FREE BOOKS

Author's List




PREV.   NEXT  
|<   55   56   57   58   59   60   61   62   63   64   65   66   67   68   69   70   71   72   73   74   75   76   77   78   79  
80   81   82   83   84   85   86   87   88   89   90   91   92   93   94   95   96   97   98   99   100   101   102   103   104   >>   >|  
ned out and culverts open. All of the maintenance for 10 miles of earth road can be accomplished by one man giving his entire time to the work, and that is the only method that has proven adequate to the problem. EARTH ROADS IN ARID REGIONS In areas where the rainfall is less than 18 inches per year, and especially where it is 10 inches or less, an entirely different road problem exists. The effect of precipitation is of significance primarily from the standpoint of erosion, and the design of cross section and ditches and the culvert provisions are entirely different from those necessary in humid regions. Frequently the rainfall in semi-arid regions will be seasonal and provision must be made to care for a large volume of water during the rainy season, but, in general, road design is adapted to prevention of erosion rather than to elimination of ground water effects, or the softening effects of surface water. Generally the rainy period does not last long enough to warrant expensive construction to eliminate its general effects. In fact, the saturation of the soil is more likely to be a benefit than otherwise. Earth roads are likely to be satisfactory except where the traffic is sufficient to grind the surface into dust to such an extent that an excessive dust layer is produced. In such locations the problem is one of providing a durable surface unaffected by long continued dry weather. Grade reduction will have the same importance as in humid areas and will be carried out in the same way. Maintenance will consist in repairing the damage from occasional floods and in removing or preventing accumulations of drifting sand or dust. Crude petroleum oils have been satisfactory for maintenance in such locations when used on stable soils. =Value of Earth Roads.=--The serviceability of the earth road depends to a large extent upon the care exercised in its maintenance. The only part of earth road construction that is permanent is the grade reduction. The cross section that is so carefully shaped at considerable cost may flatten out in one or two years, especially if the road goes through unusually wet periods. Traffic will continually seek a new track during the period when the road is muddy and is as likely to cross the ditch to the sod near the fence as to use any other part of the road. Continual and persistent maintenance is therefore essential to even reasonable serviceability. At best the earth road wi
PREV.   NEXT  
|<   55   56   57   58   59   60   61   62   63   64   65   66   67   68   69   70   71   72   73   74   75   76   77   78   79  
80   81   82   83   84   85   86   87   88   89   90   91   92   93   94   95   96   97   98   99   100   101   102   103   104   >>   >|  



Top keywords:

maintenance

 

surface

 

effects

 
problem
 
serviceability
 

regions

 
section
 

erosion

 

design

 

general


satisfactory
 

extent

 

locations

 

reduction

 

construction

 
period
 

inches

 

rainfall

 

permanent

 
petroleum

exercised

 
depends
 

stable

 

culverts

 

preventing

 

carried

 

Maintenance

 
importance
 

consist

 

repairing


accumulations

 

drifting

 

removing

 

floods

 

damage

 

occasional

 

Continual

 

reasonable

 

persistent

 

essential


flatten

 

considerable

 

carefully

 

shaped

 

weather

 

periods

 
Traffic
 

continually

 

unusually

 

providing