ROAD MAKING

Taranaki Daily News, Volume LIV, Issue 275, 17 May 1912, Page 4

ROAD MAKING

NECESSITY FOR A GOD!) SURFACE.

At the Royal Institution. London, Sir John 11. C. Macdonald, K.R.S.. member of the Road Board, recently gave a most interesting address on the past, present and future of our roads, ft is, of course, a commonplace with those who have taken the trouble to ascertain the facts that the dust nuisance is no new development. Bob Acres travelled to Bath "with a tail of dust as long a« the Mall." On the Bath road, over which 140 mail coaches passed per day, pumps were provided every two miles to provide water for laying ,-this dust. Then, as now, there were those who objected to apeed as an evil in itself. Sir if. Parnell, the well-known authority on road 3, writing in 1838, said that speeds of 25 to 30 miles an hour could not be justified, and that as there was no advantage in exceeding 10 miles an hour, railway transit could not possibly pay, and thus "the cheapef method of using horse power will be adopted." In the eighteenth century ruts were sometimes 4ft deep, and, indeed, it was not considered necessary to fill them in til! the axles grounded/ In it took two hours to drive from Kensington to Westminster. The lecturer pointed out that the so-called macadam road as now made was a misnomer. Macadam's ruling idea was to keep water out of the road crust. He broke his stones to l%in guage, and required that ■they should be consolidated by the traffic. With the advent of the steam roller, the use of water binding became general, greatly to the disadvantage ol the road. So long as a road thus made, was merely damp, the lecturer said, it was fairly satisfactory, but in wet weather water could get in where it had come out, and the mud-soup originally used in binding the road was reproduced. In dry weather the binding was reduced In bulk and loosened by the loss of water. The stones could therefore move, and were picked out of the surface, leaving holes for the entry of water. Roads being thus defective "ab initio," were incapable of withstanding the return of traffic to the highways, and a new method of construction had become imperative, but, fortunately, this promised to be cheaper in the end than the old. The Thames Embankment, the speaker stated, was at one time one ol the worst in the country. Last year, however, it never required watering during the whole of the long drought, although as many as 1(J00 vehicles per hour passed over it. Any water forming on it dried off quickly without forming mud, and in fine weather there was practically no dust.

In another ten years, the speaker claimed, the main roads would be practically mudless and smooth. Their crust would be waterproof owing to the plastie binding used, and stones could be picked out of their matrix. Experience, the speaker stated, showed that such roads would last twice as long as a waterbound road, which had no cohesion. There was, Sir John continued, reason to believe that still better results would be obtained by using, in conjunction with such plastic binders, stones much smallei indeed than Macadam's limit. Briquettes made up with smaller stone bound with, a suitable material had proved to be ol great strength. A question now angaging attention was, the lecturer continued, that of providing an elastic skin ©» carpet to lie on top of the crust, and take the shocks of the traffic.

Laboratory experiments, he stated, gave reason to believe that this would be accomplished. A layer of bitumen placed over the'road-crust would protect the latter from injury, and could itself easily be repaired as occasion required. This' system of road construction was, he said, now about to be tested in actual service.