ter is allowed to
stand on a road the holes and ruts rapidly increase in number and size;
wagon after wagon sinks deeper and deeper, until the road finally
becomes utterly bad, and sometimes impassable, as frequently found in
many parts of the country during the winter season.

Road drainage is just as essential to a good road as farm drainage is to
a good farm. In fact, the two go hand in hand, and the better the one
the better the other, and vice versa. There are thousands of miles of
public roads in the United States which are practically impassable
during some portion of the year on account of bad drainage, while for
the same reason thousands of acres of the richest meadow and swamp lands
lie idle from year in to year out.

The wearing surface of a road must be in effect a roof; that is, the
section in the middle should be the highest part and the traveled
roadway should be made as impervious to water as possible, so that it
will flow freely and quickly into the gutters or ditches alongside. The
best shape for the cross section of a road has been found to be either a
flat ellipse or one made up of two plane surfaces sloping uniformly from
the middle to the sides and joined in the center by a small, circular
curve. Either of these sections may be used, provided it is not too flat
in the middle for good drainage or too steep at the gutters for safety.
The steepness of the slope from the center to the sides should depend
upon the nature of the surface, being greater or less according to its
roughness or smoothness. This slope ought to be greatest on earth roads,
perhaps as much in some cases as one foot in twenty feet after the
surface has been thoroughly rolled or compacted by traffic. This varies
from about one in twenty to one in thirty on a macadam road, to one in
forty or one in sixty on the various classes of pavements, and for
asphalt sometimes as low as one in eighty.

Where the road is constructed on a grade or hill the slope from the
center to the sides should be slightly steeper than that on the level
road. The best cross section for roads on grades is the one made up from
two plane surfaces sloping uniformly from the center to the sides. This
is done so as to avoid the danger of overturning near the side ditches,
which would necessarily be increased if the elliptical form were used.
The slope from the center to the sides must be steep enough to lead the
water into the side ditches instead of allowing it t