The Tay Bridge was designed by Thomas Bouch. To allow shipping to pass up the Tay to Perth, a clearance of about 88 feet was required between the bridge girders and the high water mark in the middle of the firth. On the south bank, at Wormit, the land rose steeply to a height of about 200 feet, and this proved ideal as a jumping-off point for the bridge.
After leaving the bank on a short curve, the track climbed gradually at 1 in 490 until it reached pier 29. It then ran level to pier 36. After passing pier 37 the track fell rapidly at 1 in 74, until it reached the north bank at Dundee. At pier 53, the track entered a large, sweeping curve that took it alongside the bank and down to a height of about 40 feet above high water.
The overall length of the bridge from bank to bank was over 2 miles, which at the time made it by far the longest bridge in the world.
This section includes two interactive diagrams showing Bouch's bridge design in detail. It may be useful to refer back to these when analysing the evidence for the disaster.You need the Flash Player (version 4 or higher) to view this - download Flash. http://podcast.open.ac.uk/open2media/forensic_engineering/flash_work/design_rollovers/bridge_rollover.swf
Front and side elevations of bridge pierYou need the Flash Player (version 4 or higher) to view this - download Flash. http://media.open2.net/forensic_engineering/flash_work/design_rollovers/column_rollover.swf
Column section close-up