Major components of the first of the second pair of Herrenknecht EPBMs that will bore HS2’s 13.4km long Northolt High Speed Rail Tunnels under London have now been lifted into the 25m deep ancillary shaft at the HS2 site in Ealing in preparation for launch. HS2’s London Tunnels contractor, Skanksa Costain STRABAG joint venture completed the lift as they prepare for the next stage of tunnelling under the capital.
Named Emily and Anne, the two TBMs weigh 1,700 tonnes each. After being lowered underground into the launch chambers in pieces, they will be reassembled. Each part of the TBM is lifted using a crane, including the 316-tonne front shield and 336-tonne middle shield. Eight back-up gantries for each machine will also be lifted into place to provide all the systems required for the tunnelling operations underground.
The machines are designed specifically for the soft ground conditions, specifically London clay.
The machines will begin the 5.4km journey at the start of 2024, travelling under Ealing from the Victoria Road site towards Greenpark Way in Greenford, taking around one year to complete the journey. At Greenpark Way, the machines will be disassembled and removed via another 35m deep shaft.
James Richardson, Managing Director of Skanksa Costain STRABAG joint venture, said:
“The London Tunnels programme is reaching its peak delivery stage and we’re excited to name our next two TBMs, Emily and Anne. They will join our first two TBMs, Sushila and Caroline, who are already one year into constructing the section of tunnel between West Ruislip and Victoria Road.
“We are well on the way to delivering the high speed tunnels into London. Next year we’ll be assembling our final two TBMs that will tunnel between Old Oak Common and Euston.”
The Northolt tunnel is being built in two sections. Two TBMs are already boring the western end of the tunnel beginning in West Ruislip working towards Greenford with almost 3.2km completed so far. The two new TBMs will bore the eastern section. The final section of tunnel from Victoria Road Crossover Box to connect to Old Oak Common Station will be constructed using spray concrete lining.
Before the launch of the TBMs, a blessing ceremony conducted by a local priest will be held – a longstanding tunnelling tradition. A statue of St Barbara, the Patron Saint of tunnelling, will be blessed and placed at the entrance of the tunnel.