27 April 2011

Humber Bridge

The reinforced concrete towers of the Humber Bridge, 533 feet tall, and its massive concrete anchorages, are founded, 100 feet below ground level, in clay. The bridge is of the suspension type, built between 1973 and 1981, with aerial-spun catenary cables, inclined hanger cables, and a continuously-welded, closed box road deck.

It is a truly magnificent piece of engineering. The statistics are incredible: 15,000 wires in each cable; 44,000 miles of wire all told; 30,000 tons of steel; 530,000 tons of concrete; a central span of 0.9 miles; another half mile of side spans. The cables alone weigh 11,000 tons, the road deck weighs 17,000 tons, and there's often a live load of 6,000 tons.

But it's only a round walk of its east and west foot and cycle paths, cantilevered out from the road deck, and positioned below this, that provides a real appreciation of its size, as the return journey takes an hour-and-a-half. The bridge's streamlined shape makes it very stable, far more so than the Golden Gate or the Severn bridges.

The south side of the Humber used to be home to numerous brick and tile works, to a cement works, and to ACC Chemicals, and was thus heavily polluted. 86 acres have been reclaimed and now form a country park. The visitor centre for this, designed by Gerard Bareham, stands just west of the bridge.

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