Coldstream Bridge
Carries the A698 road aross the River Tweed at Coldstream, Scottish Borders, the bridge linking England and Scotland.
Built 1763-1766.
John Smeaton was the Engineer responsible for design and construction. Robert Reid undertook preliminary design work and was the Resident Engineer for the project.
This John Smeaton's first bridge design.
There are five main arches and two small flood relief arches. To minimise costs, Smeaton made all the main arches with the same radius, so that the same wooden centring could be used for each arch. The spans of the arches vary, however, to accommodate the slight rise of the bridge (the longest span is at the middle, the adjacent spans are shorter, and the last two spans are shorter again). The centring was made for the smallest span, and was altered for the longer spans by adding a few pieces of timber at each end to support the extra courses of stone needed to extend the arches.
In 1784 a weir was constructed downstream to help prevent scour. When flow is relatively low, the weir provides the supplementary benefit of good reflections of the bridge!
Concrete reinforcement was provided for the foundations in 1922.
Major work was carried out in 1960–1961 to strengthen the deck and to widen the bridge by cantilevering the parapets.
The circular features in the spandrels are purely decorative. Curiously, the black rubble masonry infill is original, not an afterthought.[1]
See Also
Sources of Information
- ↑ 'John Smeaton FRS' edited by A W Skempton, Thomas Telford Ltd, 1981. The author, Ted Ruddock, notes that Smeaton emphasised the circles by providing a moulded section and four keystones, and also filling the area within with black rubble masonry