SURFACING OF ROADS

Dominion, Volume 26, Issue 49, 21 November 1932, Page 5

SURFACING OF ROADS

Cheapest Form to Use COMMITTEE’S RESEARCH A committee of county clerks, engineers and departmental officers bas been at work for the past two years attempting to evolve a system of economy in rural roadlng. Dlr. H. F. Toogood, of Wellington, convener of the committee, stated yesterday that the cheapest form of what is called hard surfacing of roads is obtained by sealing a metalled surface either with tar or bitumen. The first requirement is that a solid, wellconsolidated road crust should be provided, and it should be able to carry the heaviest loading without movement. On good foundations a crust thickness of 6in. will safely carry motor vehicles of 6J tons gross weight with four wheels; on bad foundations up to 12in. of metal or more may be required. With the road in question Mr. Toogood believes that the average thickness of crust required would not have exceeded 9in., and this by a Py°" cess of maintenance with a subsidy of £3 for £1 could have been built up while the road surface was being maintained in metal as circumstances permitted. , “The surface of the consolidated crust,” Mr. Toogood continued, “could then have been sealed with two coats at a total cost of about £750 per mile, and would' then have had a traffic capacity of at least 700 to 1000 motor vehicles per. day, including 20 per cent, of motor-lorries on pneumatic tires. There are hundreds, of miles of such roads in use to-day throughout New Zealand, and those who have, studied the question .believe that no better road is required on any main highway in New Zealand outside a radius of 15 to 20 miles of any of the four chief cities, or where the traffic is not in excess of 1000 motor vehicles per day.