Update on Northolt Tunnel construction
Work item: HS2-EW-SCS-Ph1-Ar-So-S1 -Tun-1-08/05/25
Work Item Summary
- Project Phase
- Phase 1
- Region
- Brent and Ealing, Old Oak and North Acton
- Location
- Northolt
- Worksite Name
- Northolt Tunnel East
- Contractor
- SCS JV
- Type of works
- Construction, Tunnelling
- Estimated Start Date
- 31/08/2022
- Estimated End Date
- 30/09/2026
What we are doing
The Northolt Tunnel is 8.4 miles (13.5km) long between Old Oak Common station and West Ruislip, where the HS2 route surfaces.
The tunnel is being built in two phases, known as Northolt Tunnel West (NTW) and Northolt Tunnel East (NTE). These are being built by four Tunnel Boring Machines (TBMs).
Our NTW TBMs have completed their journeys. TBM Sushila, reached Green Park Way Vent Shaft in December 2024 and TBM Caroline arrived in April 2025. With the NTW tunnelling now completed, works have begun to remove the structures and equipment needed to support tunnel construction at the West Ruislip Portal in Hillingdon.
Our NTE TBMs, Emily and Anne, are expected to finish their journey at Green Park Way Vent Shaft by the end of June. Works will continue in Old Oak Common to build the sprayed concrete lining tunnels between Victoria Road Crossover Box and Old Oak Common Station.
Cross Passages
Cross passages (CP) are short tunnels connecting the two running tunnels to provide a safe evacuation of trains in an emergency. These will be built approximately 500 metres apart along the tunnel route and will be between 12 to 40 metres below ground.
We have eight cross passages remaining to build across both tunnel phases. Details of upcoming five construction and approximate locations can be found below.
| Date* | |
| NTW CP 17 Station Approach | 9 May 2025 |
| NTW CP 18 Fairway Drive | 22 May 2025 |
| NTE CP 11 Bideford Avenue | 14 May 2025 |
| NTE CP 12 Selborne Gardens | 30 May 2025 |
| NTE CP 13 Woodhouse Avenue | 11 June 2025 |
| *All dates are subject to change. Updates can be found on HS2inBrent&Ealing.org.uk closer to the time of construction | |
Boreholes
As part of our continued investigative work, we are routinely checking the boreholes along the route. Some of the boreholes are located in open spaces in the local area and you may see our operatives carrying out checks on a daily basis.
Monitoring and surveys along the tunnelling route
We will carry out ground and building monitoring and visual surveys along the tunnelling route. You may notice our surveying team in your local area for short periods. We will let you know if any of our monitoring and visual surveys will impact you directly.
Engagement events
Virtual Future Tunnelling Drop In Every third Tuesday of the month, except December – Virtual Drop-ins: HS2 & SCSJV Tunnelling Works
Northolt Tunnels in person drop in event, 9 June 4:30pm – 7pm – HS2 and SCSJV event: Northolt Tunnels – HS2
For further details please see notification below.
Download information relating to these works
Find out more about
If you have a question about HS2 or our works, please contact our HS2 Helpdesk team on 08081 434 434 or email [email protected]