05 March 2014

Tyneside Bridges: 1. Ouseburn Viaduct

I'm continuing my series of posts on the bridges of north-east England which I visited as part of an IABSE study tour last year. The second day of the tour had begun with a visit to the delightful Cragside Iron Bridge. From there we went to Newcastle-upon-Tyne.

Three tall bridges span the Ouseburn Valley in Newcastle-upon-Tyne. The Ouseburn Viaduct was the first of the trio to be built, in 1839, to a design by John and Benjamin Green. To place it in context, it was built ten years before Stephenson's High Level Bridge in the same city, and was completed in the same year as Brunel's Maidenhead Bridge for the Great Western Railway. At this time, anything other than a brick or masonry bridge remained relatively unusual on the railway.

Brunel's famous timber railway viaducts in Cornwall would not be completed for another two decades, but timber structures were springing up in various other places. In the same year as the Ouseburn Viaduct, the timber Scotswood Bridge was completed in Newcastle. Within the next decade, timber arch viaducts would be completed at Etherow and Dinting Vale, both near Manchester.

The Ouseburn Viaduct, along with the Willington Viaduct built at the same time on the same railway line, was originally a timber arch structure, built using the Wiebeking system. This involved the use of laminated timber sections, made from Baltic softwood, and preserved by Kyanising.

The timber bridge lasted for three decades, and was replaced in 1869 by the wrought iron bridge which remains there today. The pattern of the ironwork closely followed the geometry of the original timber structure.

In 1885, the bridge was widened, doubling the number of arch ribs, to carry additional railway tracks. Since then much of the valley floor has been infilled, hiding the original stone piers, which appear to have been much taller in old images and drawings of the bridge.

This wasn't an easy bridge to photograph, half hidden by trees and by adjacent structures.

There's a lovely quote in Benjamin Green's ICE paper concerning this bridge, from another consulting engineer:
"It appeared to me that to cross the Ouse Burn and Willington valleys, would be a work of so much labour and cost, that I would not conscientiously recommend the Committee to prosecute their plan. These difficulties, however, are likely to be removed, and most effectually surmounted by the great scientific and practical knowledge of Mr Green, who proposes to pass over them by bridges of peculiar construction, and at a comparatively light expense. To him I would most willingly transfer that responsibility, having no pretensions to skill in bridge building myself."
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