Giant tunnelling machine launched in West Midlands

Dorothy’s name was chosen by local residents and school children via a competition.

A 2,000-tonne tunnelling boring machine (TBM) named Dorothy has been launched in the West Midlands as part of works to build the new High Speed 2 (HS2) railway in the UK.

The 125-metre-long machine, which was built and assembled by 170 engineers, set off yesterday from the north portal of the under-construction Chiltern Tunnel in Warwickshire. It is the first TBM to be launched on the Midlands section of HS2.

HS2 CEO Mark Thurston pushed the button to start the TBM, which was named after Dorothy Hodgkin - the first British woman to win a Nobel Prize for Chemistry. She will excavate a one-mile twin bore tunnel that runs under Long Itchington Wood. 

Dubbed the Long Itchington Wood Tunnel, its construction will preserve the ancient woodland aboveground, which are classified as a Site of Special Scientific Interest and are home to a complex ecosystem that has evolved over centuries.

The final section will form a ‘green tunnel’ - also known as a cut and cover tunnel - where a roof above will return the land to the natural landscape, said HS2.

HS2 CEO Mark Thurston pushes the button to start the TBM on her journey.

Andrew Stephenson, Department for Transport Minister of State for HS2, said, “This is yet another vital landmark in our journey towards a better connected Britain and with the launching of Dorothy today in Warwickshire, shows real progress in helping transform journeys across our country.

“It also underlines how our £96bn Integrated Rail Plan - the largest ever investment in our rail network – is instrumental in creating jobs and economic opportunities, and ensuring more people reap the benefits of better rail journeys.”

Dorothy will be in continuous operation for the next five months and, manned by an “expert tunnelling team” working 24 hours a day in two shifts, she will remove a total of 250,000 cubic metres of mudstone and soil. 

The TBM is currently scheduled to break through the Chiltern Tunnel’s south portal next Spring.

After completing the first bore, Dorothy will be disassembled and taken back to her launch site by road, where she will then be reassembled before setting off on the second bore for the twin-tunnel, which is due to be completed in early 2023.

TBM Florence from Herrenknecht.

While Dorothy is not the first TBM to be launched for the high speed railway project -with just 1 mile of tunnel to excavate beneath the England’s soils - she will be the first to complete her bore.

Her launch comes seven months after that of ‘Florence’ - the largest TBM ever used on a UK rail project - and six months after the launch of Florence’s twin sister machine, Cecilia.

While Florence and Cecilia, which have 10 miles of tunnel to excavate, are being operated by the project’s main works contractor Align (a joint venture formed of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick), Dorothy is being operated joint venture company Balfour Beatty Vinci. 

Built in south-west Germany by Herrenknecht, Dorothy, Florence and Cecilia are the first of ten TBMs that will dig a total of 103km of tunnels for phase one of the HS2 railway network between London and the West Midlands.

Florence and Cecilia during preparations for deployment on phase one of the UK’s HS2 rail project earlier this year.

Mark Thurston, HS2 CEO, said, “You can see the real progress the project is making as we launch this TBM on one of HS2’s largest sites in the Midlands, contributing to massive job creation in the region.

“More than 20,000 jobs and over 650 apprenticeships are already being supported by HS2, which is set to transform transport links between Britain’s major cities, free up space on the rail network for more freight and local services, and support the UK’s transition to net zero carbon emissions.”