HS2 completes first ‘green’ tunnel as Copthall milestone reached

HS2 has reached a major construction milestone with the completion of the 880-metre Copthall Tunnel near West Ruislip, marking the project’s first completed ‘green’ tunnel.

Delivered by the Skanska Costain STRABAG Joint Venture (SCS JV), the cut-and-cover tunnel has been designed to reduce environmental impacts while supporting the delivery of Britain’s new high-speed railway.

One of the project’s biggest sustainability achievements saw 1.2 million cubic metres of excavated material from the nearby Northolt Tunnel reused to construct the tunnel, eliminating an estimated 100,000 HGV journeys.

Once complete, the structure will be covered with soil and planted with trees and shrubs, allowing it to blend into the surrounding Colne Valley landscape. The design was also changed from an originally proposed open cutting to a cut-and-cover solution to deliver these environmental benefits.

The completion of Copthall Tunnel represents another significant milestone for HS2 as major civil engineering works continue across the route.

The project showcases how sustainable construction methods, material reuse and environmental design can be integrated into large-scale infrastructure delivery.

As construction progresses, HS2 continues to provide substantial opportunities across civil engineering, rail infrastructure, environmental management, landscaping and the wider construction supply chain.