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Road bridge over the uMtamvuna River - Mitchel Bridge
Port Edward district, KwaZulu-Natal


Client:Public Works Department, Natal


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31°04'32.12" S 30°11'33.94" E Alt: 1m

Extract from James Brown & Hamer's quarterly Newsletter dated January 1963:


James Brown and Hamer Ltd. have recently been awarded the R550,000 contract for the construction of a new Bridge at Umtamvuma on the South Coast of Natal, which will replace the present pont at Port Edward. The 520 ft. (158,5 m) span arch suspension bridge is to be constructed below the position of the existing pont—about 2,500 ft. (762 m) from the river mouth.

The roadway, 30 ft. (9 m) wide, excluding two walkways each 3 ft. (0,9 m) wide, will be tarmacadam on a steel deck. This deck is 675 ft. 6 in. (206 m) long, and consists of three spans.

The Umtamvuma bridge will be the first in Africa to be built of Cor-Ten steel, a high strength, low alloy material noted for its outstanding resistance to atmospheric corrosion — an important point in a bridge that is less than 1,000 yards (914,5 m) from the sea. Construction of the arch and deck embodies both welding and riveting. All welding will be carried out by James Brown and Hamer, to comply with British Standard Specification No. 2642. The welds will be tested by radiography by the South African Bureau of Standards.

To guard against corrosion, the whole structure will be shot blast-cleaned, primed and painted before leaving the workshops as well as being painted after erection.

The bridge is being built for the Public Works Department and should be completed in 1964.

Extract from James Brown & Hamer's quarterly Newsletter dated January 1965:

AS part of the National road development in South Africa, James Brown & Hamer Limited, were awarded the construction and erection of a 520' (158,5 m) span arch suspension bridge over the Umtamvuna River on the Natal and Cape Province border.

The bridge consists of approaches, concrete abutments, two concrete piers and three spans with steel road decking and supporting structure. The road contained will be 30' 0" (9 m) wide and 675' 6" (206 m) long, with a tarmacadam surface. The two outer spans are supported on the piers and abutments, and the centre span will be suspended from a steel arch 520' (158,5 m) span and 154' (47 m) above springing line.

The arch type of construction was decided on since soundings in the river bed to many hundreds of feet in depth showed no bedrock on which piers could be erected for a plate deck bridge.

The bridge is made from "Cor-ten" steel, a high-strength low-alloy material noted for its resistance to atmospheric corrosion.

The erection of the bridge is being carried out by means of an aerial cableway 775' 0" (236 m) span with towers 180' 0" (55 m) high. These towers are arranged to tip sideways by means of hand winches so that erection can be carried out at any point between the main girders which are 39' 0" (12 m) apart.

The hoist and travel motors of the cableway are electrically operated by means of push-button controls attached to long trailing cables, enabling the erection foreman controlling the work to get as near as possible to the parts being erected. This operation can be seen in the photograph [see right], where the controller on the Natal side, armed with binoculars and a transistorized loud-hailer, is directing into position a section of steel which an erection gang are fitting into place on the Cape side of the bridge.

In the two pictures [see right] showing the abutments on either side of the river, the first portion of the arch on either side is seen held in place by holdback cables from the hold-back erection structure mounted on the concrete piers, and this structure is itself tied back by steel girders to the concrete abutment.

(Submitted by Alison Chadwick via William Martinson)