Construction
Early skew arch bridges were painstakingly built from masonry blocks, each individually and expensively cut to its own unique shape, with no two edges either parallel or perpendicular. A fine example of such construction is the famous Rainhill Skew Bridge, which was designed with a skew span of 54 feet (16 m), in order to give a clear span across the railway of 30 feet (9.1 m) at a skew angle of 56° by George Stephenson and built as a full-sized wooden model in an adjacent field before being completed in 1830.
A contemporary skew bridge, built to carry the Haggerleazes branch of the Stockton and Darlington Railway over the River Gaunless in County Durham proved too difficult for the original contractors, Thomas Worth and John Batie who, after piling the foundations for the abutments and laying the lower courses of masonry, abandoned the work. The contract was re-let to James Wilson of Pontefract on 28 May 1830 for £420, an increase of £93 over the original tender. As the principles were not completely understood the work continued to prove difficult and its imminent collapse was solemnly predicted right up until the time, a few days before the opening of the branch, the centring was removed and the crown of the arch settled by less than half an inch (13 mm).
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—Edmund Burke (1729–1797)
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