The threat of fresh travel disruption caused by industrial action in London has escalated after the capital's Mayor called for an end to "pointless" strikes.
The Rail Maritime and Transport union announced that its members on the Docklands Light Railway will walk out for 48 hours from 3.59am next Thursday in a series of rows including jobs, pensions and hours.
The news came ahead of a 24-hour strike on the Bakerloo and Northern Lines from 9pm on Friday night in separate disputes over two drivers.
London Underground condemned the strike and said it would run Tube services despite the action.
Meanwhile, London Mayor Boris Johnson, who has attacked the recent wave of Tube strikes, revealed that automatic trains have been tested on parts of London Underground.
In a speech in London, he said most of the Jubilee Line currently operates under automatic train operation - from Stratford to Neasden - adding: "In other words the driving of the train is done by computer rather than manually."
He added: "Of course there will still need to be someone aboard the train, but thanks to the advanced signalling being installed it is also a fact that anyone in this room could in a matter of a few weeks acquire the qualifications necessary to supervise an underground train."
Union leaders said the Mayor appeared to be threatening to run driverless trains on the Tube, as happens on the DLR.