CHAPTER XXIV 

 EARTH ROADS 



Extent. Of the total mileage of roads in the United 

 States, about 2,000,000 miles are unimproved, or earth 

 roads. It is evident that a large percentage of these roads 

 will remain unimproved for a long time, and for this reason 

 earth roads are worthy of the most careful attention. By 

 the term " earth roads" is meant roads made of native soil 

 and whose surface is loam or clay. Obviously the earth 

 road is the cheapest form of road. It is possible to construct 

 a fairly good road out of native soil, and such a road in most 

 cases furnishes the very best foundation for an improved 

 road with a hard surface of sand or gravel. 



Construction of an Earth Road. The subject of earth 

 roads naturally divides itself into two divisions, earth-road 

 construction and earth-road maintenance. The first applies 

 to the preparing, constructing or building of the road, and the 

 last to its maintenance or repair. 



Drainage. It is often stated that the construction of 

 earth roads consists primarily in providing adequate drain- 

 age. When considered in the broadest sense, drainage 

 would include not only underdrainage, but also surface 

 drainage. Underdrainage is quite necessary in any kind of 

 road, and especially in an earth road, and if not provided 

 naturally it should be provided artificially. In constructing 

 earth roads it is desirable to maintain as hard a surface as 

 possible with the materials used, and water tends to soften 

 them. The supporting power of earth depends largely upon 

 the dryness of the soil. A good surface may be prepared, yet 



147 



