photo: https://mediacentre.hs2.org.uk/news/embargoed-historic-moment-as-hs2-launches-first-giant-tunnelling-machine/TBMs complete the first phase of HS2 tunneling, the goal is to be a tunnel 103 kilometers long
The first phase of the HS2 tunnel covering the distance between the Chilterns south portal and the first ventilation shaft at Chalfont St. Peter has been completed at last.
The Chalfont St. Peter shaft (78 m deep) was the first of five shafts that will provide emergency access and ventilation to the 16 km long tunnels, the longest on the project. So far, the two tunnel boring machines (TBMs), Cecilia and Florence, have dug a total of 5.8 km, completing the first phase of the project. The TBMs installed more than 20,000 individual segments of fiber-reinforced concrete walls, each weighing about 8.5 tons. In total, each one of the tunnels will require 56,000 such segments.
Cecilia and Florence are operated by Bouygues Travaux Publics Sir Robert McAlpine and Volker Fitzpatrick, which are part of the Align joint venture. A total of 10 TPMs are planned to be involved, creating a 103 km long tunnel between London and the West Midlands. The main tunnels on the approach to London and Birmingham (the first phase of HS2) are expected to begin commercial operation between 2029 and 2033.
The material excavated during construction will be used to improve the southern portal site. It will help create approximately 90 hectares of chalk grasslands, which are now considered a habitat of international conservation importance. Nowadays, there are only 700 hectares of them left in Chilterns.
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