MAIN HIGHWAYS

New Zealand Times, Volume LII, Issue 12250, 23 September 1925, Page 2

MAIN HIGHWAYS

A NOTE OF WARNING THE QUESTION OF ECONOMIC SOUNDNESS ADVICE BY MAIN HIGHWAYS BOARD It is doubtful if there is any matter which occasions so much concern, to local bodies in New Zealand at the present time as does that of providing roads of a standard sufficient to stand up to modern traffic conditions. So heavy has the cost of maintenance become under the old system of water-bound macadam, that all over the country county councils are anxious to try any system which promises to giv© relief. The institution of the Main Highways Board which subsidises tho efforts of local bodies in this direction is a practical recognition by the Government of the necessity for such improvement. A real difficulty has been found, however, that many local bodies, in their anxiety to provide permanence, are submitting to the Highways Board plans of proposed expenditure which exceed tho mark of economic soundness. It is obvious that no plan of road improvement is sound which will entail on the public a charge greater than the saving effected by the change, and as an indication of what does constitute a payable proposition in this direction the Main Highways Board has issued the following circular to local bodies. The necessity for this will be readily 6een when it is understood that some of the plans submitted have been based on a capital expenditure per mile of as high as <BII,OOO. * A WORKING BASIS The circular proceeds as follows? Road improvements may be divided 1 broadly into two classes; (1) Improvement in grade and alignment; (2) improvement in the running surface. This investigation will be limited to an improvement of the second type. Let us assume the following facts: A water-bound macadam road in poor condition, 5 miles in length, is costing at the present time <2150 per mile per annum. The averagefedaily traffic throughout the year is 100 motor-cars, 30 motor lorries, and 12 motor cycles. It is desired to ascertain tho maximum capital expenditure that is warranted in improving the road to a astisfactory standard. If the average motor-car is transferred from a water-bound macadam road in poor condition to a good bituminised surface the maximum saving in operating costs that can be expected, is id per mile. In case of the average motor track the maximum saving would probably be about 3d per mile. In the United States of America the estimated figures are much lower per mile than the above, but the cost of running motor vehicles in this country is much greater than in the U.S.A., ana the savings are therefore proportionately greater. A motor cycle may be assumed as saving id per mile. The maximum possible savings per mile per. day on,the road under when improved with some form’of well constructed bituminous surfacing will be as follows: 109 cars at sd, 75d; 30 lorries at 3d, 90d; 12 motor cycles at Jd, 3d; total, 168d—* 14s per day, or <8255 10b per annum. NATURAL TRAFFIC INCREASE In the United States, in the absence of extreme conditions, the assumption usually made is that the traffic will be doubled in five years, and this assumption is a fair one to make in New Zealand. Therefore, in the next ten years, by improving the road surface, the possible average annual saving through traffic economies will be double the present day saving, that is, <Bsll per mile per annum. The present cost of maintenance is <BISO per mile. If an attempt were made to maintain the existing road under the increased traffic, it is quite likely that the maintenance would increase to <B3OO per mile in 5 years' time. The maintenance on the new form of pavement' in fivo years' time will be, say, <BI2O per mile, so that it is fair to assume that the improved pavement will mean a saving in maintenance expenditure of <6IBO per mile per annum. The total possible savings will therefore be <£69l per mile per annum. Owing to the fact that estimates of the cost of construction work are very often exceeded, and owing to other doubtful factors it is most desirable that this estimate of possible savings be a conservative one. The annual overhead charges on the capital expenditure should therefore not exceed twothirds of the anticipated savings. Twothirds of <8691 is ,£460 13s 4d. MAXIMUM EXPENDITURE The amount of the loan which could be redeemed in 10 years at 6 per cent., with an annuity of <8460 13s 4d, is approximately <83400. This sum represents the maximum capital expenditure per mile that is warranted in surface improvements on the road in question under the traffic intensity specified. It will he observed under assumptions that for the first five years the community will really be losing money on the proposition, as the traffic will not have increased sufficiently to bring the savings in operating costs up to the estimated average amount. If .an immediate return is required on the capital expenditure. the cost of the improvements would have to ho limited to one-half of the above figure, i.e., JJITOO* per milo per annum. Any proposition which would provide a good running surface at an expenditure of any amount *rom .81700 to <83400 per mile would he economically sound.