An assessment of the capacity of the original bridge carried out by Network Rail determined that it was in poor condition, and that is was not capable of carrying the required loading under current standards.
As significant and potentially costly repairs would have been required to retain the existing structure, it was decided that the best value option would be to reconstruct the footbridge.
The new footbridge, designed to accommodate pedestrians and cycles, utilised the existing abutments which were assessed as being capable of supporting the new structure. The shallower construction depth of the new bridge allowed a 603mm increase in headroom at the lowest point between the soffit and rails below.
The main challenge presented by the site was the extremely poor access to the structure for materials and large construction plant. This was partly overcome by delivering the main span of the new structure to the site by rail. The new bridge was loaded onto rail wagons from a nearby factory yard and transported to the site location to be lifted into place by a pair of rail mounted cranes, completing a tandem lift.
- Removal of fill material from the bridge deck to reduce the lift weight during removal and to expose the deck plates.
- Dismantle and removal of existing bridge deck plates in sections.
- Removal of the existing bridge main girders, and removal off site.
- Preparation of the existing abutments, and installation of the new pre-cast cill units.
- Installation of the new bridge by tandem lift using two rail mounted cranes.
- Re-construction of the earthwork approaches to the bridge.
- Installation of drainage and downpipes from the structure.