Collapse of the Tay Bridge--- the Cause?

Question

As best I know, the cause of the collapse of the Tay Bridge has intrigued engineers over the years.A "mystery" that engenders people to find the "solution"!!

Are there any theories, recent and otherwise, that can conclusively prove the cause.?

Answer 1

http://www.mcgonagall-online.org.uk/poem...

Insufficient allowance for wind.

Answer 2

As far as I am concerned, there is no 'mystery' to the Tay Bridge disaster. The Bridge was poorly built, and claculations did not take into account the wind forces that could be exerted on it, particularly on the 'high girders' section, which is the part that actually collapsed. Read 'The High Girders, The Tay Bridge Disaster' by John Prebble. To quot from the Wikipedia entry in respect of the Court of Enquiry:-

'The official inquiry was chaired by Henry Cadogan Rothery, Commissioner of Wrecks, supported by Colonel Yolland (Inspector of Railways) and civil engineer William Henry Barlow. They concluded that the bridge was "badly designed, badly built and badly maintained, and that its downfall was due to inherent defects in the structure, which must sooner or later have brought it down".[2]

There was clear evidence that the central structure had been deteriorating for many months before the final accident. The maintenance inspector, Henry Noble, had heard the joints of the wrought-iron tie-bars "chattering" a few months after the bridge opened in June 1878, a sound indicating that the joints had loosened. This made many of the tie-bars useless for bracing the cast-iron piers. Noble did not attempt to re-tighten the joints, but hammered shims of iron between them in an attempt to stop the rattling.[3]

The problem continued up till the collapse of the High Girders. It indicated that the centre section was unstable to lateral movement, movement that had been observed by painters working on the bridge in the summer of 1879. Passengers on north-bound trains complained about the strange motion of the carriages, but they were ignored by the bridge's owners, the North British Railway. Some distinguished passengers, such as the Provost of Dundee, had timed trains moving across the bridge and found they were travelling at about 40 mph, well in excess of the official limit of 25 mph.'

It must be said that the engineer, Thomas Bouch, who had desigend the bridge had earlier built others in a similiar form including Deepdale Viaduct on the Stainmore line, which stood with out problems unti the lines closure, and the abutments of which can be seen from the windows of the room where I type this.