CONCRETE ROADS.

Manawatu Herald, Volume XLI, Issue 1979, 20 May 1919, Page 1

CONCRETE ROADS.

EXPERIENCES IN AMERICA. SUCCESS OF EXPERIMENTS. An interesting address on concrete roads was given in Auckland by the Mayor (Mr J. H. Gunson). Ills obpect was to place before the ratepayers the latest information as to the cost and construction of concrete roads. This he had obtained from Mr \Y. H. Hamer, engineer to the Auckland Harbour Board, who had recently returned from America. Mr Hamer had carried out more concrete work than anyone else in New Zealand, and in 1904 introduced the system of concrete construction of the Auckland wharves. He was, therefore, an authority on the subject, and well qualified to speak of the most mocP ern methods of concrete works in the United States. Mr Hamer found that in California, for concrete roads throughout the State, the following loans were authorised: —• 1909, £3,000,000; 1910, £3,000,000, These two loans had been practically expended, and a further lean had just been authorised of £7,009,000. There were 4,500 miles of concrete roads in the State. The general practice had been to form a 24ft. sub-grade, 15ft. wide of concrete to a thickness of 4 fins., leaving 3ft. shoulder on either side of the concrete. In many parts oiled crushed rock was topped oil: on the concreting. The cost of tins in the past had been approximately £2,200 a mile. Four to four and a-half inch - es was the thickness of concrete laid generally throughout the State of California. From San Francisco to Los Angelos, a distance of 441 miles, there was a concrete road of 4-iins. standing excellently. Tartopping was formerly used, but the concrete was standing so well that the use of the former had been discontinued.

CALIFORNIAN CAR TAX In California there was a motor (tar lax of £2 a car a year. Mr Gunson said local bodies in New Zealand had no power to levy such a. tax, but he hoped the municipal conference would adopt (he remit favouring one. Besides aiding local bodies in their road construction work, the tax would result in a boon to motorists.

Engineers in California advised Mr Plainer that the interest and maintenance of; concrete roads was less than water hound roads. The. counties spent annually £4,000,000 on maintenance of roads, Shingle concrete was found to be not successful, and had been abandoned in favour of cube chips. The cartage contracts over these roads had dropped from 20- to 0 to 12 cents a ton a mile. With the 1909 loan of £3,000,000, 2000 miles of concrete were laid 4A inches thick, at a. cost of £1240 a mile. In. one day 650 feel of concrete 15ft wide was laid by 20 men, whose wages were £1 1/- a day. The cost of this was about, £4OOO a. mile, including lillings for the valleys, Avbich had been considerable, but on Hat sections the cost bad run out at £2,200 u mile. All the concrete roads in Kedwood City, California, wore 44 inches thick. They started with 6 inches. Experiments had been so successful that they were cropping into line with other centres, and now generally adopted 41 inches. In 1910 in other centres, test speeds wore held as follows: 101. miles on concrete, 41

miles on earth, and 9.] miles on gravel, while the oil consumption on concrete was only half that on gravel. EXPERIENCE AT SEATTLE.

In Seattle, right in the heart of the city, 6 inches had been laid, with 2\ inches of sheet asphalt. The engineer of Seattle stated that ordinary concrete 6 inches thick made as nearly a perfect road as could be made, and they were now abandoning any topping on the concrete, not even asphalt or tar, as the results with the concrete had been so good. They were very particular about the grading of their sand.

New York had just appropriated a loan of £20,000,000 for roads, and a vigorous policy was being launched there in furtherance of the concrete roads agitation. In oilier parts of the States they were carrying out concrete work four inches thick at 3/- and 4/- a square yard, in many places no metal at all being used as a foundation. The concrete was simply laid on solid earth surface, after being rolled. In Seattle there wore many miles of streets laid in Sin concrete.