hes along a highway can be prevented by
constructing weirs across the ditch at frequent intervals, thus
effectually preventing an increase in the depth of the ditch.

Wherever water flows at a velocity sufficient to produce erosion or
where the drainage channel changes abruptly from a higher to a lower
level, paved gutters, tile or pipe channels should be employed to
prevent erosion.

=Private Entrances.=--Entrance to private property along the highway
is by means of driveways leading off the main road. These should
always be provided for in the design so as to insure easy and
convenient access to the property. The driveways will usually cross
the side ditch along the road and culverts will be required to carry
the water under the driveway. Driveways that cross a gutter by means
of a pavement in the gutter are usually unsatisfactory, and to cross
the gutter without providing a pavement is to insure stoppage of the
flow at the crossing. The culvert at a driveway entrance must be large
enough to take the ditch water readily or it will divert the water to
the roadway itself. Generally end walls on such culverts are not
required as in the case of culverts across a highway.

=Aesthetics.=--Much of the traffic on the public highways is for
pleasure and relaxation and anything that tends to increase the
attractiveness of the highways is to be encouraged. Usually the
roadside is a mass of bloom in the fall, goldenrod, asters and other
hardy annuals being especially beautiful. In some states wild roses
and other low bushes are planted to serve the two-fold purpose of
assisting to prevent erosion and to beautify the roadside. In humid
areas trees of any considerable size shade the road surface and are a
distinct disadvantage to roads surfaced with the less durable
materials such as sand-clay or gravel. It is doubtful if the same is
true of paved surfaces, but the trees should be far enough back from
the traveled way to afford a clear view ahead. Shrubs are not
objectionable from any view-point and are to be encouraged for their
beauty, so long as they do not obstruct the view at turns.

CHAPTER V

EARTH ROADS

Highways constructed without the addition of surfacing material to the
natural soil of the right-of-way are usually called earth roads. But
if the natural soil exhibits peculiar characteristics or is of a
distinct type, the road may be referred to by some distinctive name
indicating that fact. Hence, roads a