A 48-hour Tube strike starting at midday on Wednesday (26 September) will go ahead after last ditch talks between RMT and Transport for London (TfL) fell apart.
The strike will begin at midday on Wednesday, with a further strike planned from 8.30pm on Friday night.
TfL warned that there would be 'little to no service between the afternoon of Wednesday 26 September and the morning of Saturday 29 September', including the Night Tube on 28 September.
Around 500,000 passengers use the line every day
'Customers are advised to complete journeys on the Piccadilly line by 13.00 on Wednesday. Services will resume at around 15.30 on Friday, but will then begin to wind down again from 22.00. Services will then resume to a normal level at around 07.30 on Saturday between Heathrow and Cockfosters and around 08.30 from Uxbridge to Acton Town,' TfL said.
'For customers travelling between Heathrow airport and central London, TfL Rail services will be available to and from London Paddington station every thirty minutes, while Heathrow Express services will also run normally.'
In a statement, the RMT said the industrial action was the result of a 'comprehensive breakdown in industrial relations, abuse of procedures and the reneging on key safety and operational improvements promised by management after previous rounds of industrial action'.
It added that London Underground bosses had 'scuppered ACAS talks by refusing to bring any new proposals or make any serious progress on the core issues at the heart of the dispute'.
RMT general secretary Mick Cash added: 'The attitude of tube managers on the Piccadilly Line has been deliberately provocative and obstructive and it is that stance, including the back-tracking on operational, staffing and safety improvements agreed after previous rounds of action on the line, that led to the current dispute in the first place.
'The attempt by Tube bosses to turn today's talks into a talking shop has deliberately slammed the door on any possible progress and as a result the action starting tomorrow goes ahead exactly as planned.'
However Nigel Holness TfL's director of network operations for London Underground, hit back: 'This strike is unnecessary and will serve only to disrupt Londoners. We have agreed steps with the RMT to solve this dispute and have been making good progress in making these changes.
'I urge the RMT to reconsider this action, withdraw the strikes and spare Londoners and visitors to the city needless disruption.'
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