The bridge reconstruction was to be integrated into the North Lincolnshire Re-signalling Blockade. The fact that the works had to be carried out over Christmas meant that a significant amount of planning and risk evaluation was required. By utilising this opportunity, CML was able to optimise the planned access, removing the need for future disruptive possessions and therefore reducing the impact on train operators and customers alike.
All fill material on the arch was removed to a designed sequence, and the arch was demolished in a designed sequence as well. Due to the nature of the arch, the demolition lowered the abutment to the arch springing level which was some 1.57m below the level required for placing the cill units of the new bridge.
The novel solution chosen involved the use of pre cast cellular ‘riser units’ which were placed on a screed and then filled with concrete to generate the required mass and strength required in the design. The cellular units were placed by a hi-ab lorry, and concrete was supplied from a nearby batching plant opened specifically for these works.
After the riser units were completed, the bridge was driven into position by SPMT and then pre-cast ballast retention units were placed before backfilling commenced. The bridge was handed back on 27th December at 21.30, 48 hours before the end of the blockade possession.