London was hit by travel chaos because of a strike by London Underground workers, with worse disruption threatened unless a deadlocked row over all-night Tubes is settled.
Hundreds of traffic jams were reported, with 200 miles of tailbacks in the morning rush hour, while huge queues built up for buses and trains as people tried to get to and from work.
Tube services ground to a halt last night and will not return to normal until tomorrow morning because of a walkout by members of four unions.
Mayor Boris Johnson was urged to intervene in the dispute, which is set to escalate if an agreement cannot be reached.
Unions will meet next week to decide their next move, which could include a 48-hour strike, hitting the capital in the middle of the busy tourist season.
The RMT union said rotas drawn up for the new night Tube, set to start on September 12, were the "rosters from hell" which would disrupt the work-life balance of staff.
General secretary Mick Cash said: "It has become clear that Boris Johnson has taken direct control of the current Tube dispute.
"As the night Tube is his personal project, and as chair of Transport for London, it is now time for the Mayor to reverse his long standing policy of not meeting with the trade unions and to give our negotiators an opportunity to set out the facts to him directly.
"From the Mayor's statements it is clear that he has not got the message that this dispute is not about money it is about work/life balance and it is essential that with Mr Johnson now taking charge of the dispute that he grasps the fundamental issues."
TSSA leader Manuel Cortes said: "This is too serious for the Mayor to simply wash his hands of it and leave it to his negotiating team. We want to deal with the organ grinder, nobody else.
"No one wants to see London at a standstill but we want our members to enjoy a proper work-life balance, like other Londoners who enjoy quality time with their families at the weekends."
At 8.45am there were 428 separate traffic jams causing 197 miles of tailbacks, according to traffic experts at TomTom.
That was double the congestion at the same time last Thursday, although not as bad as the previous Tube strike a month ago when there were 1,445 jams and 761 miles of delays.
TfL had more than 600 "travel ambassadors" on hand at stations, giving alternative travel information to people who usually use the Tube.
Boris Johnson, who has said he was "not fussed" about the new service starting on time on September 12, accused the unions of "holding a gun" to the heads of the travelling public.
Steve Griffiths, London Underground's chief operating officer, said: "We thank our customers for bearing with us during this unnecessary strike action. I am sorry that many people's journeys have been difficult, but we are doing everything we can to get our customers around by other means. We are also taking advantage of the fact no trains are running by making progress with engineering work.
"We have made a very fair offer to the unions that includes pay rises and bonuses for all, and guarantees to protect work-life balance. With the drivers, station staff and other roles which we have recruited for the night Tube it is also creating over 500 jobs.
"We now ask them to engage properly in negotiations to get past this dispute and deliver the night Tube that London needs. We remain ready to talk at any time."
Talks between the two sides are expected to resume next week.