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Footbridge fails on all engineering counts ...

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Letters

I am sure many professional bridge engineers, like myself, will be aghast at the proliferation of 'architect-designed' footbridges.

The photograph on the front of AJ (6/13.12.01) (above) is an example of an unsatisfactory bridge. The top rail of the parapet is clearly too thin as it shows signs of buckling, and when vandals discover this, it will be bent further. A horizontal parapet rail popular with many architects today is an unsafe form of construction where children have access, as it can be used as a climbing frame. The spacing of the rails on this bridge seem to be too wide - ie more than 100mm.

Much welding has been used, which is expensive, and these are areas where paint protection breaks down quickly - especially in a marine environment. Fortunately the white finish will give early warning of this, as noted by Bill Rowe of PRP Architects (AJ 20/27.12.01).

As a bridge, this structure will require frequent inspections and be costly to maintain when compared with, for example, a simple two-beam bridge with a concrete deck and P4 type parapets (as required by the Highways Agency). I hope the owner is aware of this and is prepared to make ample financial provision.

Thomas Telford (1757-1834), commenting in about 1831 on the proposed design of a new bridge over the River Forth at Stirling, said it should have simplicity, economy and permanence. These principles are what professional bridge engineers strive to achieve in their designs every day. The Liverpool bridge fails on all counts. Have I got it wrong? It is not a footbridge but merely a piece of steel sculpture one can walk through.

Robert Fraser, Stirling

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