Good results with the drag depend upon choosing the proper time to drag and upon doing the work in the right way when using the drag. The best time to drag is as soon after a rain as the road has dried out enough to pack under traffic. If the work is done while the road is too wet, the first vehicles traveling the road after it has been dragged will make ruts and to a considerable extent offset the good done by the drag. If the road is too dry, the drag will not smooth the irregularities. A little observation will be required to determine the proper time for dragging on any particular soil, but usually after a rain or thaw there is a period lasting a day or two when conditions are about right. [Illustration: Fig. 13.--Road Drag] The drag is used merely to restore the shape of the surface and to do so a small amount of material is drawn toward the middle of the road. But there must not be a ridge of loose material left in the middle after the work is completed. Some patrolmen start at one side of the road and gradually work across the road on successive trips, finally finishing up at the side opposite that at which the start was made. The next dragging should start on the opposite side from the first if that method is followed. By shifting his weight on the drag, the operator can adjust the cutting edge so that very little loose material is moved crosswise of the road and that is the proper method to pursue. In that case no ridge will remain at the middle of the road. If a slight one is left it should be removed by a final trip with the drag. In addition to the dragging, weeds must be cut along the road about twice a year, the ditches must be kept cleaned 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.