Ninety-four new "fully walk-through" trains with air-conditioning will replace the current 1970s fleet.
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Overcrowding at West Ham station
Pictures from West Ham station this morning show crowds of people waiting to board the Tube.
There were similar scenes in Canning Town last week. Transport for London said staff absences caused cancellations and delays, and it was not representative of the rest of the Network.
At the weekend, Transport Secretary Grant Shapps urged construction companies to stagger start times to prevent overcrowding.
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Video caption: Footage shows a large crowd waiting to board a Tube train at Canning Town station Northern Line extension holds successful test run
Underground roundels become new shapes at Oxford Circus
The second lockdown may have cut the number of people travelling on the Tube at the moment but those who go through Oxford Circus may have noticed London Underground's famous roundels are now new shapes.
The signs at the central London station have been changed to look like icons on PlayStation controllers to mark the release of the firm's new console.
By Thomas Mackintosh
BBC News, London
By Patrick Cowling
Freedom of Information researcher