540 IOWA DEPARTMENT OF AGRICULTURE. 



carried out and the side ditches serve as a series of ponds to retain the sur- 

 face water. We believe surveys should be made of every road and profiles 

 constructed, giving the grades not only of the center lines of the road, but 

 also of the side ditches. In the low points of the ditches outlets should 

 always be provided so that water will not stay in any part of the side ditch. 

 Surface-drainage.— ¥\%Mre 4 also illustrates the crowning of a properly 

 constructed road to throw the surface water to side ditches, and figure 4 is 

 a view of a macadamized road in New York State also illustrating the 

 proper form of side ditch and crowning of the road. Our advice is that on 

 earth roads this crowning should be about one inch per foot. In the origi- 

 nal construction of any road the crown should be made greater than is con- 

 sidered permanently necessary, for the tendency is for the road to wear flat. 



Figr. 6— Reinforced Concrete Arch Culvert, Greene County, Iowa, Span Five 



Feet. 



In the maintenance of our earth roads the principal trouble with a prop, 

 erly constructed road is in maintaining proper surface drainage. During 

 and immediately after the rains the surface of the road cuts up from the 

 horses' feet and the wheels so as to make a series of local depressions and 

 ruts which retain the water. From these ruts and depressions it soaks into 

 and softens the road until the well-known muddy and impassable condition 

 results. In the case of earth roads which are not provided with any perma- 

 nent covering this can not be wholly avoided, and can only be kept within 

 reasonable bounds by constant care in maintenance. The maintenance of 

 an earth roadjshould be directed to maintaining the crown, keeping the road 

 surface smooth and the side ditches open. Whenever the road gets in rough 

 condition it should be gone over with a harrow, a steel rail, or light scraper 

 so as to reduce the lumps and again make it smooth enough to shed water. 



