North West Coast Connection - Morecambe Bay Tunnel
One of the most technically challenging projects of its type
22km sub-sea tunnel connecting the North West’s electricity supply
Innovative solutions with no UK precedent
One of the most technically challenging projects of its kind, the 22km sub-sea cable tunnel will house the two 400kV cable circuits that will connect the National Grid network to Moorside, a proposed 3.4GW nuclear power station near Sellafield, enabling its electricity to be exported to power the North West.
Working with sister company, Morgan Sindall Engineering Solutions (MSES), BakerHicks provided Front End Engineering Design (FEED) services on the project, including:
- Design of all aspects of tunnel and shaft design, islet and head house development, and all the associated mechanical, electrical, civil and structural works
- Design of the HV cable system and installation proposals, working collaboratively with the National Grid team
- Specialist services, including marine and environmental engineering, planning, architectural design, third party engagement and transportation management
With the tunnel posing strict ventilation requirements to ensure the cables don’t overheat when fully loaded, an islet located in the middle of the Bay is proposed as a ventilation shaft and emergency escape point for maintenance staff. Dissipating heat from the HV cables inside the two sections requires mechanical ventilation, with no precedent in the UK our team conducted in-depth analysis of the air flow pressure drop, noise generation and environmental impact to ensure a feasible and suitable solution was proposed.
Different geological and ground conditions under Morecambe Bay make the construction of the tunnel exceedingly complex. Our engineers worked closely with the team at National Grid to develop bespoke construction methodologies and linings designs. The proposed solution is to lower the specialist tunnel boring machine down the permanent vertical shafts at either end of the tunnel, as the tunnel is drilled it is then lined with concrete and a track laid, enabling a vehicle to get people in and out. The cable system and associated infrastructure is designed around this bespoke mechanised installation methodology. This designs out risk as far as possible and creates a complete solution. The project required an in-depth understanding of marine works and significant multi-disciplinary expertise and experience from our engineers, plus attention to detail in the design.
A complex and innovative project, the tunnel under Morecambe Bay will not only secure the energy supply to the Norh West of the country, but it will set a precedent for all future cable tunnel projects.