Project brief

Cambridge Water Company were approached by Network Rail as they were planning to deliver a new four-platform station adjacent to the globally significant Biomedical Campus and upgrading the associated infrastructure between Cambridge station and Shepreth branch junction. To facilitate this work some of Cambridge Water’s assets would need to be diverted. The final scheme required the diversion of a 450mm Di main and cross connections to the existing 450mm and 600mm mains. To achieve this a twin 450mm Diameter UTX (undertrack crossing) and single 600mm UTX would need to be completed by Cambridge Water.

Challenges and how we overcame them

The proposed Twin 450mm UTX was found to be in close proximity to a high-pressure gas main. With close collaboration with Cadent Gas, watching briefs were arranged to trial hole and install our pipework successfully underneath the existing gas main utilising vacuum excavation and approved temporary works designs.

The proximity to the high-pressure gas main and the railway track meant that the ground levels for the connection and insertion hole could not be reduced. To overcome this a 13m x 6m x 3m deep shaft was installed on each side of the railway to facilitate the installation of the pipework and connections to host main.

Upon excavation of trail holes for the 600mm single UTX it was found that the existing water table was very high with a running sand type material present. To successfully install the UTX and connections the area would need to be fully dewatered. A dewatering specialist was appointed to carry out surveys and complete a dewatering design including assessing and obtaining requisite permits and licences.

Outcome to Date

The 450mm twin UTX crossings have been successfully installed and connected to the newly diverted 450mm main. The 600mm singe UTX crossing is currently in design stage for a fully dewatered temporary works solution which is planned to be completed in Summer 2025.