Earth Roads. 455 



562. Utilizing the Old Road as a Road-bed. In cases 

 where the grade docs not require changing and where nat- 

 ural under-drainage is adequate the old road-bed may be 

 utilized in its already tramped and packed condition upon 

 which to build the new road. This may be fitted with the 

 road machine by throwing the loose and uneven portion of 

 the surface outward to form the shoulders. Then if there 

 are still low places these should be filled in and thoroughly 

 packed with the roller, the use of which is necessary even 

 where no leveling is needed, in order to discover any soft 

 spots, quite certain to exist, and in order to give the foun- 

 dation a more thorough packing than the wagons have se- 

 cured. 



563. Preparing the Road-bed a Year or More in Advance, 



It will generally be found advantageous to get the road-bed 

 into proper shape to receive the surfacing material, whether 

 this be gravel or crushed rock, a year or more in advance, 

 utilizing jthe weathering of rains, the frost of winter and 

 the traffic to settle the road-bed, but directing and assisting 

 these agencies by a timely and judicious use of the harrow, 

 road machine and roller. It is particularly important to 

 allow time to intervene where there has been much filling 

 necessary. 



564. Roads on Gravelly Loam. Where the soils are a 

 gravelly loam the best earth roads are possible. The reason 

 for this is found in the fact that a gravelly loam is made up 

 of large and small grains in such proportions that when 

 they are thoroughly worked and compacted the coarser sand 

 particles work in between the gravel, and the fine clay par- 

 ticles between those of sand, in such a way that there is left 

 almost no open space ; under these conditions the water is 

 shed the most rapidly and completely so that the road is less 

 liable to soften under the travel over it and it is less liable 

 to be injured by frost. 



565. Roads in Fine Clay Soil. Where the soil is a fine ad- 

 hesive clay it is hardly possible to make a good road with- 



