ROAD CONSTRUCTION 97 



is also clear that for many centuries to come, large areas of our country 

 can hope for nothing better than good natural roads. 



The faults of our natural roads which could easily be remedied are 

 mainly these : 



1 The roads are too narrow and too high in the center, and on account 

 of their narrowness the wheels all run in die same track and the extreme 

 curvature of the road bed compels the wheels to run on the edge instead 

 of the surface of the tires, the combination of the two faults causing the 

 formation of deep ruts ; 



2 Loose stones are allowed to remain in the roads and the work of 

 repair is not directed toward keeping the surface smooth ; 



3 Insufficient attention is given to the construction of drains and 

 culverts. 



Road Construction 



The experience of over 2,000 years has shown conclusively that there 

 are two essential points to be aimed at in the construction of a perfect 

 road ; 



i A hard, smooth, waterproof surface ; 



2 A thoroughly dry foundation. 



These principles were known to the Romans three hundred years 

 before Christ and used in the construction of their best highways. 



The surface of a good road must be of sufficient strength to resist the 

 wear and tear of traffic, and smooth enough to prevent undue strain and 

 wear on vehicles. In connection with this the soil beneath must be made 

 dry and kept dry. Therefore the subject of road drainage is as important 

 as that of road metalling. 



The best road covering is composed of angular fragments of some 

 stone which will grind on the surface into a dust, which when wet will 

 bind or in a measure cement the fragments together, so that water will 

 not penetrate. The angular form is essential to make the fragments 

 interlock. The sizes should be quite uniform, except that the suiface 

 layer may consist of fragments different in size from those in the bottom 

 course. 



The total thickness of this metalling must be at least six inches on a 

 natural soil foundation. The fragments should not exceed two and a 

 half inches in diameter, and should be rolled in two separate courses 

 with a heavy steam roller until the surface is absolutely firm. This is 

 the Macadam system. 



