The rail bridge was the product of the design team of Sir John Fowler and Benjamin Baker and the construction skills of Sir William Arrol. It cost GBP320m in today's money (about $600m) . It took seven years to build from 1883 and was hailed as a wonder of the world in its day. The technology was leading edge in that (a) it was the world's largest cantilever bridge and (b) used what was then a new material-steel.

To construct the foundation piers on the seabed, 90ft below the surface of the water, took three years, followed by a further four years to complete the structure as seen today. The workforce amounted to 5000 men, toiling from 90ft below the water to 361ft above it of which at least 63 men lost their lives. For more information refer Forthbridges

The sister road bridge is suffering from corrosion and may have to be closed to traffic, possibly within 13 years. A replacement bridge is in the planning stage but government authorties have held back authorising a new build, which will be hugely expensive project.

A Japanese team from Nippon Steel are undertaking an evaluation to determine if a system can be designed to halt the corrosion of the bridge's main cables via a process which will blast the cables with warm air to dry them out. Engineers from the U.S. are also part of the team. There is a budget of GBP12m for the dehumidification process. The bridge operator is of the view that a second road bridge will still have to be built because it could be five years before the outcome of the repair process is known, by which time it would be too late to order a replacement crossing in time for closure of the existing bridge.

For a panoramic view of the bridges see website

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posted by Nigel Cole @ 6:50 AM