HS2 limited has completed its first so-called green tunnel. The eight hundred and eighty-metre long Copthall tunnel in west London will be used by high-speed trains travelling to and from the capital. Engineers built it using a technique known as cut and cover, which involves digging from the surface, installing the tunnel and then covering it. HS2 will have five green tunnels, named because trees, shrubs and other vegetation are planted on their surfaces.
