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Elementary Principles of Agriculture 



Not only this, but side drains should be large enough 

 to carry off all water without washing, and graded to 

 prevent the formation of pools on the sides. The water- 

 table should be kept well below the surface of the road. 



Fig. 181. Cross sections of two good forms for earth roads. The lower section 

 can be made with a road machine, and both sections can be maintained 

 with a split-log drag so that water will run off easily and quickly. 



Fig. 182. Cross section of a road showing the result of improper construction 

 and drainage. Note that the center of the road has become the lowest part 

 and that water may collect on the surface, making the road practically 

 impassable. 



Fig. 183. Cross section of road, showing clay cover on "deep" sand subsoil 





Fig. 184. Cross section of Macadam road, showing a compact foundation of 

 earth supporting a solid and durable stone surface. 



Fig. 185. Transverse section of Telford road with Macadam surface. 



Suitable culverts should be provided to dispose of storm 

 water. These should have sufficient fall from the upper 

 to the lower side to wash out all sediment. 



409. Surfaced Roads. Different kinds of material are 

 used in surfacing roads. In sections where suitable gravel 



