ROADS AND BRIDGES 



307 



Figure 183. Bounded ditches. 



THE ROADBED 



Draining the roadbed. Almost any kind of material, 

 except loose gravel or sand or soft peat, will make a hard 

 road under a roof which keeps off the rain. On the other 

 hand, no material except rock or other very hard sub- 

 stance will make a satisfactory road surface if it is kept 

 constantly wet by rain or by ground water. Water 

 which falls upon the roadbed should be conducted side- 

 ways into the roadside ditch by having the roadways 

 slope from the center to 

 the sides. The water flow- 

 ing from the surface of the 

 road to the side ditch, and 

 flood water flowing from 

 adjacent lands upon the roadway, should be taken care 

 of by ample ditches. Where ground water rises within 

 a few feet of the surface beneath roads it should be 

 carried off by means of tile drains. Figures 181 to 189 

 illustrate roadside ditches of various forms. In 

 Figure 181 is shown the earth road as rounded up with 



the reversible road ma- 

 chine. The ditches being 

 beside fences, their outer 

 banks are often left ver- 

 tical. The reversible ma- 

 Figure 184. Roadway with rounded ditch , . , - . . 

 on left side and neat crop growing nearly chine Can DC SO adjusted 



that both slanting and 

 rounded ditches can be 

 made as shown in Figures 182, 183 and 184. Where the 

 slush or drag scraper is used to make roadside ditches 

 they are left in awkward form, as shown in Figure 185. In 

 many cases the reversible machine can be used to finish 

 the road and ditches thus made, leaving them much in the 

 form shown in Figure 181. (See also Figure 207.) At 

 Figure 187 is shown a cross-section of a large drainage 



to the wheel tracks. On right side the 

 ditch has a steep bank. Outside the bank 

 and between the bank and the wheel track 

 are areas uncouth with large weeds. 



