EARTH, SAND-CLAY, AND GRAVEL ROADS. 
6. Avoid turning: water from one intersecting road down the side 
ditches of another, 
side ditches. 
Also avoid draining adjacent fields into the 
CROWN. 
The proper crown to give the cross section of a road surface de- 
pends on two opposed factors : 
(a) It is desirable to get water away from the surface as quickly 
as practicable, so as to prevent the surface material from being 
softened by saturation or washed away by water collecting in, and 
flowing along, ruts. 
(h) It is desirable to keep the cross section of the road as flat as 
is consistent with good drainage, because traffic distributes itself 
over a flat road sur- 
face much better 
than over one that is 
heavily crowned, and 
an even distribution 
of traffic makes to- 
ward uniform wear, 
and comparatively 
light maintenance. 
There is also less 
danger of skidding 
on a road of flat 
cross section than 
where the surface is 
crowned. 
In general, the 
amount of crown 
should be greater on grades than on level stretches of road, because 
the tendency for water to wash away the surface by collecting in 
and flowing along ruts depends largely upon the steepness of the 
grade. Also the care with which a road is to be maintained may 
have an important influence on the amount of crown that should be 
given to the surface. It is evident that a road surface maintained 
in a smooth uniform condition will shed water off to the side ditches 
with much less crown than would be required where ruts are allowed 
to form. 
Instead of crowning the road surface sufficiently to prevent water 
from flowing along the traveled way and causing washes on steep 
grades, resort is sometimes had to "water breaks," or "thank- 
you-ma'ams," constructed across the road at short intervals. These 
water breaks may consist of either broad, shallow ditches or flat 
ridges constructed at a slight angle with the road so as to turn 
OPRREI2252 
Fig. 7. — Use of wooden breakers to prevent scour of side 
ditch. 
