MOTOR NOTES.

Putaruru Press, 7 June 1928, Page 3

MOTOR NOTES.

CONCRETE ROAOING COSTS,

LOWER THAN BITUMEN. Superior Qualities of Concrete. In view of the likelihood of much more modern road surfacing being carried out locally, it is as well to note that in at least one instance concrete has proved cheaper than bitumen. This is the case with a contract just let for a section of the main south road between Chaney’s and the Styx bridge, Marlborough. For heavy traffic, concrete pavements practically all the world over are recognised as superior to bituminous paving. As a general thing, in the past the cost of concrete has been so much higher than bitumen that it has been more economical to lay bitumen except where the traffic is so heavy that no other type than concrete is considered likely to stand up to it. Where the cost of a good quality concrete pavement approaches that of a bituminous type the main arguments in favour of the latter vanish. According to an announcement in Board and Council, the tender for a concrete pavement for the southern road in question was £17,238 for the 2.9 miles. The lowest tender for hotmix was £I6OO above this figure. In both cases the tenders included all preparations and other work necessary.

The price works out at 11s 3d per square yard of the 18-foot concrete pavement, but as the job includes bituminous macadam shoulder a yard wide on each side of the concrete, the actual cost of the concrete is slightly below this figure. It is worth noting that, according to cost sheets presented to the Wellington City and Suburban Highways Board, the cost of 3S-inch 18-foot paving on the main road at Upper Hutt ran out at 11s 9.39 d per square yard, no bituminous shoulders being provided in this case. Christchurch, under the new contract, is thus due to receive a concrete pavement twice as thick for less money, and with the bituminous shoulders it will have a surface 24 feet wide, instead of 18 feet wide, as at Upper Hutt. On a cubic yard basis the cost of the Christchurch concrete pavement (bituminous shoulders thrown in) runs out at about £3 ss. On the same cubic yard basis the Upper Hutt paving (no shoulders) runs out at about £5 17s 6d.

The Christchurch tender is, of course, exceptionally low. The 7 i miles of concrete paving from Auckland to Henderson cost close on £1 per square yard. More recently the concrete laid south of Auckland on the main road out to Papakura has run at 15s per square yard.

If contractors can be found ready to lay concrete pavements for less that the cost of hotmix, and pavements twice as thick at that, the wisdom of continuing with hotmix naturally becomes a very open question. Concrete paving, apart from price, has several advantages over hotmix. Cement is a local product, and a conj Crete pavement does not mean sending large sums of money abroad for j material produced in a foreign country—all the material required is produced locally. Hot-mix paving can be laid only in the dry summer period. Concrete paving can be proceeded with over a much longer period of the year. Bituminous paving, being black in colour, has a very low visibility at night, and the risk of accident in night driving is thus greatly increased. Concrete, being light in colour, gives even better visibility at night than macadam. It has the disadvantage of glare in brilliant sunshine, but this glare is not such as to create an accident hazard, as the low night visibility on bitumen undoubtedly is.