The BBC report that £2.4m of funding has been agreed to repair Victoria Bridge in Bath, which I believe is the earliest of James Dredge's unusual suspension bridges to still be standing (picture copyright Pierre Terre). The bridge, which is Listed Grade II* due to its historic importance, was temporarily closed in 2010 following the discovery of cracks in some of the main metal members.
Works are expected to take place over 12 months starting in April 2013. Bath's report on the choice of refurbishment option makes interesting reading - the preferred solution is to take down most of the original wrought iron and replace it with a steel replica. While this isn't great in terms of retention of historic fabric, it is probably a sensible conclusion.
I am advising on this bridge and it is a most interesting project. There are two main structural issues. First, the capacity of the deck is around 1.5Kn/m2 similar to the bridge of Oich by Dredge,and perhaps OK in the Highlands but this bridge is soon to be in a new City quarter with houses, a football ground and an event space. The second is around the repair of the wrought iron. The cracking which was happening on a weekly basis was fatigue, and the issue is that even if you can repair the cracks how can you be sure it won't crack somewhere else.
ReplyDeleteThe issue of monitoring and extending the life of older bridges is going to be subject of a large research programme by a group of Universities including Bristol. Clifton will be one of the case studies.
Finally Bath Council provided me with fees for an historic desk study of Victoria Bridge which has revealed a huge amount of new material about Dredge, and following various consents should be available as a public document later this year. Some of the failures are well documented. One nice one is that when the Clifton Bridge Company decided it couldn't afford Brunel's design, Dredge offered his patent as an alternative. Brunel was asked to comment on it, but he said he was too busy.
Alf Perry. Bristol