Spanning the Harbour

Sun (Auckland), Volume 1, Issue 118, 9 August 1927, Page 10

Spanning the Harbour

Waitemata Bridge for £690,000 “EVERYBODY rejoice, and listen to the good news. Let Ei the steam whistles blow. Let the church bells ring. “Remember what Brooklyn Bridge did for Brooklyn. “Remember what Allegheny Bridge did for Allegheny. “Remember what Camden Bridge did for Camden." Thus an American paper hails a new bridge to suburban territory opposite San Diego, California. It might be added: Look what a Waitemata bridge would do for North Shore.

CUGGESTIONS that a bridge across the Waitemata would be too costly to warrant its construction are scouted by competent engineers and bridgebuilders. They deride comparisons with the Sydney Harbour bridge and the Forth bridge, fabulously expensive structures, and point out that the type of bridge wanted for the Waitemata does not resemble the giant structure planned for Sydney, where an immense and lofty central span is necessary, with deep water, and costly property for the approaches, factors in raising the total cost to the £4,000,000 mark. BUILT ON CYLINDERS Engineers agree that the Waitemata could practically be bridged by a relatively low structure flung across the harbour on cylinders sunk into its bed. From Jellicoe Street, Freeman’s

Bay, to Northcote, is one line that the suggested bridge should follow. Another provisional plan sets the North Shore end of the structure In the middle of Shoal Bay, whence causeways could radiate from the terminal to Northcote, Takapuna, and Bayawater. For the present the scheme Is in so nebulous a stage that little attentio*.

, need be devoted to considerations of j the exact line that should be fol- | lowed. The main point is whether the project is practicable. As to that, it lis agreed that the bridge would not j be more than 5.000 feet long between approaches, and that no insurmountable engineering difficulties are in the way. ENGINEERS INTERESTED Engineers who have interested themselves in the possibilities of the proposition have done so only to prove that it is feasible. No local body has yet lent the weight of its official authority to the proposal, but the City Council and the North Shore boroughs are all closely concerned. Messrs. Jones, Adams, engineers, of Auckland, developed one plan that has been widely discussed. It provides for a bridge 5,000 feet long, from Jellicoe Street to Northcote. Between parapets the width is 50 feet, and there are one span of 400 feet, nine of 250 feet, and nine of 150 feet, with 1.000 feet of reinforced concrete approaches. The central span would be lofty, to allow the passage of shipping, and would be built across heavy sets of caissons, each 200 feet in total length. Except for the caissons, there is a smaller parallel to the proposed bridge at Wanganui, where the suburb of Wanganui East owes its existence to the Dublin Street bridge, a line structure completed in 1914. After preliminary difficulty with piles, it was built on cylinders six feet in diameter, each sunk 30 feet into the riverbed. A BRIDGE-BUILDER’S BELIEF Plans for the Waitemata Bridge provide for the employment of similar methods. No specific borings of the harrbour bottom have yet been taken, but it is considered certain that the sandstone evident at Northcote and Ponsonby extends right across. In this material ten-foot cylinders would be sunk without trouble, particularly as the floods and floating timber of the Wanganui River would not be repeated. Mr. R. Sanders, of Auckland, was the builder of the Wanganui Bridge, and he is firmly of the opinion that a similar type of bridge could be built at Auckland. “It is absurd.” he said, “to suggest that such a bridge would run into millions. I would guarantee that It could be built for £700,000. At that figure I would build it myself.” In support of his estimates he produced a provisional schedule of quantities and prices for the Auckland bridge. Allowing the generous sum of £30,000 for contingencies, he reckoned that the outside cost of the Waitemata bridge would be £690.830 —at which figure the bridge is definitely brought within the limits of practical possibility.