iron trusses to strengthen the final structures, but they were anchored on the cast iron girders themselves, and so deformed with any strain on the bridge. Stephenson maintained that the locomotive derailed whilst crossing the bridge, and the impact force against the girder caused it to fracture. However, eyewitnesses said that they saw the girder break first, and that the locomotive and tender were still on the track at the far side of the bridge. Indeed, the driver raced on to the next station to warn of the accident and prevent any traffic using the line. He then came back on the other side and drove to Chester where he gave a similar warning. Royal Commission A subsequent Royal Commission (which reported in 1849) condemned the design and the use of trussed cast iron in railway bridges, but there were other failures of cast-iron railway underbridges in subsequent years, such as the Wootton bridge collapse and the Bull bridge accident. Similar failures occurred in the Staplehurst rail crash, the Inverythan crash and the Norwood Junction crash. All the structures used untrussed cast iron girders, and generally failed due to blowholes or other casting defects within the bulk material, which were often completely hidden from external view. The Norwood accident in 1891 led to a review of all similar structures by Sir John Fowler, who recommended their replacement. Cast iron had been used very successfully in the Crystal Palace of 1851 and the Crumlin Viaduct in South Wales (built in 1857), but the first Tay Rail Bridge of 1878 failed catastrophically due to its poor use of the material, putting the cast iron lugs on the columns into tension. The Tay Bridge disaster stimulated engineers to use steel, as exemplified by the Forth Bridge of 1890. The Dee bridge was later rebuilt using wrought iron, after several more failed attempts to use cast iron by Stephenson. See also List of bridge disasters List of structural failures and collapses Structural engineering Structural failure References External links Aesthetics versus function: The fall of the Dee bridge, 1847 Contemporary account of accident Examination of Tay and Dee bridge disasters Bridge disasters in the United Kingdom Bridge disasters caused by engineering error Railway accidents and incidents in Cheshire Railway accidents in 1847 1847 in England History of Chester Disasters in Cheshire Bridges across the River Dee, Wales 19th century in Cheshire May 1847 events 1847