The Skanska Costain Strabag (SCS) joint venture has signed a contract for two huge tunnel boring machines (TBMs) that will be used to bore through London clay and chalk for the construction of the southern stretch of the high-speed line.
The TBMs are being built by manufacturer Herrenknecht and will be delivered to site by the end of 2021.
The London tunnels for HS2 are twin bored and will be 13 miles each way. The project will involve tunnelling between central London and the M25.
The two TBMs will be launched from a portal at West Ruislip and will travel 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 will then be 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.
Once the first new TBMs have been built, they will be transported by sea before being delivered to site at the end of 2021. Once assembled, they will begin the tunnel drive from mid-2022, until completion at the beginning of 2024.
Each 140m-long, 2,050t machine will run for 22 months non-stop except for Christmas day and bank holidays. The cutter head will be 9.84m in diameter, slightly smaller than the machines boring through the Chilterns.
Overall, there will be 10 TBMs purchased to construct 64 miles of tunnelling along the HS2 route between the West Midlands and London.
James Richardson, managing director of Skanska Costain Strabag joint venture (SCS JV) said: “As the construction partner responsible for the majority of tunnels on the HS2 project, our contract for the first two TBMs is a major milestone for us. This partnership with Herrenknecht has brought together leading expertise in both our organisations and together we are constructing some of the most advanced TBMs in the world to efficiently drive the tunnels under London.
“Work is already well underway to prepare for the first tunnel launch in 2022. Throughout these and all our activities we are committed to involving local communities and stakeholders and supporting social development and employment through the 4,500 jobs that will be created.”
Malcolm Codling, client director at HS2 Ltd, said: “HS2’s London tunnels will help ensure many homes and habitats in the capital remain undisturbed. 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.
“Building HS2 will showcase Britain’s world class capabilities in tunnelling. The procurement of these incredible machines is an exciting step towards the construction of the London tunnels, which will involve them working 24 hours a day, seven days a week.”