The dispute over London Underground ticket office closures was deadlocked tonight with millions of commuters almost certain to be caught in the crossfire.
Peace talks at the conciliation service ACAS broke up without agreement after the unions rejected a last-minute offer from LU bosses.
Underground negotiators proposed a 'cooling off' period until March 5th. LU said it would halt the ticket office closure programme if the unions suspended the strike.
But RMT leader Bob Crow said the strike would go ahead and he called on union members to "stand shoulder to shoulder."
In a message to tube workers Mr Crow said: "Despite the best efforts of your negotiators, who have spent over seven days at ACAS trying to resolve the matter, management has refused to budge.
"They have refused to stop seeking volunteers during the consultation period which makes a mockery of the whole process."
London Underground claims 1,000 tube workers have requested a quote for voluntary redundancy and 450 have made formal applications to leave.
The ticket office closures will lead to the loss of 950 jobs, although 200 new posts will be created when the so-called Night Tube is introduced next year.
LU Chief Operating Officer Phil Hufton said: "It's not too late for the RMT and TSSA to call off their unnecessary strikes and work with us to shape the future of the Tube.
"We remain ready to continue talks at any time."
The 48-hour strike is due to start at 9pm tomorrow with most disruption expected on Wednesday and Thursday.