ROAD-MAKING. 197 



the case of a narrow road, the traffic being confined to the centre and in 

 one track, the wear upon that road is more severe than upon one with a 

 wider surface, where the traffic is not confined to one track, but is spread 

 over the surface. One great advantage in a wide road is, that the sun 

 and wind have a greater influence in keeping the surface dry. 



The form given to a road is a subject worthy of consideration, as 

 a great diversity of opinion exists regarding it. Many think the best 

 form is one with a considerable curve, while others are of a contrary 

 opinion. So far as my own experience goes, I would recommend that 

 roads made in plantations, where the traffic is only occasional, should be 

 made with a slight curve, as then they are always better kept dry ; but 

 where there is any considerable traffic upon roads, they should be made 

 nearly level, having a slight curve in the centre. On this subject Mr 

 Macadam remarked, in giving his evidence before a Committee of the 

 House of Commons :* " I consider a road should be as flat as possible, 

 with regard to allowing the water to run off at all, because a carriage 

 ought to stand upright in travelling as much as possible. I have 

 generally made roads three inches higher in the centre than I have 

 at the sides, when they are eighteen feet wide ; if the road be smooth 

 aud well made, the water will run off very easily in such a slope." In 

 answer to another question, he states : " When a road is made flat, 

 people will not follow the middle of it as they do when it is made 

 extremely convex. Gentlemen will have observed that in roads very 

 convex travellers generally follow the track in the middle, which is the 

 only place where a carriage can run upright, by which means three 

 furrows are made by the horses and the wheels, and water continually 

 stands there ; and I think that more water actually stands upon a convex 

 road than on one which is reasonably flat." 



Having chosen the line of route for a, farm-road, the next important 

 point is to secure the foundation of the road dry. For this purpose it 

 should be drained on each side, as shown in fig. 72. 



The drains a a should be made first ; they should be cut in the 



Fio. 72. 



ordinary way to a depth of four feet from the surface. In some soils a 

 less depth might answer the purpose, but as the object of these drains 



* 



* Parliamentary Kcport on the Highways of the Kingdom, 1812, p. 22. 



