Day 256/365 of Steel – Birchenough Bridge

Inauguration of the Birchenough Bridge (Zimbabwe) on 20 December 1935.

Proceeding towards Birchenough Bridge from the east
Fig 1: Proceeding towards Birchenough Bridge from the east
Photo: Graph Geo

Birchenough Bridge was designed by Ralph Freeman, consulting engineer to the Beit Trust, who also designed the Sydney Harbour Bridge and the Beit Bridge over the Limpopo River. It was built with the latest high tensile steel as a single span to avoid the necessity of making piers in the river bed which was found to have shifting sands. The total weight of steel is 1,500 tons. At a length of 329 m it was the third longest single-arch suspension bridge in the world at the time.

Birchenough Bridge
Fig 2: Birchenough Bridge
Photo: Markanthonysimbi

The roadway has a width of 18 feet and footways are formed on either side of the road to allow for the uninterrupted passage of two lines of traffic. The bridge was erected by the same process as that used for the Victoria Falls Arch and subsequently for the Sydney arch—by building out the arch in two halves as cantilevers, anchored back to the rock shores by wire ropes.

Sinking of the foundations commenced in April 1934 and they were ready for steelwork in November. The arch span was completed on June 17th, 1935, and the concrete roadway was practically complete at the end of September 1935.

The entire construction took about 20 months, the contractors being Dorman Long & Company. In 1984 the bridge was widened and strengthened as part of the World Bank’s Highway Project One, but in 2000 its load capacity was reduced and only vehicle weighing less than 25 tons are allowed to cross. Unfortunately the bridge is currently in a terrible condition and god knows how much longer it will stand.

About the Author:

Bruno Dursin – Managing Director at Believe in Steel. Bruno has more than 30 years of experience in promoting steel & steel solutions. His clients benefit from his extensive network within the building industry.

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