Crossrail Tunnelling - just like Blisworth

Watching the BBC One Show tonight I was taken by the item on constructing  London's Crossrail. The item included lots of information about the size of the project and the usual comparisons with familiar items. This time it was how much water was drained from the dock near Canary Wharf -  it was compared to Olympic-sized swimming pools.

However, what really caught my eye was the wonderful tunnelling machine, or tunnel boring machine (TBM), called Elizabeth. It was shown in action along with the construction of the concrete rings that followed it. Sound familiar? Well yes, it is just like the reconstruction of the middle section of Blisworth Tunnel in the early 1980s. Those of you who have travelled through Blisworth Tunnel will have probably recognised the similarity with the Crossrail tunnel concrete sections, particularly if you have examined the example ring that is on the bank by the South Portal Blisworth Tunnel at Stoke Bruerne.

Blisworth Tunnel

More details of the Blisworth reconstruction, and some good views of its tunnel boring machine and the concrete sections are given on the Blisworth village site. In 2009 it was the 25th anniversary of the reopening of the tunnel. We attended the celebrations and went to the wonderful talk by the two ex-Mowlem engineers that masterminded the project. (See our post about the event)

Although the principle used for Crossrail is the same as for the rebuilding of Blisworth Tunnel, the level of mechanisation and the size are quite different. Crossrail is, of course, larger and much more complex but the removal of spoil is also very different. Still it's good to be reminded how canals took the lead, even in the 1980s, since both the subsequent Channel Tunnel and Crossrail projects used the same tunnelling technique.

Below is an animated Crossrail video about the project. Viewers should be warned there are comparisons with London buses, taxis and jumbo jets! You may be relieved to know that the size of Wales is not mentioned.