Crossrail has cast the last of the 250,000 concrete segments that are being used to line the tunnels under London.
The final piece was cast at a dedicated Crossrail factory in Chatham, Kent, where 110,000 tunnel segments to line Crossrail’s 12km long eastern twin tunnels, from east London to Farringdon were produced.
Segments for the western tunnels from Royal Oak to Paddington were manufactured at a separate facility at Old Oak Common — which you can read about here.
Segments for the Thames Tunnel between Plumstead and North Woolwich were manufactured in Ireland.
At peak, the Chatham factory operated 24 hours a day, five days per week and on average manufactured 330 segments per day. Each segment weighs 3.4 tonnes. Seven segments and a keystone form a complete tunnel ring in the new Crossrail eastern tunnels, which are being built by joint venture Dragados Sisk.
It’s worth noting that none of the segments are straight — they all curve slightly to the left, or the right, and if the tunnels need a straight line, they alternate, so the tunnels imperceptibly wobble a tiny bit along their length.
The Chatham factory sustained 120 jobs for local people, including two apprentices. Maidstone-based Brett Concrete supplied 140,000 cubic metres of concrete for the segments and Medway Ports facilitated 260 river barge movements from Chatham to Limmo Peninsula, near Canning Town, where segments feed Crossrail’s tunnel boring machines.