Chester in Northwest England had been an important settlement since Roman times but its status as a regional center received a major boost when a new long-distance railway line opened in the 1840s, running between London and Holyhead on the island of Anglesey. The line passed through Chester and had to cross the River Dee just outside the city at a point where the river is still tidal.
One of the principal engineers for the line, Robert Stephenson, designed a bridge for the crossing. He was the son of George, of Rocket fame, who was often called the ‘father’ of the railways. Although a span of some 80 m (250 ft) was called for, Stephenson’s bridge had just two stone piers because of concerns about the foundations; these were linked by a construction of cast-iron girders on which oak joists were laid that supported the twin tracks.
The bridge opened with great ceremony in November 1846, but just six months later, in May 1847, a local passenger train was passing over the bridge when it suddenly collapsed. The driver had nearly completed the crossing when he felt the final span start to give way beneath the steam engine. He managed to get the locomotive onto firm ground on the far bank, but the tender and train behind him fell 10 m (30 ft.) into the river below. The subsequent investigation revealed that a cast-iron beam on the bridge had fractured at its center. Although it was not understood as such in those days, it is now generally accepted that metal fatigue was the cause. After the accident the widespread use of cast iron in bridge construction ceased on account of its brittle nature.
When did the Dee Bridge Collapse: May 24 1847
Where was the Dee Bridge Collapse: River Dee, Chester, UK
What was the Dee Bridge Collapse death toll: Of the 20 or so passengers on the train, five were killed and many others injured.
You should know: Following the accident Robert Stephenson used only the tougher material of wrought iron in his future railway bridges, such as those at Conway and across the Menai Straits.