Designing structures to bridge a busy rail line and connect the UK’s first eco-town to an existing community

Bicester Eco-Town Rail Underbridge and Pedestrian Underpass

How can you build a bridge across a major rail line in just 100 hours? Oxford City Council faced this problem when creating a new transport link to connect the local community with the proposed site for the United Kingdom’s first eco-town.

The council hoped to build 6,000 new zero-carbon homes but plans were stalled by the Chiltern line: a railway separating the proposed site from the nearby community in Bicester. To overcome this barrier, a new underbridge and underpass were planned and looked to our team to design them. The primary challenge was installation—the Chiltern line is a busy route, and Network Rail allocated a 100-hour possession of the line during which the bridge and underpass had to be installed before normal rail services resumed. The original design, put forward by another consultant at the planning stage, proved to be unworkable. We designed an entirely new solution that saw the structures built in the neighbouring field, allowing them to be simply lifted into place during the 100-hour possession.

The solution involved a temporary works concept where two ground bearing mass gravity abutments were hung from the ends of a 1,500ft steel superstructure, which was lifted by Self-Propelled Modular Transporters (SPMTs). The SPMTs removed the need for cranes which could have jeopardised the installation had the wind speed been too high during the allocated possession. A trial lift was also conducted to further reduce the risk of the installation failing.

The five-year scheme saw many changes in the project team, but we remained committed, and our collaboration and continuity ensured the underbridge and underpass were successfully built with maximum safety and minimum disruption.