Presentation on theme: "Monitoring of Suspension Bridge Main Cables: The Forth Road Bridge Presented by Alastair Andrew B.Sc, C.Eng, MICE. General Manager & Bridgemaster Cambridge."— Presentation transcript:
Structural Challenges Design based on 22 ton lorries The 38 tonne lorry introduced from 1983 The 44 tonne lorry introduced from 2001 Traffic increase from 4 to 24 million Bridge presently carrying 5620 tonnes Design load 2880 tonnes
Conclusions An excellent external inspection and maintenance regime was not sufficient to prevent deterioration A good external condition doesn’t mean it is good on the inside Widely varying levels of corrosion in different areas were difficult to explain Current strength loss estimated to be 8% to 10%
Way Ahead Fitted acoustic monitoring 2006 Fit de-humidification 2007/9 Inspect and re-evaluate 2009 and 2013 Cable augmentation/replacement feasibility study.
Close up of travelling rail (turquoise) and main hanging strap that runs along this rail.
Acoustic Monitoring Commission West Cable Nov’ 08 East Cable Sept’ 09 Re-examine cables FORTH ROAD BRIDGE MAIN CABLE CRITICAL PROGRAMME Wrap cables and fit equipment Plan and construct new crossing If Dehumidification Unsuccessful Heavy Vehicles Barred 2006200720082009 2010201120122013201420152016201720182019 De-humidification Replacement/Augmentation Study Dec 2006