58 BULLETIN 463, U. S. DEPARTMENT OF AGRICULTURE. 



per square yard. These costs include labor only, and if fuel for 

 the roller and depreciation were considered, the average cost probably 

 would approximate 1| cents per square yard. 



ROAD MAINTENANCE. 



METHODS OF MAINTENANCE. 



As soon as a road is constructed, the action of traffic and the 

 weather begin to destroy it. and to counterbalance the effects of 

 these deteriorating influences it is necessary to institute some sys- 

 tem of maintenance. There are two common ways of maintaining 

 a road. One is to make periodic repairs or renewals after sections 

 of the road have been practically destroyed : the other is to employ 

 a system of continuous maintenance under which all injuries to the 

 road are repaired as fast as they occur. For the types of roads which 

 have been discussed the system of continuous maintenance is much 

 more preferable from practically every standpoint, and that system 

 alone will be discussed here. 



THE ROAD DRAG. 1 



The road drag is a simple and inexpensive device for maintain- 

 ing certain types of roads which, when wet, become rutted under 

 traffic but which become firm on drying out. It is useful also in pro- 

 ducing a smooth and uniform surface on newly constructed roads of 

 earth, earthy gravel, or any similar material. Figures 23 and 24 show 

 typical designs for road drags made, respectively, of a split log and 

 of sawed timber, and drags made in accordance with either design 

 may be operated with two horses. 



Properly used at the right time the drag performs four distinct 

 functions: first, by moving at an angle with the traveled way; it 

 tends to produce or preserve a crowned cross section ; second, if used 

 when the surface is comparatively soft, it tends to reduce irregulari- 

 ties in the road, by moving material from points which are relatively 

 high to those which are relatively low ; third, when used after a 

 rain it accelerates the drying out of the road by spreading out pud- 

 dles of water and thus exposing a greater area to evaporation: 

 fourth, if the surface material is in a slightly plastic state, dragging 

 smears over and partially seals the so-called pores which naturally 

 occur in earthy material, and thus makes the road surface more 

 nearly impervious to water. 



To obtain the best results dragging should be done only when the 

 surface of the road is sufficiently moist for the material moved by the 



1 See Farmers' Bulletin No. 597, " The Road Drag and How it is Used." 



