Farringdon is the location of the final main tunnelling work for Crossrail with four out of the eight Tunnel Boring Machines (TBMs) on the entire project ending their journeys there. TBMs Phyllis and Ada which drove the western section have already completed their tunnelling. TBMs Victoria and Elizabeth, are tunnelling from Whitechapel, due to arrive at Farringdon in early 2015 after traversing under the Barbican, probably in January or February according the latest schedule – a couple of months later than planned. They started their journeys in late 2012 so this tunnel section, when finished, will have taken a little over 2 years to drive – a major project by any account.
TBM Elizabeth being lowered into its launch shaft in October 2012 at the start of its journey.
The eventual arrival of the two eastern section TBMs at Farringdon will not only mark the end of their journeys, but also the end of Crossrail’s tunnelling, but there is still plenty of ancillary work remaining before the tunnels can be handed over for commissioning.
The Sprayed Concrete Lining (SCL) tunnelling works at Farringdon are progressing well. Over the next few months Crossrail will continue with the enlargement of the running tunnels into both platform tunnels as well as creating cross passages – the interconnecting tunnels enabling pedestrian access to and from the platforms.
Tunnelling activity is currently taking place from under Cowcross Street, and will progress under the south end of St John Street. It will continue towards Charterhouse Street and then to Crossrail Farringdon’s eastern ticket hall.
Secondary lining of the tunnels will commence at the western ticket hall and progress towards the eastern ticket hall from early 2015. Secondary lining provides further reinforcement and strength to the existing tunnels.
Continual monitoring of the properties above the tunnels is being carried out using prisms and other monitoring equipment fitted to buildings. Grout shafts have been constructed to give further protection to buildings by pumping liquid concrete through the ground to stabilise any ground movement if detected. Crossrail does not expect there to be any damage caused by the tunnelling, but if you need any further information you may visit the Crossrail website http://www.crossrail.co.uk/construction/managing-the-effects-of-construction/ground-settlement-managing-the-effects-of-tunnelling if you can type all that into your computer without a mistake! Visitors to this website will only need to click on the link though.
