Uploaded November 2017 | Updated September 2026, 2 weeks ago

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The four sub-surface lines of the tube - the District, Circle, Hammersmith & City and Metropolitan Lines - are being upgraded to be automatically controlled, as part of TfL's Four Lines Modernisation program (4LM).

We sent Geoff OUTSIDE of London for once to see the works taking place.

More on the TfL website: tfl.gov.uk/travel-information/improvements-and-projects/four-lines-modernisation