltic residuums are expen-
sive and difficult to obtain, various
preparations made from coal and coal
tar are used for bonding macadams.
These, however, are made so heavy as
fp no otiA1lIxr 40 1e, o11,, h
ier residuums, showing that experience
elsewhere leads to the same conclusions
as here.
Lateral Protection to Roadways
The present method of protecting the
edges of the macadam road being con-
structed in Los Angeles county is to
make an oiled shoulder on the road sew
en- feet wide on either side of the six
teen-foot strip of macadamized road.
While this will be temporary protec-
| tion to the margins of the macadam, it
is unquestionably true that future trou-
BILE will result on account of the break
ing down of the oiled surface along the
edges of the macadam.
The passage of heavy vehicles near
the oiled shoulder will soon break the
contact and permit the formation of a
groove into which water will filter and
pass below the macadam. Injury will
therefore result to the foundation wher-
ever the soil is such that the presence
of water softens it.
There are two remedies which can be
applied to prevent this from occurring.
! One of these is to slope up to the sur
| face in a distance of four or five feet
where it would gradually taper out into
| the oiled shoulder. In this way there
would be no marked contact between
the oiled road and the macadam to
cause the formation of a groove or gut
ter between the two.
| A still better method, however, would
be to extend the rock out on a level
until it would pinch out at its inter-
section with the curve of the road sec
tion. This method would involve con-
siderable more expense than the former
and might require the modification OF
the curves by sharpening them slightly
! beyond the sixteen-foot strip.
| In discussing this. matter with A. e.
Loder, chief engineer of the Los Ange-
| les highway commission, it developed
that the law under which the work is
being done limits the width of mac
adam to sixteen feet. IL would SEEM
however, that this objection is answered
by the fact that the rock outside of the
! sixteen-foot strip will not be a mac
! adamized road in the sense intended by
law, but a protection to the roadway
just as the oiled shoulders now CON
strueted are added for the porpose ol
such protection.
1t would seem that this question Il
| so important that the legal advisers
of the highway commission should pass
upon it, and if the law permits it tC