EARTH, SAND-CLAY, AND GEAVEL ROADS. 23 



inches wide. Then make the initial trip with the point of the blade 

 cutting about 18 inches outside of the stake line and the outside 

 rear wheel of the machine against the face of the furrow. The 

 material loosened by the first furrow then will escape under the blade 

 in a ridge just inside the stake line. 



(3) Readjust the machine so that when the outside horses follow 

 the initial furrow in making the second trip the blade will cut a 

 new furrow of somewhat less width than the first and the outside 

 rear wheel will follow the face of the new furrow. Then make 

 successive trips with the machine adjusted in this way until the 

 outside edge of the side ditch is approached, except that after each 

 two trips it is well to rest the team by readjusting the blade and 

 pushing the loosened material over toward the center of the road. 

 For this latter work the blade may be set at a greater angle with the 

 road, and the heel should be lowered and the point raised, so that 

 the cutting edge will conform closely to the crown of the road while 

 the machine is in operation. 



(4) Repeat the above-described operation, omitting the stakes and 

 beginning about 18 inches farther from the center each time, until 

 the side ditches are excavated to the required depth and the road is 

 approximately to the required cross section. 



(5) Bring the outside faces of the side ditches to a uniform slope 

 by making one or two trips of the machine with two wheels, one 

 front and one rear, on the bank and the cutting edge of the blade 

 against the slope. 



(6) Make several trips over the road, cleaning out the ditches and 

 smoothing up the surface. The last few trips should be made with 

 the blade reversed, as this method tends to produce a better com- 

 pacted surface. But, in any event, it is necessary that during the 

 first few months after the grading is completed the road surface 

 should be kept smooth while it is being compacted under traffic. To 

 do this may require frequent use of the grading machine or the drag. 



Plate II shows a model constructed by the Office of Public Roads 

 and Rural Engineering for the purpose of illustrating in small space 

 the successive steps involved in grading a road through level country 

 by means of a grading machine. 



The method of operating a grading machine described above 

 necessarily will have to be modified at times in order to meet special 

 conditions. Where, for example, the ditch area is covered with heavy 

 sod or contains a number of large roots, it may be very desirable to 

 plow this area and cut the roots with an ax before using the grading 

 machine. If this is done the plow furrows should be turned toward 

 the center of the road and the line of the initial furrows should be 

 controlled by two rows of stakes as described above. If the sod is 



