The bridge carries the Oxford Worcester Wolverhampton railway over the A4440 Worcester Southern Bypass. It is based next to an existing post-tensioned rail underbridge and spans the new second carriageway of the Southern Bypass.
Tony Gee’s involvement began initially began with a Category 3 Independent Check for Worcestershire County Council. Following completion, the construction contract was awarded to Alun Griffiths, who subsequently approached Tony Gee to design numerous temporary works packages.
During construction of the new bridge, the fill to the rear of the south abutment was to be removed. This would result in differential earth loading on the abutments resulting in an out-of-balance force on the portal.
To mitigate this, the bridge designers had specified an excavation to the rear of the north abutment in order to reduce the imbalance. Tony Gee identified that excavation behind the northern abutment may not have been feasible as the excavation would have disturbed the gabion walls and ground anchors that support the northern wingwalls. There were also timescale and access advantages related to not having to undertake the excavation.
This led to our proposal of installing ground anchors through the north abutment to restrain it. The anchors were installed with additional capacity, so that if the existing structure moved outside of limits additional load could be introduced to the anchors. The anchors also removed the need to undertake the north excavation as they were designed for the full earth pressures acting on the abutment.