HS2 launches second Chiltern Tunnel TBM

2 July 2021

Following the recent launch of TBM Florence to excavate the first tube of the 16km-long Chiltern Tunnels, HS2 has now launched the second machine, Cecilia, from the South Portal site northwest of London.

Align Project Director Daniel Altier said: “We are delighted to be launching Cecilia…, the second of our TBMs, to dig the Chiltern tunnels. Both TBMs are identical and include innovations to improve efficiency and the safety of the environment in which the crews will be working that have never before been introduced on any previous TBM worldwide.”

HS2 said that despite Cecilia starting second, the 2,000t machine will bore at a slightly faster rate than her sister, so both machines will break through at around the same time. Operated by a crew of 17, both machines are powered by zero-carbon electricity and advance at up to 15m/day, installing a total of 112,000 fibre-reinforced segments which are being manufactured onsite.

The two TBMs are excavating separate northbound and southbound tunnels through the chalk and flint geology of the Chiltern Hills, recognised as an area of outstanding natural beauty. Launched from the site by the M25 motorway, the two machines are operated by HS2’s main works contractor, Align – a joint venture comprising Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick.

Welcoming the news of the launch, HS2 Ltd’s Delivery Director, David Bennett said: “With more than 16,000 jobs already supported by the project and thousands of companies big and small benefiting from contracts, HS2 is providing a major boost to the economy in these difficult times. In the longer term, this transformational rail project will help link our regions and nations and offer low-carbon transport options for generations to come.”