HS2’s reveals first completed ‘green’ tunnel
posted on 9th Jul 2026 13:48
The first completed cut and cover tunnel on Britain’s new high-speed railway has been revealed at a site on London’s western periphery. HS2’s 880-metre Copthall ‘green’ tunnel near West Ruislip has been created using 1.2 million cubic metres of material excavated during construction of the line’s nearby twin-bore Northolt tunnel. Originally planned as an open cutting, engineers opted for a cut and cover design. The decision enabled the Northolt tunnel material to be kept on site – negating the need to transport it elsewhere by road in an operation that would have resulted in around 100,000 truck movements.
It is the only ‘single bore’ tunnel on the new high-speed line and its cavernous size is engineered to accommodate the forces generated by 200mph passing trains. The tunnel is built by SCS – HS2’s main civil engineering contractor for the route’s southern section – which is made up of Skanska, Costain and STRABAG.
Copthall is the first of five cut-and-cover tunnels to be completed on the HS2 route between London and the West Midlands – meaning both the tunnel structure and the covering of earth over the top is finished. The next stage of works includes the planting of trees, plants, and shrubs on top to blend into the landscape. The other four green tunnels are also well advanced, with an announcement earlier in July that the structure of Chipping Warden tunnel in Northamptonshire has been completed ahead of works to backfill material.
The milestone underlines the scale of the progress being made on HS2 that will create vital new rail capacity between London and the West Midlands – providing faster and more reliable journeys while releasing space on the crowded West Coast Main Line.
HS2 Ltd CEO Mark Wild is now leading a comprehensive reset of the project to ensure that it is delivered as efficiently as possible and for the lowest reasonable cost. The 140-mile railway is now at a peak construction and significant improvements in productivity have been made over the last year, with six major milestones being reached ahead of schedule.
In May, the Department for Transport confirmed a new delivery schedule and costs for the programme as part of the project’s reset, providing certainty for the taxpayer and local communities. It also announced plans to simplify the railway – operating trains at the same speed as those in Japan and mainland Europe – in a move designed to save up to £2.5bn and cut a year from the construction programme.
