I’ve recently been watching a documentary on the building of Crossrail. Generally, civil engineering isn’t really my bag but somehow I was convinced to watch this. The scale of the Crossrail construction is immense; 73 miles of track with a marathon length of tunnel and 10 completely new stations.
The most interesting part was viewing the path of the tunnel through Soho. As London is so built up and effectively full, there are so many obstacles for the tunnel boring machine (TBM as it’s known in the trade) to avoid. The tunnel will be 6 meters wide and there is a point at Tottenham Court Road dubbed the eye of the needle. Here is the tightest point the 26 mile tunnel has to pass through.
At this point the 6 meter tunnel is built in a space 85 cm above the Northern line platform and only 35 cm below one of the escalators at Tottenham Court Road station.
When the man and I heard these stats we almost fell off the sofa. We knew the passage had been successful but the tension as the TBM passed through the eye of the needle was huge, it was as if we were watching an action movie.
Yes, perhaps I do need to get out more.