With less than one hundred days to go before the first tunnel drive on the Crossrail project, Crossrail has finally unveiled the first of its giant tunnel boring machines. The TBM is now fully assembled and is currently being put through some rigorous tests at the factory in Germany before it is dismantled once again and shipped to the UK in time to begin tunnelling.

Crossrail will be using a total of eight tunnel boring machines to complete the tunnelling section of the Crossrail project, all of which are being constructed by Herrenknecht AG. This is the same German company that was responsible for supplying tunnel boring machines to work on the Docklands Light Railway Extension project as well as the Jubilee Line extension.

The first stage of tunnelling is scheduled to begin in March next year and the first of the Crossrail TBMs will begin tunnelling at the Crossrail Royal Oak portal. Another tunnel boring machine will also be sent underground from the Royal Oak portal a few weeks after the first TBM. Further tunnelling launches will commence from Limmo Peninsula at the end of 2012, and thereafter there will be TBM launches in 2013 and 2014.

In total, there are ten separate tunnel drives planned for the Crossrail route and by the time the tunnel boring machines have completed their mammoth schedule of work, 21 kilometres of tunnel will have been bored beneath London. The completed tunnels will be 6.2 metres in diameter and as each TBM progresses slowly, pre-cast concrete rings will be put in place behind them. In order to ensure there is a ready supply of concrete for the Crossrail project, a concrete segment factory has been built at Old Oak Common. Once tunnelling is underway, the tunnel boring machines will be working 24/7 with no breaks expect for scheduled maintenance work.

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