HS2 Ltd has announced the launch of the enormous 2,000 tonne tunnel boring machine (TBM) ‘Florence’ from HS2’s South Portal site next to the M25 in Buckinghamshire, the the first of ten giant tunnelling machines that will dig 64 miles of tunnels between London and the West Midlands.
The first two Tunnel Boring Machines (TBM) will be operated by HS2’s main works contractor, Align, the TBM has been 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 15 meters 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, a world leader in TBM manufacturing, 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 at the Chiltern tunnel south portal site, near the M25 to the north-west of London.
The names of the two TBMs were suggested by students at Meadow High School in Hillingdon and The Chalfonts Community College, Buckinghamshire, which are close to the tunnel launch site. They were inspired by Florence Nightingale, the founder of modern medicine, and pioneering astronomer and astrophysicist, Cecilia Payne-Gaposchkin.
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