Northolt tunnel

Northolt Tunnel is a high-speed railway tunnel in Greater London, England, that will carry the High Speed 2 (HS2) railway line under the West London suburbs. The twin-bore tunnels were excavated from October 2022 until June 2025 and run for 8.4 miles (13.5 km) between Old Oak Common and Ruislip. Plans for the construction of a tunnel were first unveiled in early 2013; it was hailed as being less disruptive and quicker to construct than a surface-based alignment. An option for the tunnel's extension along the Colne Valley to replace the proposed Colne Valley Viaduct was studied but rejected as unnecessarily costly during 2015. Extensive ground surveys along the intended route were conducted during the 2010s in advance of construction work. During April 2020, it was announced that a contract worth approximately £3.3 billion had been awarded to a joint venture company, Skanska Costain Strabag, for the tunnel's construction.

Tunnel data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).