TRANSPORT | RAIL PROJECTS - HS2


CELEBRATING FINISHES HS2 -


The start and completion of a tunnel is always to be celebrated, and recently the HS2 project has enjoyed a flurry


Over recent months, the HS2 project has had


opportunities for a number of celebrations as drives on many of the large-diameter rail tunnels were completed. Those TBM drives took place outside of central London, where more tunnelling is yet to be done. At the edge of London, in the Chilterns and up near


Birmingham, many different tunnel drives were required, and completed, for the twin-tubes of the high speed rail project. Those TBMs on Phase 1 that are finished have been dismantled.


It is rare for so many large TBMs to be active in the


UK, and even moreso outside of London, and also for them to be completing their bores within relatively tight windows. The TBM drives so far and their finishes are briefly


described below. More are to come, in London, with two TBMs on the Euston Tunnel. Works for the latter were enabled by construction of the Atlas Road Logistics Tunnel, which was completed early 2024. The project also includes some cut-and-cover ‘green’ tunnels.


EDGE OF LONDON HS2’s 13.5km-long Northolt Tunnel was nearing completion of boring by mid-year when the fourth, and last, TBM on this section of the project would arrive and finish its journey at the Green Park Way site, in Greenford, west London. The Green Park Way site sits along Northolt Tunnel,


resulting in the tunnelling works on either side. To the west side is a for the twin-tunnels to be arranged in two groups: to the west is the 8km-long, 8.80m-i.d. western section from West Ruislip; and, to the east is the 5.5km-long, 8.10m-i.d. section that runs closer to London, to North Acton. Northolt Tunnel is one of five deep twin-bore tunnels


on HS2’s 225km-long route. It is the second longest tunnel on the project and runs up to 35m below ground at its deepest point. This section of HS2 extends from West Ruislip via North Acton to new Old Oak Common super-hub station. Contractor is Skanska Costain Strabag JV (SCS JV). It is also building the Euston Tunnel, in central London.


Above: Tunnel excavation at Euston, in late 2024 IMAGES COURTESY OF HS2


22 | August 2025


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