Farm Roads on Strong Soils. 89 



marked out. The cross culvert and cross under-drains should 

 then be fixed and constructed, or laid ; the floor or invert of 

 every culvert or drain should be 5 feet below the surface of the 



road when finished, in order that the longitudinal drains under 

 the roadway be at least 4 feet deep. The ditches or watercourses 

 with which the culverts communicate should be cleared out or 

 deepened to a sufficient depth to free the culverts and drains of 

 standing water. The side ditches C K, and under-drains D, 

 should then be dug. The earth thrown out of the side ditches will 

 serve to form the raised side spaces of the road H, care being 

 taken that a good shoulder be formed at B to receive the 

 metalling. 



The earth thrown out of the under-drain D should be returned 

 into it after the pipes are laid and closely trodden in. If a part 

 of the metalling used for the foundation be mixed with it the 

 base of the road will be kept drier during construction. No 

 advantage is gained by the mixture after completion. 



In shaping the base to a convex form for the metalling a small 

 quantity of soil will have to be taken off the sides at E, and 

 this soil, with the surplus which will remain out of the under- 

 drains, will serve to fill up hollows and irregularities in the for- 

 mation level. Where high-backed lands are crossed the labour 

 and cost of formation will be considerably increased. 



The approximate cost of forming roads for metalling per chain 



will be as follows : — 



s. d. 



Digging side ditches, 18 inches deep, 30 inches at top, and 



12 inches at bottom, say 13 cubic yards per chain, at 3f/. 



per yard 3 3 



Digging and filling under-drains, 4 feet deep, 8 rods per 



chain, at 6^cZ. per rod 4 4 



Pipes for same, 135 per chain, at 20s. per 1000 2 9 



Laying and treading in 6 



Forming base for metalling, shifting earth, levelling, and 



finishing side spaces, seeding same, &c 3 9 



14 7 

 Add for proportion of culverts and contingencies 10 per cent. 1 5 



Total cost of formation per chain 16 



