THE BEST ROADS

Te Aroha News, Volume XLI, Issue 6442, 26 January 1924, Page 7

THE BEST ROADS

TARANAKI’S EXPERIENCE (From “The Budget,” Taranaki.) Taranaki has the reputation—and a deserved one, too —of possessing the best roads in New Zealand. They are macadamised roads with what i£ commonly called a tar sealing, though the word “tar” is made to cover several preparations. The best streets in New Zealand cities are of macadam covered with an asphaltic cushion, Experience has taught that these roads and streets, though more costly to construct than ordinary macadam, are more satisfactory in every respect; one very great point in their favour, especially in city streets, being that they are comparatively dustless. In and around Auckland concrete appears to be held in high favour, possibly because the cement is a local production and there is abundance of good aggregate. At a conference of Auckland suburban local bodies the other day it was stated by one speaker that concrete is the only material that will stand modern motor traffic. Such a statement betrays a want of knowledge which, if acted upon, may prove costly. We have no personal knowledge of concrete roads in or around Auckland, as to whether they are standing well and giving entire satisfaction, but in Canada and the United States we have seen many miles of such roads in a state of greater or less disrepair. We might go so far as to say that the only really good concrete roads we saw during three or four months’ travel in those countries were newly laid down. Experience has proved that unless covered with an asphaltic surface concrete will crack and break up in a very few years, and it is very difficult and unsatisfactory to repair. The best road 1 construction practice in the country we have named is'to impose an asphaltic or bithulithic surface, varying from one and a half to two and a half inches in thickness, on a thoroughly sound foundation, which may be of ordinary macadam, or broken stone, ordinary concrete, or bituminous concrete. We have before us as we write a copy of a letter written by the Mayor of a city in Oregon, who writes. under date February, 1922, that in 1911 the city laid down five miles of nine-foot roadway composed of three inches of bituminous concrete and a two-inch bitulithic surface. At the same time a concrete road was laid as a continuation, of the same width and six inches in thickness. This concrete, the Mayor says in his letter, became shattered several years ago, necessitating surfacing with bitulithic, while the five mile section of bitulithic pavement has required practically no repairs, and was in excellent condition after eleven years’ service. This is not an uncommon experience, and it bears out our own observation that unsurfaced concrete roads crack up in a very few years. They should

always be surfaced with some asphalitic cushion. Even then, however, the concrete foundation is apt to disintegrate under very heavy traffic on account of its' rigidity., The perfect road is probably that constructed of bitumen concrete of varying thickness according to the traffic to be carried, with a bitulithic surface from one and a half to two and a half inches in thickness. But where good macadam exists on a sound foundation a road which is as near perfection as need be may be made at a reasonable cost by imposing a bitulithic surface on the macadam after it has been lightly scarified. The macadam road is not sacrificed by this process but is made the best use of, and its life is indefinitely prolonged, experience proving that after from ten to fifteen or more years’ service, without any, or very trifling, maintenance costs, such roads are apparently as good as when laid down. By adopting this process too there is no interruption of traffic as in the case of laying a concrete road. The practice now being followed in New Plymouth and on some of the county roads, of spraying with bitumen and spreading gravel or chips, gives good results, and if persevered with will in

a few years build up a road almost equal to those laid down with a twoinch surface in one operation. But we are convinced that where the first capital cost can be afforded the most economical method is to do it in one operation and save all future expense for maintenance or strengthening. Just a word in conclusion, about horse traffic slipping on the surfaced roads. This is partly due to the horses’ unfamiliarity with them, and to their unnecessarily high camber, perhaps also in some measure to drivers failing to keep a tight rein, but the best style of bitulithic road does not carry a glassy surface and is quite safe for horses, even on grades. We have a quantity of literature on the

subject of this system of roadmaking which we shall be pleased to pass on to local bodies contemplating road construction.