MGF have been supporting Doocey Group (working for Cambridge Water) on the Cambridge South Station Water Main Replacement project, a key part of the wider £100 million station development designed to improve transport connections and access to the Addenbrooke’s Hospital and Biomedical Campus. As part of the major railway upgrade, the existing line was expanded from two tracks to four, leaving a strategic water main insufficiently protected beneath the new track formation. To ensure long term use, the main needed to be fully replaced and realigned before the new infrastructure could go ahead.
Three cofferdams were required to complete the works, one on the Eastern side, one on the Western side, and a third to facilitate the connection. The East and West cofferdams were installed at the same time to allow the new pipework to be threaded through culverts, which were previously installed using MGF boxes underneath the railway line. The complexity of the site, the sensitivity of the surrounding infrastructure and the importance of the water main to the wider network placed significant emphasis on the need for a safe, adaptable and well coordinated temporary works solution.
Cambridge South Station – Water Main Replacement
Doocey Group
Oliver Manning, Regional Engineer
Early engagement allowed for the Temporary Works strategy to be aligned across all parties
MGF’s involvement began early in the planning stages through multiple site visits with Doocey Group, Cambridge Water, Murphy and the dewatering subcontractor. This early engagement made it possible to create the first concept designs and ensure the temporary works strategy aligned with the needs of all parties, including Murphy’s, who reviewed all temporary works designs.
The project evolved significantly during construction, largely due to high groundwater levels, unknown underground services and several buried obstacles that only became apparent while driving sheets. These challenges, coupled with the requirements of Murphy’s required ongoing design amendments, resulting in eleven design revisions from the original concept. Throughout this process, MGF maintained a single point of contact through Regional Engineer, Oliver Manning, allowing design changes, equipment adjustments and site recommendations to be delivered quickly and consistently to Doocey.
MGF supplied a full temporary works solution that included 203 UC Tank Brace systems, 200 Series cross struts, KKD 600/8 and FKD 400/6 trench sheets, manhole bracing and all associated safety equipment including Laddersafe, Edgesafe and Davitsafe. One of the key design efficiencies came from replacing the customer’s original request for a multi frame arrangement with a propped cantilever system. With space on site extremely limited, this reduced the quantity of equipment required by utilising a sheet toe-in, also providing a safer and more spacious working area within the cofferdam. The Western cofferdam used shorter sheets to compensate for the restricted overhead clearance influenced by the nearby overhead line equipment.
MGF remained closely involved throughout the project, with regular site visits, progress checks and on the spot recommendations to support the contractors as conditions changed. Equipment was supplied on time from the Stanton depot, allowing Doocey Group to keep the project moving despite the continual challenges of site conditions.
MGF delivered a responsive and practical temporary works solution that allowed Doocey Group to install the new water main safely and efficiently within the given constraints of the environment. The propped cantilever design significantly increased the speed of installation, reduced the amount of equipment required on site and maximised working space within each cofferdam. The use of shorter sheets and a single frame level also provided clear cost and transport savings while simplifying the overall build process.
The collaborative approach between MGF, Doocey Group, Cambridge Water and Murphy’s ensured that every design update was captured quickly, resulting in a temporary works scheme that could adapt to challenging ground conditions, unknown buried features and the restricted working room surrounding the live railway. The outcome was a controlled, compliant and efficient installation that fully aligned with the demands of the wider Cambridge South Station development.
Doocey Group have captured the full journey in their case study, read here.
Trench sheets provide an effective ground solution to support the vertical faces of small to medium sized trenches and excavations. …
Our 200 series strut is a highly versatile, medium duty strut system primarily for use in conjunction with hydraulic bracing …
Designed to brace small to medium sized cofferdams as well as larger trenches, this system allows for the safe installation …
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