ABSTRACT
In contrast to the light footbridge of Clare College considered in Paper 7554, Thomas Telford's bridge at over is a large-span masonry arch carrying heavy road traffic. The bridge has exhibited much movement and cracking since its construction 150 years ago, and is now a three-pin arch rather than a monolithic structure. The difference of total head on either side of the bridge is expressed in terms of the losses incurred by the water in its passage, and these in turn are largely due to the generation of turbulence. Telford's bridge appears to be a flat circular arch of 150 ft span and 13 ft rise, with voussoirs varying in depth from 412 ft at the keystone to 512 ft at the springings. That Telford was misled is supported by a soil survey carried out in connexion with new road works.
