GREAT SOUTH ROAD.

New Zealand Herald, Volume LXII, Issue 19061, 4 July 1925, Page 13

GREAT SOUTH ROAD.

THE PAPAKURA DECISION. HIGHWAYS BOARD'S VIEWS. BITUMEN PAVING SUPPORTED. ESTIMATED COST, 15000 A MILE. The powers of the Main Highways Board in relation to the maintenance of through traffic roads is set out in a letter written by Mr. M.; H. Wynyard, a member of the board, to the Great South Road Improvement Association. Tho letter was prompted by the controversy regarding concrete and bitumen, the Papakura Town Board having declined to proceed with tho paving of its section of the Great South Road in bitumen as favoured by the Highways Board, insisting that it would have concrete or nothing. The association wrote to Mr. Wynyard, enclosing a copy of a letter by Mr. M. Rocke, of Devonport,' published in the Herald of June 30, and asking what action the Highways Board would take in the event of a town board or district deciding to "sit tight" and do nothing to tho South Road. Dealing first of all with Mr. Rocke's reference to the failure of bitumen surfaces, Mr. Wynyard said that Auckland had been unfortunate in the class, of bitumen surfaced roads which had been laid down. But it was a fact, conclusively, proved beyond all question of doubt, that properly constructed roads with bitumen surfaces, were equal to carry traffic many times greater than that on the Great South Road, south of the manufacturing centres terminating at Otahuhu, and in climates much warmer than the Auckland Province. ' - V

The Cause of Failures. Without dealing with the individual roads, it could ba stated generally, that the failures in this district were due to want of adequate foundation, drainage, and consolidation, before putting on the bitumen top and lack of attention afterwards. Jhe conditions laid down by the engineer of the Main Highways Board for the Great South Road, provided adequately for these essentials. "I can understand the people who have experience only of the bitumen road failures in this district preferring concrete,"'said Mr. Wynyard, "but the Highways Board has opportunity of a wider investigation. The cost of ; the work on the Great South Road is largely attributable to the fact that the alteration of the grades are provided fori and want of proper maintenance has left but little depth of metal available in situ. Had the position been otherwise, the cost of a completed bituminous concrete r,oad would practically have been halved. As it is the completed bitumen 'hot mix' road will probably run to about £BOOO a mile of which the board is''prepared to find half. . "In deference to the, present preference of some localities for concrete the board has intimated it will agree to any local body so desi-ing laying down its section in concrete, and to subsidise such section to half the cost of a bituminous concrete road On the above figures it would be providing 'the same ( contribution, £4OOO a mile, that it is giving on the Auckland-Henderson road, therefore it can hardly be successfully argued that the the board is giving the latter road preference over the Great South Road beyond Otahuhu. It is also an instructive point that the One Tree Hill Road Board, which had the opportunity of adopting a cement concrete road, has f> after making full investigation, decided in favour of a bituminous concrete road, hot mix; using Trinidad natural bitumen. "The engineer to our board states em-, phatically that the standard of foundation he has specified is ample for the

louth Road. . , season's traffic on tasjroad to '6v.' Hho ths surface coat; with' proper mnintct£ ante meantime,. The Mamirewa section* quoted by Mr. Rocke,, as a Jypioai bitumen failure, suffered Worn all the uefects I have mentioned above;,.and was doomed from the start, but -except where t/ia total, polUpsd o! th<) i rfotmd&tipnji haa ;resuited^ih disintegration of; the surf,'ice, it indicates that, had the* bitumen ijurfa3e had solidity to support, it, it wciuld have lieen smooth.and unbroken, [•-. "Mr. Tyndall, the board's engineer, and other engineers of experience, staio that giveh the foundation and- consolation prescribed, a sealing coat over the metal surface at a cost of about £BOO a mile, and with proper attention at a yearly cost of, say, £l2O ii tnile, would ' 1 give a good .surface for present and considerable prospective traffic. . i When the-;' v increase of traffic warranted it- a good penetration course of 'hot-mix suvfa-.:o could be applied. This provides f.;ir pro-' gressivo construction as traffic* increases, . y and with such construction and propter attention the road, is an improving, and not a wasttng asset. "I have naturally given a good deal of attention to the question of this road, and." it appear* to we that if this progressive system of construction is adopted, a large ' proportion of the estimated cost of a bituminous concrete, or cement concrete road would be meantime saved, while a read suited -to thp requirements of traffic would be provided. I am glad of - the opportunity your letter has afforded me of making this statement, which I may say is the opinion of; the board, and .which I hope may be of use in the consideration of the improvement of> this important highway, now in such a doplorable condition. . Enforcement of Maintenance. , "I may remark, referring to your other quest lon, that the Highways Board has been . anxious to meet, as, far as it can, the wishes of the local authorities on matters of construction, and has placed its engineer in , direct touch with the corporations concerned witb this, object in view., .All this ha.B, been with a View to an early agreement as to reconstruction, of the road, which I hope will result. ' f "Should, however, any of the bodies decide not to proceed with construction, the-board then undoubtedly will require the rOad to be maintained in an adequate condition for the traffic using it.; The board finds one-thirJ of tho cost of maintenance, and it hopes to have shortly statutory authority to increase it to 50 per cent., and it is obviously its duty to see that-its ifunds, mainly from motor vehicles, are applied to ensure such traffio • a properly maintained road to run on. While the board has no mandatory power as regards construction, it has 'with regard to maintenance, and can assume the work of maintenance itself and recover the statutory proportion from the local body.? "Regarding the construction of the road from the local ratepayers' standpoint, I would like to make these remarks:—By adopting the progressive system outlined - above. considerable present cost will be saved. The proportion of heavy , traffic license fees uader the scale for use of this road should be considerable and' increasing with the traffic, and as it all goes to the local "bodies it should ease the amount of interest, sinking fund and maintenance payable by them considerably. Benefits of Construction. 'There is one motor veSicle t9 every 14 persons in New Zealand, the highest proportion in the world outside the United States. With a good road the Jvj country to Papakura .will, with the rapid growth of Auckland, - become , suburban in its character, with such motor-using public, and values will r rapidly rise. From a farmer's stand- 1 r, point the access to markets and cartage to and from the city will be lightened and time, which is money, will be saved as well. Add .ty tKeise tW fact that onehalf of the burden ' of construction is taken off their'-shoulders and ontj-third— I hope shortly one-half-—that of maintenance, . .. . "These considerations are strong arguments in favour of piopn- construction, "at' least of- the progressive nature suggested, and while discharging the local bodies' undoubted obligation for proper road provision will, I feci acre, bo -to the msiterial advantage of tlie ratepayers themselves." In a further note Mr. \Vyhyard said:— "Assuming the cost of reconstruction of tlwi road according to board specifications apd including the sealing coat at £SOOO a mile, the local bodies' proportion will be £2500 a mile. Their share of annual interest, sinking fund , and maintenance would be about £250 a mile, and less if the board can pay half maintenance. Properly to make up and maintain the present surface * would hardly cost less, with the road still an . indifferent one, and 'the cost of reconstruction only postponed." /