The maintenance of an earth road surface in good condition consists in keeping it crowned and smoothed, so that water which falls upon the surface flows away immediately into the gutters without remaining upon the road long enough to do serious harm in softening it. If ruts and depressions are allowed to form in the road surface, they will hold water until it is absorbed into the road or evaporated, thus softening the road so that wheels will cut deeply into it, and gradually destroy its firmness.
The improvement of an earth road surface which is not in good condition must, therefore, be effected mainly by reshaping it into a form with proper crown to shedthe water. Its subsequent maintenance requires that it be frequently smoothed to prevent the forma tion of ruts. It is practically impossible to maintain an ordinary earth road in good condition by the method of annual repairs. Where this method is followed, the road is usually shaped up with a road grader, after it dries sufficiently in the spring, and may present a good surface during the summer and fall. It will, however, be worn hollow by the time bad weather sets in, and will be in condition to hold water and become saturated by heavy rains or melting snow.
Shaping Section. The form of cross section which should be used has already been discussed in Art. 25, and the drainage of the road should be provided for where necessary as described in Chapter II. For cleaning the side ditches and forming the surface of the road, the ordinary road grader, or scraping grader, is used as mentioned in Art. 26. In this work, the blade of the grader is set so as to carry the material from the ditches toward the middle of the road, and repeated trips are made until the proper crown is given to the road surface. In doing this, care should be taken not to leave a ridge of soft material at the middle of the road, but to spread it evenly so that travel may take any part of the road surface, and thus compact it evenly. This may be accomplished by slightly raising the end of the blade of the grader nearest the middle of the road. In using the grader, the amount of material moved and its distribution are controlled by changing the angle at which the blade is set, and the elevation of its ends. Experience in handling the machine is necessary to its skillful use, and the amount of work required in forming a road is largely dependent upon the skill and experience of the man operating the machine.. Good results in such work also require
that the teams used be well broken to the work.
Where roads are shaped in this manner in the spring, the work should be done before the surface has become dry and hard, and while the earth is in condition to pack and unite with the surface upon which it is placed. After the ground has become dry and hard, the work is more difficult and expensive, and the road is usually left in bad condition because the material moved, being hard and lumpy, does not pack readily under travel.
Smoothing Surface. The maintenance of an earth road in good condition requires that surface be fre quently smoothed so as to prevent the formation of ruts, which may hold water when rain comes. Repair ing the road by reforming the surface when it has gotten out of shape may improve it so that it will remain in fair condition so long as weather conditions are favorable, but when rain comes the surface will be softened so that wheels cut in to a small depth, making small indentations. These, if allowed to remain, will hold water at the next rain, causing the road to become soft to a greater depth and deeper ruts to form. If, however, after each rain the road be smoothed out, eliminating the ruts, and moving a little earth toward the middle of the road to replace that lost through wear, the road surface will be hardened and improved at each treatment, and will not retain water when con tinued rains come upon it.
The smoothing of the road surface should be done when the road is drying out after a rain; when it is not too muddy, but before it has become hard. The earth is then in condition to pack readily under travel, and will form a smooth hard surface when it becomes dry. If undertaken when the surface is too wet, it may be muddy and sticky to work; after it becomes dry, no good can be accomplished by working it, as it will not pack smooth and hard. When a road is kept shaped up by smoothing it after each rain, the earth composing the road surface becomes puddled, through being worked while wet, until it becomes practically impervious to water and forms a very hard crust on the surface. This effect is observed upon all soils which soften upon absorbing water, and become hard when dry, but is most noticeable upon clay or other heavy soils. The soil which makes the worst and most sticky mud when allowed to become saturated with water makes the hardest and most impervious surface when well maintained.