PROCEEDIN'GS OF SECTION H. 655 



the metal is consolidated by wheel traffic, sufficient grit will be abraded 

 from metal without the addition of anything else, pro\'ided the surface 

 is properly tended. This is the system of Macadam. 



Under modern conditions and requirements roads carrying heavy 

 traffic Avould have to be made with a Telford base if a heavy roller 

 were not available. With a heavy roller a foundation Sin. thick of 

 4in. metal can be consolidated so as to stand heavier loads than the 

 standard Telford foundation ; but for country roads the true macadam 

 road is quite satisfactory. The distinguishing feature of a macadam 

 road as now known strictly speaking lies in the use of metal broken 

 to a gauge whether 4in. or 2in., no matter whether consolidated in 

 ■one layer or two, or three, so long as there is no set foundation. 



The average cost of making a macadam road in Adelaide is as 

 iollows : — Per chain of 22ft. 6in. between watertables : 



FiKST-CLAss Road — £ s. d. 



Excavation — 55 cub. yds. at Is. 6cl 4 2 6 



Grading and rolling formation — 165 sq. yds. at Id 13 9 



Bottoming (12in., loose)— 55 cub. yds. at 4s. 8d. supply + 4d. 



spreading + 2d. rolling = os. 2d 14 4 2 



Blinding (chippings) — 11 cub. yds. at 2s. 6d 1 7 6 



Intel-mediate coat (4^in., loose) — 21 cub. yds. at 4s. 9d. + 4d. 



+ 9d. = 5s. lOd '. 6 2 6 



Blinding— 2 cub. yds. at 3s 6 



Top coat— 21 cub. yds. at 4s. 9d. + 4d. + Is. = 6s. Id 6 7 9 



BlincUng — 2 cub. yds. at 3s 6 



Total cost per chain £33 10 



Second-class Road — 



Excavation — 37 cub. yds. at Is. 6d 2 15 6 



Grading and rolling fomiation— 165 sq. yds. at Id 13 9 



Bottoming (8in., loose)— 37 cub. yds. at 5s. 2d 9 11 1 



BUnding — 7 cub. yds. chippings at 2s. 6d 17 6 



Top course C4^ in., loose) — 21 cub. yds. at 6s. Id 6 7 9 



Blinding— 2 cub. yds. at 3s 6 



Total cost per chain £20 11 



Third-class Road — 



Excavation— 20 cub. yds. at Is. 6d 110 



Grading and rolling - 165 sq. yds. at Id 13 9 



Metal (6in.. loose) —28 cub. yds. at 6s. Id 8 10 4 



Blinding- 3 cub. yds at 3s 9 



Total cost per chain £11 3 1 



The cost of re-sheeting any one of these roads would be that of 

 renewing the top coat of the first or second class road, viz., £6 13s. 9d. 

 per chain. Now the streets in which the dust nuisance is to be com- 

 bated it is evident will not be those whi'ch are watered regularly. They 

 will be comparatively light traffic roads, and subject to re-sheeting 

 once in about five years. The average cost of this sheet per annum 

 would therefore be not less than £1 6s. 9d. per chain, or 2d. per square 

 yard per annum. 



The ordinary macadam road is a gTeat dust-producer, and to over- 

 come this evil many minds have been at work. Almost all have started 



