NEWS |
HS2 finishes fourth TBM drive for Northolt Tunnel
TBM launch on Macao Light Rail East CHINA - The TBM that will build the northern section of China’s Macao Light Rail Eastern Line was launched in May. TBM ‘Haojiang Pioneer’, built by China
Railway Construction Heavy Industry Corporation Ltd (CRCHI), is to excavate on the 2.74km-long northern section of the line, from Zone A of the Macao Peninsula to the Portas do Cerco (Guanzha Port). The 7.28m-diameter TBM is 87m long,
weighs 690 tonnes and will bore the majority (2km) of the northern section is to be bored by shield tunnel. Shield construction was specified
Above: SCS JV miners from TBM ‘Anne’ celebrate completion of excavation on the Northolt Tunnel, outside London, on HS2 project PHOTO CREDIT: HS2
UK - Excavation of HS2’s Northolt Tunnel was completed at the end of June when the last of four TBMs arrived at Green Park Way in Greenford, west London. TBM ‘Anne’ and three other
Herrenknecht TBMs bored the four tunnel sections that meet at Green Park Way. Northolt Tunnel is a 13.5km-long
twin-bore tunnel that will take HS2’s high-speed trains between West Ruislip, at the outer edge of the capital, and the new Old Oak Common super-hub station in west London. It runs 35m below ground at its deepest point. The tunnel was bored by HS2’s
London Tunnels contractor Skanska Costain Strabag JV (SCS JV). TBM ‘Anne’, named after Lady
Anne Byron, was the second of the pair on the eastern section of Northolt Tunnel, driving 5.5km from North Action to close on the Green Park Way reception shafts. Two other, larger diameter TBMs
built the 8km-long western section, driving from West Ruislip toward Green Park Way. At Green Park Way, each TBM
in turn has been lifted out of its reception shaft using a specially- design ‘steel can’, locked into the
6 | August 2025
shaft wall and able to receive the machine as it build lining up until the end. The solution helps deal with high groundwater and complex geology at the site. The TBM’s 9.11m-diameter sister
machine, ‘Emily’, finished her bore earlier in June. The first two, 9.84m-diameter machines from West Ruislip arrived at the shafts earlier this year. The different diameters of the TBM pairs closing from opposite sides have correspondingly different internal diameters of precast concrete lining - 8.10m in the eastern section and 8.80m in the west, respectively. This is for airflow design as the high-speed trains speed up leaving London. TBM ‘Anne’ was launched in April
2024. Three teams of 48 workers operated the machine around the clock. Best daily performances were approx 38m for the 1,700-tonne TBM. Spoil was withdrawn back at
North Action and taken to HS2’s London Logistics Hub, and sent by rail for reuse across the UK. Precast segments used by TBM
‘Anne’ were made in Hartlepool by Strabag and transported to site by rail.
because the challenges of a densely populated urban area, the narrow construction site. The complex hydro- geological conditions will require multiple TBM launching and receiving operations. CRCHI says this requires precision control of shield machine construction, formation adaptability, and the ability to deal with overlapping risks. CRCHI said the TBM is equipped with
intelligent monitoring, can analyse changes in the soil structure ahead of the face in real-time, and has high-precision deviation correction. The light rail system is improve the
connection between the Portas do Cerco and the Taipa Ferry Terminal.
Second drainage tunnel finish at Athlone IRELAND - A second tunnel beneath the River Shannon has been completed for the Athlone Main Drainage Scheme in Ireland. The TBM bore began from an 8m-deep
shaft on the river’s east bank. Guided by divers and tunnelling crews from Ward & Burke Construction, the machine took 22 days to drive through gravel and rock beneath the riverbed. Uisce Éireann portfolio manager Eunan
Canavan said completion of the second, and final, tunnel was a critical milestone for the project.” Construction work began in 2023. Shaft
construction is now fully complete and cross connection works, to connect the existing and new sewer networks, will continue at various locations around the town in the coming months. The drainage scheme is one of Uisce
Éireann’s largest projects to date and, when completed later this year, will reducing flooding risk and deal with non-compliant sewer overflows into the river, and support population growth.
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