Landmark breakthrough for UK Crossrail 11 June 2015

TBM excavation of the 21km of twin running Crossrail tunnels in London is complete. The last of eight 7.1m diameter Herrenknecht machines, TBM Victoria, broke through the head wall at Farringdon Station to complete the western drives and end three years of tunnelling in the process.

UK Prime Minister David Cameron celebrates final breakthrough

Dragados/Sisk underground construction workers were joined in their celebrations by dignitaries including UK Prime Minister David Cameron, London Lord Mayor Boris Johnson, and Transport Secretary Patrick McGloughlin.

The twin drives by TBMs Elizabeth and Victoria launched from the Limmo Peninsula tunnelling site in December 2012, completing their 8,300m journey in approximately 17 months for an average daily advance rate of 16m.

Along the way Elizabeth and Victoria passed through the new Canary Wharf, Whitechapel and Liverpool Street Stations, as well as the Stepney Green caverns where the east–west Crossrail alignment branches north to the portal at Pudding Mill Lane for onward travel to Shenfield in Hertfordshire.

In addition to the 42km of TBM driven tunnels a further 13.5km of new passenger, platform and service tunnels have been constructed within Crossrail’s eight new London stations, using the SCL method.

More than 250,000 concrete segments have been used to line the running tunnels, each weighing more than three tonne. At the height of tunnelling operations the TBMs were advancing at a rate of 100m or more a week, with the best progress in a single day recorded by TBM Ellie – a total of 72m on 16 April last year (2014) during the drive between Pudding Mill Lane and Stepney Green, also for the Dragados/Sisk joint venture.

Credit must also be given to the BAM Nuttall/Ferrovial Agroman/Kier (BFK) JV, which completed the 6,300m Royal Oak–Farringdon drives from the west in October 2013 and January 2014; and to the Hochtief/Murphy JV which completed the 3,000m Plumstead–Woolwich drives under the Thames in January and June 2014 using the project’s only two slurry machines.

Final Crossrail TBM tunnelling progress map

Completion of mechanised tunnelling brings total progress on Crossrail to 65%, and attention now turns to track and station fit out, and M&E installations.

During the construction period so far, more than 450 apprentices have gained work on Crossrail, and more than 8,000 people have undertaken training at the Tunnelling and Underground Construction Academy (TUCA). TUCA opened its doors in 2011 and was created to train a UK underground workforce.

At Prime Minister’s Question Time in the UK House of Commons yesterday (Wednesday 10 June), British Prime Minister David Cameron paid tribute to the thousands of men and women who are helping construct the £14.5 billion Crossrail mega-project, and expressed government support for ongoing alignment, feasibility and business case studies into the proposed north–south Crossrail 2 scheme.