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 1J 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, b} T 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. 507, " The Road Drag and How it is Used." 
