ned out and culverts open.

All of the maintenance for 10 miles of earth road can be accomplished
by one man giving his entire time to the work, and that is the only
method that has proven adequate to the problem.

EARTH ROADS IN ARID REGIONS

In areas where the rainfall is less than 18 inches per year, and
especially where it is 10 inches or less, an entirely different road
problem exists. The effect of precipitation is of significance
primarily from the standpoint of erosion, and the design of cross
section and ditches and the culvert provisions are entirely different
from those necessary in humid regions.

Frequently the rainfall in semi-arid regions will be seasonal and
provision must be made to care for a large volume of water during the
rainy season, but, in general, road design is adapted to prevention of
erosion rather than to elimination of ground water effects, or the
softening effects of surface water. Generally the rainy period does
not last long enough to warrant expensive construction to eliminate
its general effects. In fact, the saturation of the soil is more
likely to be a benefit than otherwise.

Earth roads are likely to be satisfactory except where the traffic is
sufficient to grind the surface into dust to such an extent that an
excessive dust layer is produced. In such locations the problem is one
of providing a durable surface unaffected by long continued dry
weather.

Grade reduction will have the same importance as in humid areas and
will be carried out in the same way.

Maintenance will consist in repairing the damage from occasional
floods and in removing or preventing accumulations of drifting sand
or dust. Crude petroleum oils have been satisfactory for maintenance
in such locations when used on stable soils.

=Value of Earth Roads.=--The serviceability of the earth road depends
to a large extent upon the care exercised in its maintenance. The only
part of earth road construction that is permanent is the grade
reduction. The cross section that is so carefully shaped at
considerable cost may flatten out in one or two years, especially if
the road goes through unusually wet periods. Traffic will continually
seek a new track during the period when the road is muddy and is as
likely to cross the ditch to the sod near the fence as to use any
other part of the road. Continual and persistent maintenance is
therefore essential to even reasonable serviceability. At best the
earth road wi