Fig. 12.—Tractor-grader Outfit
Use of Blade Grader.—Heavy blade graders designed to be drawn by a tractor are suitable for shaping the earth road. Some of these have blades 12 feet long and excellent control for regulating the depth of cutting. Often two such graders are operated tandem. These machines have a device which permits the operator to steer the grader independently of the tractor. Thus the grader can be steered off to the side to cut out the ditches, while the tractor continues to travel on the firm part of the road. Earth moved with the blade grader is usually fairly free from large lumps and can readily be smoothed to a satisfactory surface for the use of traffic. The sods and weeds will be drawn into the road along with the earth just as they are when the elevating grader is employed. Precaution must therefore be taken to eliminate them before the vegetable matter decays, and to smooth the surface for the use of traffic.
Costs.—The cost of shaping an earth road in the manner described above will vary through rather wide limits because the nature and amount of work to be done varies so greatly. Some roads can be graded satisfactorily for $300.00 per mile, while others will cost $700.00. But $425.00 per mile may be taken as an average for blade or elevating grader work plus a moderate amount of grade reduction in the way of removing slight knolls. For the amount of grade reduction necessary in rolling country, followed by grader shaping, $1000.00 to $1800.00 per mile will be required. The method is not adapted to rolling country where the roads are undulating and require some grade reduction on every hill. For hilly roads one of the methods described for grade reduction will be required and the cost will obviously depend upon the amount of earth moved. Averages of cost figures mean nothing in such cases as the cost may reach $10,000.00 per mile, or may be as low as $2000.00 per mile.
Maintenance.—Regardless of the care with which an earth road has been graded, it will be yielding and will readily absorb water for a long time after the completion of the work. The condition of the surface will naturally deteriorate rapidly during the first season it is used unless the road receives the constant maintenance that is a prerequisite to satisfactory serviceability. The road drag is generally recommended for this purpose, and if a drag is properly used it will serve to restore the shape of the surface as fast as it is destroyed by traffic.
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.
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.