The RMT union has announced that Tube drivers on the Piccadilly Line will strike in a row over working conditions.
Tube cleaners and some engineers working for Transport for London will also walk out in separate disputes.
Drivers on Tube lines serving the Hammersmith and City, Metropolitan and Circle Lines voted for industrial action, short of a strike.
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The Supreme Court is set to decide on whether disabled travellers are legally entitled to have priority use of wheelchair spaces on buses.