ABSTRACT
When the Severn Bridge opened to traffic 50 years ago, it was a world-leading design with a very economic design for the 3240 ft. main span. In 2005 an internal cable inspection was carried out which revealed unexpectedly poor results in terms of corrosion, broken wires and strength loss. This prompted the implementation of a series of measures, starting with acoustic monitoring and followed by a cable dehumidification system. Both these systems continue to operate today, preserving the cables and providing ongoing data on their condition. Two further internal cable inspections in 2010 and 2016 have revealed that the deterioration has now slowed to a minimal rate.
This paper describes investigation and rehabilitation work carried out since 2005. It includes some special investigations into low stress/high cycle fatigue testing of cracked wires and friction tests to refine the evaluation of broken wire redevelopment length. It seeks to provide lessons learned and guidance for suspension bridge owners on how to deal with similarly deteriorated cables.
