Building bridges during major A1 upgrade, with our propping expertise

The challenge

The bridge formed part of a major highway infrastructure upgrade designed to increase network capacity and support growing traffic demand. The scheme included carriageway improvements and the replacement of an existing bridge crossing over a key rail corridor.

The new bridge structure consisted of 16 central girders installed as braced pairs, comprising more than 3,000 tonnes of structural steel and decking. Understandably, the assembly and installation of the bridge presented project teams with a considerable logistical challenge, requiring a bespoke series of temporary works.

Ben Adcock, Lead Temporary Works Co-ordinator at Costain, principal contractor on the project, said:

“Due to the poor ground conditions experienced on site, the geotechnical team anticipated significant movement could occur at the back-span embankments and abutments during construction. As a result, we were unable to land the new bridge deck directly onto the new abutments, as the bridge bearings would not have been able to accommodate the anticipated movement and loads.

“Temporary works therefore proved critical to maintaining the programme. We needed a temporary propping and trestle scheme that would provide additional support to the back-span beams of the bridge deck during the initial installation phase, before loads could be gradually transferred to the permanent abutments.”