Progress on HS2’s Copthall Green Tunnel as Western portal is complete

HS2’s Copthall Green Tunnel has taken a step forward this week, with completion of the western portal.

The 880m long tunnel structure sits between the twin bored Northolt Tunnel and the Colne Valley Viaduct.

'Green' Tunnels

The Copthall Tunnel is one of five green tunnels on the HS2 route, which are shallower tunnels which will be finished with trees, plants and shrubs on top. In turn, this will help them blend into the natural landscape. In addition, materials from the excavation are kept on site and then reused locally, reducing movement of spoil.

So far, the western portal walls, spanning 110m have been completed, along with a further 240metres of walls for the tunnel.

Structure

The team initially excavated around 20 metres down from ground level, before installing piles for the foundations of the tunnel. The structure is then being constructed with a base slab, walls and a roof.

The tunnel is being constructed using reinforced concrete - tied steel bars with concrete poured around to form a strong box structure. This will allow the trains to pass through and enable green landscaping above.

As part of the works in this area, Harvil Road is being realigned, and will travel over the western end of the Copthall Tunnel. The deck for the road realignment is complete and the realigned Harvil Road is due to open in late 2023.

Vital

Malcolm Codling, HS2’s Client Director for the London Tunnels, said:
“The Copthall Tunnel is a vital part of the HS2 route in Hillingdon and once complete will blend into the local landscape as one of HS2’s green tunnels. Our London tunnels contractor SCS JV is making great progress in its construction, all part of the momentum of HS2’s delivery between Old Oak Common and Birmingham.”

The progress continues on the project as HS2 released the first images of the tunnel boring machine (TBM), named Mary Ann’.

The TBM will dig the Bromford Tunnel between Water Orton in North Warwickshire and Washwood Heath in Birmingham.

The name ‘Mary Ann’ comes from the Victorian writer, Mary Ann Evans, who was better known by her pen name, George Eliot.

The TBM’s journey to bore a 3.5-mile tunnel is expected to take around 16 months.

Malcolm Codling, HS2’s Client Director for the London Tunnels, said:

“The Copthall Tunnel is a vital part of the HS2 route in Hillingdon and once complete will blend into the local landscape as one of HS2’s green tunnels.

“Our London tunnels contractor SCS JV is making great progress in its construction, all part of the momentum of HS2’s delivery between Old Oak Common and Birmingham.”