Inside London’s deepest HS2 tunnel: 34 hidden passages revealed

Take a look inside the HS2 Northolt Tunnel as engineers complete all 34 cross passages deep beneath London. This major milestone brings the UK’s new high-speed railway one step closer to operation. The team constructing the 8.4-mile-long Northolt Tunnel for HS2 has successfully completed all 34 cross passages - critical safety links connecting the northbound and southbound tunnel bores. These passages allow passengers to safely move between tunnels in the event of an emergency, forming a vital part of the railway’s safety systems. Running between West Ruislip and Old Oak Common in west London, the tunnel reaches depths of up to 35 metres below ground. It was excavated using four tunnel boring machines, with tunnelling completed in June 2025. 👉 In this video, see how engineers constructed these cross passages using spray concrete lining (SCL), carefully excavating between tunnel bores spaced 6 to 20 metres apart. 📢 Subscribe for the latest news and updates from Britain’s high-speed railway, HS2. Follow us on social media: 💼 X:   / hs2ltd   📸 Instagram:   / hs2ltd   📘 Facebook:   / hs2ltd   🔗 LinkedIn:   / high-speed-two-hs2-ltd   #HS2 #Train #Rail #Infrastructure #Construction #HighSpeedRail #Engineering Get in touch: If you have any questions about HS2 or our ongoing works, contact our HS2 Helpdesk team: 📞 Call: 08081 434 434 📧 Email: [email protected]