HS2’s Northolt TunnelThe team building the Northolt Tunnel for HS2 have reached a new milestone, completing the construction of 34 cross passages. Cross passages connect the northbound and southbound tunnel and are a safety feature which allows passengers to cross to the adjacent tunnel in the event of an emergency. The Northolt Tunnel is 8.4 miles long, running underground between West Ruislip Victoria Road in Ealing, west London – just outside HS2’s Old Oak Common station. The tunnel was constructed using four tunnel boring machines (TBMs) and the excavation was finished in June 2025. Malcolm Codling, Project Client for HS2 Ltd, said: “The progress made to construct the Northolt Tunnel demonstrates the commitment of our teams to deliver this vital infrastructure efficiently and safely.