A tunnel borer in use during Piccadilly Line extension work - photograph

The Piccadilly line was extended in 1977 to link with Heathrow airport. Tunnels were dug using boring equipment known as tunnelling shields. These had power-driven 'boom cutters', which broke up and cut through the clay soil. Once the shield had bored a stretch of tunnel, it supported it while reinforcing work was carried out. This construction worker is adjusting the controls of the shield, which has just broken through the concrete wall to Heathrow Central station.
Production Date:
6 May 1974
ID no:
Photographer : LT Advertising and Publicity
Transport for London

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