HIGHWAY CONSTRUCTION 



particular attention are (1) tamping the soil tightly around the pipe 

 to prevent the water from forming a channel along the outside, and 

 (2) protecting the ends by suitable head walls and, when necessary, 

 laying riprap at the lower end. The amount of masonry required 

 for the end walls depends upon the relative width of the embankment 

 and the number of sections of pipe used. For example, if the em- 

 bankment is, say, 40 feet wide at the base, the culvert may consist of 

 three 12-foot lengths of pipe and a light end wall near the toe of 

 the bank; but if the embankment is, say, 32 feet wide, the culvert 

 may consist of two 12-foot lengths of pipe and a comparatively heavy 

 end wall well back from the toe of the bank. The smaller sizes of 

 pipe usually come in 12-foot lengths, but sometimes a few 6-foot 



Broken Stones 

 or Bricks 



Fig. 20. Section of Pipe Culvert 



lengths are included for use in adjusting the length of the culvert 

 to the width of the bank. The larger sizes are generally 6 feet long. 



EARTHWORK. 



The term "earthwork" is applied to all the operations per- 

 formed in the making of excavation and embankments. In its 

 widest sense it comprehends work in rock as well as in the looser 

 materials of the earth's crust. 



Balancing Cuts and Fills. In the construction of new roads, 

 the formation of the roadbed consists in bringing the surface of the 

 ground to the adopted grade. This grade should be established so as 



