Broughton Suspension Bridge - Cause

Cause

An investigation found that a bolt in one of the stay-chains had snapped at the point where it was attached to the masonry of the ground anchor. There was criticism of the construction method used, as the attachment to the ground anchor relied on one bolt rather than two, and the bolt was found to have been badly forged. A number of other bolts were also bent but had not broken. It emerged that three years previously the distinguished Manchester engineer, Eaton Hodgkinson, had expressed some doubt about the strength of the stay-chains compared with the suspension chains. He had said that they should be rigorously tested, but they were not. It also came to light that some time before the accident one of the cross bolts had started to bend and crack, although it was believed to have been replaced by the time of the accident. The conclusion was that, although the vibration caused by the marching had precipitated the bolt's failure, it would have happened anyway.