HS2 launches its first TBM as tunnelling begins in the Chilterns

Posted on 13 May 2021

High Speed 2 (HS2) construction takes a big step forward today with the launch of the project’s first tunnel boring machine (TBM) from the South Portal site next to the M25 in Buckinghamshire.

The 2,000t TBM – named Florence – is the first of 10 that will dig 102km of tunnels for the high speed rail line.

It will dig the first of a pair of 16km-long tunnels under the Chiltern hills and help to safeguard the woodland and wildlife habitats above ground. A second machine, Cecilia, will launch next month to excavate the second tunnel at the South Portal site.

The TBMs will be operated by HS2 main works contractor Align– a joint venture of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick.

Designed specifically for the mix of chalk and flints under the Chilterns, the two identical TBMs will dig separate tunnels for north and southbound trains.

Each machine operates as a self-contained underground factory - digging the tunnel, lining it with concrete wall segments and grouting them into place at a speed of around 15m a day. Each tunnel will require 56,000 precision engineered, fibre-reinforced segments, which will all be made on site.

A crew of 17 people will operate each TBM, working in shifts to keep the machines running 24/7. They will be supported by over 100 people on the surface, managing the logistics and maintaining the smooth progress of the tunnelling operation.

Chalk excavated from the tunnels will be used for landscaping at the south portal site once construction is complete, creating wildlife-rich chalk grassland habitats across 127 hectares of the southern Chiltern hills.

Built by Herrenknecht at its factory in south-west Germany, the two 170m long machines were transported to the UK in more than 300 separate shipments last year, before being reassembled, tested and commissioned by an expert team of tunnelling engineers.

Transport Secretary Grant Shapps said it is a “landmark moment” for the project which highlights the commitment to levelling up transport links across the UK.

“The work has truly begun on taking HS2 northwards," he said. "The tunnels these machines dig will ensure the benefits of our new high-capacity, high-speed railway run to the great cities of the North and Midlands, forging stronger connections in our country, boosting connectivity and skills opportunities and transforming our transport links.”

HS2 Ltd Chief Executive Mark Thurston also welcomed the progress, describing it as "a moment of genuine excitement".

“The launch of our first tunnelling machine is a major moment of progress for the HS2 project as we work to deliver a high-speed railway that will offer low-carbon alternatives for long distance journeys across the UK,” he said.

Meanwhile, HS2 minister Andrew Stephenson described it as a “truly historic moment”.

He said: “Supporting over 16,000 skilled jobs and hundreds of apprenticeships, and thousands of contract opportunities for British businesses, HS2 is a job creator, a spark for economic growth and an opportunity to level up the country, right at the heart of our plans to build back better from Covid-19.”

Align project director Daniel Altier added: “Align is very proud to be launching the first two TBMs on the HS2 project. The TBMs include a number of innovations to improve efficiency and the safety of the environment in which the crew will be working, that have never before been introduced on any previous TBMs, worldwide.

“I would like to thank everyone in our integrated project team that includes Align, our design partner Align D and HS2, working closely with our suppliers, for all their hard work that has enabled us to get to where we are today, culminating in the launch of Florence.”

#hs2 #infrastructure #civilengineering #tunnelling #majorprojects

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