538 IOWA DEPARTMENT OF AGRICULTURE. 



hauling and to three hundred and fifty million miles of other travel per 

 annum. The cost of this traffic to the State, based on common wages, 

 would probably be between forty and fifty million dollars per annum. 



In our study of the good roads problem in Iowa we find nothing of greater 

 importance than the proper drainage of the roads. Figure 1 is a view show- 

 ing a poorly drained earth road, and illustrates the fatal effect or poor 

 drainage. In fact, good drainage may be considered the first essential in the 

 construction of good roads. No matter how impervious any kind of soil 

 may be, we would find by pouring water upon it that it has capacity to 

 absorb a very large percentage of water. The presence of water in excess 

 in soil changes it to a soft and even semi-liquid condition in which it is in- 

 capable of supporting loads. Removing this water will put ordinary soils 

 into good condition to carry loads. In fact, during considerable portions of 

 each year, when the weather is dry, our earth roads are in very excellent 

 condition. 



Fig-. 3— Vi3w Illustrating: Well Graded Earth Road ia Carroll County, Iowa. 



Note the crowning of the road and the well constructed side ditches extending with a con- 

 tinuous grade to the river in the distance. 



To secure proper drainage of any road three systems of road drainage 

 must be provided, which may be respectively designated, subdrainage, 

 side-drainage, and surface drainage. 



Sub-drainage. — A good foundation is absolutely essential to the construe 

 tion of a good road and a good foundation can not be secured where the 

 soil on which the road is built is in a wet, miry condition. In Carroll 

 county a road has been built across a low stretch of land, which has been 

 repeatedly covered with gravel at considerable expense with the result that in 

 a short time the gravel disappeared and the road resumed its wet condition. 

 Under such conditions the only proper remedy is to sub- drain bylines of 

 tile laid on one or both sides of the road, according to circumstances. 



In many instances in some sections of Iowa we find it necssary to con- 

 struct roads through ponds. In such cases the only proper method to be 



