In the early eighteenth century, the Severn Gorge’s growing industries in Coalbrookdale and Broseley needed a more reliable crossing. The only way to cross the gorge was by ferry, so Abraham Darby III was commissioned to build a bridge. The iron for the new bridge was cast at his foundry, and shares were issued to raise the required funds of £3,200, Darby agreed to fund any excess. The construction had no precedent, and so, the method chosen to create the structure was based on carpentry, where each member of the frame was cast separately using different properties of cast iron. The finished structure needed to span 100 feet rising to 60 feet above the river, with the largest parts being the half-ribs, each about 70 ft long and weighing 5.25 tons. More than 800 castings of 12 basic types were used in the construction of the bridge. The cost of the project was far more expensive than first envisaged, with Darby bearing most of the cost overrun, and was in debt for the rest of his life. The bridge was raised in the summer of 1779 and opened on New Year’s Day 1781.
Posted by maisonburke on 2012-11-28 10:23:49