COST OF HIGHWAYS.

New Zealand Herald, Volume LXIII, Issue 19394, 31 July 1926, Page 8

COST OF HIGHWAYS.

BITUMEN AND CONCRETE. EXPERIENCE ON HUTT ROAD. COMPARISON WITH AUCKLAND. [BY telegraph.—own correspondent. ] WELLINGTON. Friday. The experience of the Wellington City and Suburban Highways Board seems tc show that the difference between the cost of a square yard of' bitumen and concrete paving is not so great as the champions of bitumen have been wont to declare. In an address delivered in June. 1924, a month after the completion of the hot mix surface of the Hutt Road. Mr. J. Paterson, city engineer, said: "A hot mix black base and asphaltic concrete top road, 3iin. deep to standard specification, with bitumen, etc., at reasonable prices, should not cost more than £4OOO a mile, and would probably be constructed wi h a proper organisation of plant and labour for £3200." It now becomes interesting, two years later, to look at the realised costs on the bituminous surfacing since done. A few months after his address Mr. Paterson presented his estimates for the Hutt Road extension scheme, which is now in hand. Under these estimates 35 7-8 miles of road were to be surfaced at the cost of £156,000. This is equal to an average cost over the whole scheme of £4630 a mile. At this week's meeting of the City and Suburban Highways Board figures were given as to the position of the scheme at present. The figures were not as comprehensive as they might be, but they revealed that 14.45 miles still remain, unsurfaced. This apparently makes the mileage surfaced 19.42 miles. The expenditure to date is given as £131,650, plus £18,450 owing, and with an offset of £10,754 for the present book value of plant and £4640 for stocks of bitumen on hand. This gives an expenditure of £134,706 on the 19.42 mile 3 of surfacing completed, yielding an average cost for a mile of £6930. Assuming that the figure thus deduced is correct the position is as follows for one mile: —Estimated cost of 33 7-8 miles of 3£in. paving, £4630; actual cost of 19.42 miles of 3jin„ paving, £6930. The cost exceeds the estimates by £2300. The above figures may be compared with the cost of recent concrete roading at Auckland. The Auckland papers this week contain particulars of a stretch of concrete road constructed by the Mount Wellington Road Board in the environs of that city. This pavement is 2 miles 65 chains in length. The concrete pavement is 18ft. wide, and on the new cross section 9in. in depth at the sides and 6in. in the centre. The cost is given at £7433 a mile. The bituminous concrete pavements laid under the Hutt Road extension scheme vary in width from 24ft. to 18ft., and their depth of 3jin. is approximately half the average dept' of the Auckland cement concrete road. Their cost, sosfar as can be gathered from these latest official figures averages £6930 a mile, or about £SOO a mile less than Auckland.