HS2: First of six giant tunnel boring machines (TBMs) begins its journey under London


HS2, London, TBM, tunnelling,


The next tunnelling phase begins for HS2 as Skanska Costain STRABAG JV launches Sushila, the first TBM to dig over 26 miles of tunnels under London.

HS2 Ltd’s CEO, Mark Thurston, was joined by a  local teacher, Sushila Hirani, after whom one of the tunnel boring machines at the West London site is named, as it begins its five-mile journey.  

“Sushila” is the fourth of ten HS2 tunnel boring machines to be launched. The milestone highlights the progress of building Britain’s new high-speed rail network, creating jobs and providing business contracts.  

Later this year, a second TBM, named after 18th-century astronomer Caroline Herschel, will be launched from the West London site to build the second of HS2’s twin-bore tunnels towards central London.  

Already well underway, HS2 is set to revolutionise journeys for communities throughout the country, boost local economies, and its peak, support more than 34,000 jobs across the UK,” says HS2 Minister Kevin Foster MP. 

Each weighs over 2,000 tonnes and measures 140 metres in length; both TBMs will bore five miles non-stop for 22 months, except Christmas Day and bank holidays, to Greenpark Way in Greenford, where they will be dismantled and lifted from the ground.  

Separately, two other equally massive tunnel boring machines will set off towards Greenpark Way from HS2’s Victoria Road site in 2023 to build a further 3.4mile twin-bore tunnel. Together the quartet of TBMs will make 8.4miles of twin bored tunnels between West Ruislip and the new high-speed rail super hub station at Old Oak Common.     

Another 4.5-mile twin-bore tunnel from Old Oak Common to Euston will complete HS2’s journey to its London terminus.  

Each TBM is operated by fifteen people working in shifts. A team of around 40 assembled the TBMs, with 56 companies involved in getting the site ready and machines launched. 

The ten TBMs will create 64 miles of tunnels on HS2 between London and the West Midlands. 

The construction of 170 miles of a new high-speed railway between London and Crewe is now in full swing, supporting 27,000 jobs, nearly 1,000 apprenticeships and contracts for over 2,500 businesses,” says HS2 CEO Mark Thurston. 

We have started on one of the most complex parts of HS2, tunnelling from here we at West Ruislip towards Euston beneath one of the busiest cities in the world. The huge team effort has enabled some of the most advanced tunnel boring machines ever built to be launched. Our team has brought together world-class skills and developed many new people to the industry working on this crucial national infrastructure project,” says Managing Director of Skanska Costain STRABAG JV James Richardson. 

Local school children from Dairy Meadow Primary School in Southall and Brentside Primary Academy helped name the TBMs after participating in workshops about the tunnelling work. The TBM launched today is called Sushila after local schoolteacher Sushila Hirani, Head of Department and Lead for STEM at Greenford High School. The Willow class at Dairy Meadow Primary School in Southall suggested the name due to her inspiring work and passion for getting more women and young people from BAME backgrounds into STEM subjects.   

With a background in product design, Sushila has been a teacher for nearly 30 years. Her involvement in local infrastructure and development projects, including the Waterside housing development in Southall, and drive to attract girls into STEM subjects as a path towards Engineering at A Level, apprenticeships, and degrees has inspired many in the local area.  

The second TBM to be launched has been named Caroline after the German-born British astronomer Caroline Herschel. Considered the first professional female astronomer, discovering three new nebulae (hazy clouds where stars form) in 1783, Herschel became the first woman ever to find a comet in 1786. She made significant contributions to the work of her astronomer brother Sir William, executing many of the calculations connected with his studies.  She compiled a catalogue of 2500 nebulae, and in 1828, the Royal Astronomical Society awarded her its gold medal for this work. Her name was put forward for the TBM by pupils at Brentside Primary Academy in Ealing. They were inspired by her contribution to astronomy whilst learning about earth and space in their science lessons.   

Sushila and Caroline will be operated by Skanska Costain STRABAG JV (SCS JV). Worldwide, TBM specialist Herrenknecht in Germany manufactures the machines.    

Further facts about the TBMS:  

  • Each machine is 140 metres in length, one and a quarter times the length of a football pitch  
  • Each has a cutter head that is 9.84m in diameter, slightly smaller than the machines boring through the Chilterns   
  • They each weigh approximately 2,050 tonnes, roughly the weight of 20 blue whales  
  • 1.2 million cubic metres of excavated material will be removed, weighing 2.46 million tonnes  

Source: © High Speed Two Ltd 2022

Image source: © High Speed Two Ltd 2022

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