From the Kearney Files.
In a week or two the arch of the Harbour Bridge will be locked, and Sydney will have one of the chief wonders of the world, the largest single span yet built, 1650 feet, or 672 feet 6 inches longer than the Hell Gate arch of the New York Bridge. Some of the details of this engineering feat are most interesting. The weight, of the steelwork of the bridge is set down at 50,300 tons, all neatly all neatly weighed out and booked up. Of this 25,300 tons is British Steel and other from the Broken Hill Proprietary's steel works at Newcastle. To produce this steel required 38,000 tons of iron ore, 7,000 tons of limestone, 1,800 tons of dolomite, 90,000 tons of coal, and 10,000,000 tons fire and silica bricks to line the furnaces. The weight of the centre of the bridge is 24.4 tons per square foot. This weight increases to 66.2 tons at the abutments. The highest part of the arch is 445 feet above the water level. The Bridge dominates the city and is visible from points on the Blue Mountains. The headway between the decking and high water is 172 feet. The Bridge provides a main roadway of 57 feet between kerbs, with two lines of railway on either side of the road, and two footways 10 feet wide. The capacity of the bridge is 160 trains, 6,00 vehicles and 40,000 foot passengers per hour. The deflection with this load will be just 4 1/2 inches. But some idea of its carrying capacity can be gathered from the fact that the two creeping cranes used in the erection of the panels, which have crept from either side right to the top of the arch, weigh 560 tons each, and they lift up to 160 tons. The timber required for the transoms and planking totals 1,000,000 grey gum and iron bark. The approximate weight of everything, steel, stone, sand, cement, is 310,300 tons. The fabrication of the bridge has taken place in the largest workshops in world, 1,080 feet long, right alongside the abutment of the northern side of the arch. The contract price of the bridge was £4,217,721 11/10, but it will cost considerably more as the Government agreed to stand by any extra wages demanded and received by the workers.
Elfric arrives.
A remarkable coincidence has brought Elfric Wells Chalmers Kearney, the inventor of the Kearney High Speed Railway to Sydney at the time the harbour bridge arch is about to meet. Mr. Kearney's visit is in connection with a proposed railway line from Manly to Newport. There are other private firms willing to build the railway and to run it on terms, but Mr. Kearney plans appear to be first favourite as far as the public, for whose convenience the line is to be built, is concerned. But the point about his visit is the reminder that a few years ago that a few years ago he put in a price for tunneling the harbour to carry a tube railway. At that time the engineering mind was considering whether to carry the traffic under or over the Harbour on a bridge. The bridge won. Although the contract for the bridge is nearly £5,000,000,whilst one of Mr. Kearney's tunnels for railway purposes could have been constructed for £700,000. It is intended to put two tunnels under the harbour for a start. One of the influences against the tunnels was the fact that about that time the harbour was already being tunneled to carry electric power cables, and a fault in the harbour bed let in the water to such an extent that the project was held up. But a young man who had been working on the job had a brain wave . He waved it before the Works Department . All he asked for was the loan of a punt and some pipes and a supply of cement. The fault was located and the punt anchored over the spot. From this point cement was allowed to percolate into the fault until it gradually filled up and hardened, and the leak in the tunnel was sealed. After that the rest of the work was easy. These faults are common in sandstone which is the natural base of Sydney. Although we have the bridge the tubes may yet be put under the harbour to give access to other parts of the North Shore . But the fact they have soon been forgotten shows what a short memory the public have.
The Age (Melbourne) Tuesday 29th July 1930.
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