Tunnelling is under way this week on the HS2 link between Old Oak Common and Euston, marking a major milestone for the high-speed rail project in London.
The Skanska Costain Strabag (SCS) joint venture will launch the first of two tunnel boring machines (TBMs), named Madeleine and Karen, from the eastern end of Old Oak Common station. The first machine, Madeleine, began the upline drive on Tuesday 27 February, with Karen following next month to excavate the downline tunnel.
Engineers expect the TBMs to advance at rates of up to 150 metres per week, reaching the Euston cavern by late June 2027. The cavern lies around 1km north of the proposed Euston station site, although funding has yet to be confirmed for the final stretch of tunnelling and the station itself.
The Euston tunnels comprise a twin-bore drive of approximately 7.2km, designed to carry high-speed trains between Old Oak Common and Euston. Along the route, the tunnels will sit at depths ranging from around 35 to 50 metres below ground level.
Each TBM measures about 190 metres in length and weighs roughly 1,250 tonnes. Manufactured in Germany by Herrenknecht, the machines were transported to the UK in sections and reassembled at Old Oak Common using a 750-tonne crane within an underground launch box. At the end of their drives, the TBMs’ outer casings will be left in place as part of the permanent tunnel structure, while mechanical components will be dismantled and removed.
As the route approaches Euston, the bored tunnels will transition into spray concrete-lined tunnels, connecting with three additional tunnels to allow trains to enter the station. The SCS team has already completed a logistics tunnel to transport materials and remove excavated spoil from the site, and forthcoming works will include the construction of cross passages between the parallel tunnels.
HS2 has warned that residents near the tunnel alignment may experience groundborne noise as the TBMs pass beneath their properties or during the excavation of cross passages. The project team has said it will provide regular updates as tunnelling progresses.
The extension to Euston, which was revived by the chancellor in the 2024 Autumn Budget, is expected to improve access to central London for commuters while boosting overall capacity on the high-speed network linking the Midlands and the North.
