402 STATE BOARD OF AGRICULTUEE. 



soft and muddy. The Telford roads are much better than the McAdara roads, 

 especially where the McAdam roads have been built over low ground with no 

 more provision for drainage than given in the original directions of McAdam, 

 simply because Telford prescribes a better drainage for the road foundation in 

 his directions. 



Thus it is seen that thorough drainage of roads has always been and still is 

 of great importance in road construction, and, second, that the best road cover- 

 ings cannot be made entirely impervious to water. 



METHODS OF DKAIXIXG ROADS. 



The next questions that naturally arise are regarding the methods of drain- 

 ing roads. The methods of the great English road builders have been fully 

 stated, but on account of the great cost of these roads, for the time being at 

 least, we Avill have to content ourselves with cheaper roads. Whatever system 

 of road making is adopted, it should be one that will keep our roads constantly 

 improving, and one that does not demand very costly annual improvements to 

 keep them steadily growing better. It is a well known fact that if means are 

 provided for the escape of water, even though no broken stone, gravel, or other 

 road covering be applied, the road will be greatly improved. A dry, smooth 

 road on clay or loam (roads on dry sand not referred to in this article) is always 

 in a good condition, and the nearer dry a road on heavy soil can be kept the 

 better will it be. The common means resorted to for removing the water is by 

 turnpiking, ditching, and by under-draining. These three methods we will 

 consider somewhat in detail. 



TUENPIKING 



is performed by excavating ditches at the sides of the road and throwing the 

 earth obtained from these into the center, forming an elevated ridge on which 

 the roadway is formed. The roadway being elevated above the side channels 

 the water passes from it partly by passing through the surface of the road and 

 working its way through the ground until it roaches the side channels, and 

 partly by running directly down the slopes of the roadway into the side chan- 

 nels. The efficiency of the turnpike depends upon its dryness ; for when heavy 

 soils are saturated with water they become soft and incapable of supporting a 

 heavy load, consequently it becomes evident that the surface of the turnpike 

 should be made of such shape as to allow as little water as possible to permeate 

 the surface, and it should convey as large a per cent as the conditions will allow 

 directly to the side channels, which should be made so as to convey the water 

 that passes into them completely and rapidly away. 



SLOPE OF THE ROADWAY. 



The slope that may be given the surface depends somewhat upon the nature 

 of the soil and the character of the travel that passes over the road. 



The steeper the surface the less water will it absorb, but if it be made too 

 steep, the water passing over it will wash much earth into the side channels 

 thus rendering them comparatively useless as well as endangering the safety of 

 the travelers who drive near the side of the road. The exact slope that will 

 best suit all cases cannot definitely be stated, but experience has shown that a 

 rise of one inch for every three feet measured horizontally answers the required 

 conditions very well for the road bed. The slope of the side of the road to the 

 ditches should be little more than one inch to the foot, while a steeper slope. 



