CITY ROADS

Southland Times, Issue 21073, 3 May 1930, Page 5

CITY ROADS

SIX MILES DONE BY CONTRACTORS. CONCRETE NOT WARRANTED? With the cessation of road work in the city for the present season it is interesting to note that since the contractors, Isherwood, Belham and Co. Ltd., commenced operations last spring they have put down close on six miles in hot mix. This represents 77,000 square yards. Mr H. Isherwood, one of the principals of the firm, is at present in Invercargill and yesterday he gave some interesting information on roading to a reporter. He expressed himself as well satisfied with the efficiency of the local men his firm had employed and with the Council’s hot-mix plant which his firm had used in their work. The celerity with which the work had been done rtas due to the fact that the contractors .were able to give it that personal supervision which a city engineer, owing to his multifarious duties, could never give. His firm, however, owed a debt to the city engineer Tor his co-operation and assistance. Questioned as to the class of mixture his firm had used, Mr Isherwood said that his firm had used somewhat coarser materials than had previously been the case. This gave a more mosaic surface and was a far stronger job. It also made a non-skid road. The Southland stone was first class, probably the hardest in New Zealand. There was certainly nothing like it in the North Island. Mr Isherwood’s firm is one of the biggest firms of road constructors in New Zealand, and Mr Isherwood is recognized as an authority on road construction. In reply to the reporter's inquiry he stated that he did not consider concrete roads were warranted in New Zealand. In the last twelve months there had been a lot of competition with cold preparations, and it seemed highly probable that these would be largely used in future. Cold emulsions of bitumen could be put down at any time and were not dependent on area temperature. As they did away with a lot of expensive plant they were more economical than hot mix, and in other ways they effected a saving. The success of experiments in the North Island led him to believe that a great deal more would be done next season with cold preparations. For country’ highways Mr Isherwood said that he believed the three-surface road recommended by the Highways Board was most suitable. The first process consisted of putting road oil on top of the foundation surface. When this had been left for three weeks or so for settling a light coat of bitumen was applied, one inch chi|>s thrown on and the whole brushed and rolled. Finally the penetration coat was applied. This would give a highly serviceable road at a cost of only 2/6 a square yard. City streets, however, required a more expensive method of treatment.