HIGHWAY CONSTRUCTION 



Although often omitted, the end sections should be protected 

 with a masonry or timber bulkhead. The foundation of the bulk- 

 head should be deep enough not to be disturbed by frost. In con- 

 structing the end wall, it is well to increase the fail near the outlet 

 to allow for a possible settlement of the interior sections. When 

 stone and brick abutments are too expensive, a fair substitute can 

 be made by setting posts in the ground and spiking plank to them. 

 When planks are used, it is best to set them with considerable inclina- 

 tion towards the roadbed to prevent their being crowded outward 

 by the pressure of the embankment. The upper end of the culvert 

 should be so protected that the water will not readily find its way 



Fig. 19. 



along the outside of the pipes, in case the mouth of the culvert should 

 become submerged. 



When the capacity of one pipe is not sufficient, two or more 

 may be laid side by side as shown in Fig. 19. Although the two 

 small pipes do not have as much discharging capacity as a single 

 large one of equal cross-section, yet there is an advantage in laying 

 two small ones side by side, since the water need not rise so high 

 to utilize the full capacity of the two pipes as woula be necessary 

 to discharge itself through a single one of large size. 



Iron Pipe Culverts. During recent years iron pipe has been 

 used for culverts on many prominent railroads, and may be used on 

 roads in sections where other materials are unavailable. 



In constructing a culvert with cast-iron pipe the points requiring 



