Contract signed for first HS2 TBMs

9 October 2020

HS2 Ltd has announced that main works civils contractor Skanska Costain Strabag JV has signed the contract for the first two tunnel boring machines (TBMs) for London’s HS2 tunnels. The tunnels will be twin bore, each 13 miles long and roughly the same length as the Crossrail tunnels.

To be built by Herrenknecht in Germany, the 9.84m-diameter machines will be designed to excavate through London clay and chalk geology and will be transported by sea for delivery to site by the end of 2021. They will begin boring from mid-2022, until completion at the beginning of 2024.

Starting just outside Euston station, the London tunnels will emerge at Old Oak Common station and then continue from there to the outskirts of West London. Tunnelling between central London and the M25 will be undertaken by HS2 main works contractor Skanska Costain Strabag JV.

Both machines will be launched from the West Ruislip portal and then bore five miles east, creating the western section of the Northolt Tunnel. Once they arrive at Green Park Way in Greenford, the machines will be extracted from the ground and the site used as a vent shaft. The 8.4 mile tunnel will be completed with a 3.4 mile tunnel drive from Old Oak Common using two further TBMs which are yet to be procured. A second tunnel between Euston and Old Oak Common will complete the remaining 4.5 miles of London tunnel between the two HS2 stations.

To build the 64 miles of tunnel for the route between London and the West Midlands will require a total of ten TBMs.

“HS2’s London tunnels will help ensure many homes and habitats in the capital remain undisturbed,” said Malcolm Codling, Client Director at HS2. “This is a key part of our commitment to deliver Britain’s new high-speed railway in the most environmentally-friendly way and minimising disruption to our neighbours.”

The TBMs will operate 24/7 for 22 months except for Christmas day and bank holidays. Each 9.84m-diameter cutterhead weighs around 2,000t and together they will excavate around 1.2 million cubic metres of spoil.