Cardiff Intersection Bridge

Relevant RTS critical priority(ies):
Low emissions

Electrification would be cheaper and simpler if it wasn’t for all the existing structures that cross the railway. Bridges pose a significant challenge, with the need for electrical clearances a key safety and performance requirement. Raising a bridge or lowering track to achieve required clearances can be a key driver of cost and disruption.

Electrifying the Great Western Main Line into Cardiff faced a particular challenge with the Cardiff Intersection Bridge. This is a very low and highly skewed bridge near Cardiff Central Station. It carries the local railway over the Great Western Main Line, which itself crosses a substantial culvert. Bridge reconstruction was costed at £50m, track lowering and culvert diversion was estimated to cost £15m and either option would cause very significant disruption.

Network Rail worked with Andromeda Engineering, Siemens, GLS Coatings and the University of Southampton to develop an alternative design which used insulated coatings and surge arrestors to carry the overhead line under the bridge, while maintaining safety. This avoided rebuilding the bridge, lowering the track or diverting the culvert. The combined development and installation cost under £1m.