Hundreds of traffic jams have been reported in London with 200 miles of tailbacks as the capital was hit by travel chaos because of a strike by London Underground workers.
Tube services ground to a halt last night and will not return to normal until tomorrow morning, forcing commuters and tourists to walk or cram on to packed buses.
Members of four unions are taking industrial action for the second time in a month because of a deadlocked dispute over plans to launch a new all-night Tube service next month.
Extra buses were laid on but there was huge disruption, with roads gridlocked as people switched to cars.
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.
The most congested roads were around Parliament Square (delays of 48 minutes) and on the A40 from Wood Lane to Marylebone Road (30 minutes).
"With many Londoners away on holiday and no school runs, the roads were not as congested this morning as they were during the last strike four weeks ago," said a TomTom spokesman.
The dispute over pay and conditions for the planned night Tube has worsened in recent days, with more workers being balloted for action and London's mayor making it clear no more money will be offered.
Staff on the Docklands Light Railway, London Overground, the bus network, tram and TfL Rail services are not on strike.
These services ran as normal, but they were much busier than usual and people were strongly advised to travel outside the morning and evening peaks.
TfL had more than 600 "travel ambassadors" on hand to help Londoners, visitors and tourists get to their destinations on foot, by bus, bike or other means.
Around 250 extra buses are being provided and there will be more river services.
Mayor Boris Johnson said he was "not fussed" about the new service starting on time on September 12.
"I want it starting in the autumn - what I am fussed about is the offer being put to union members.
"I am not going to authorise any more money. Most people would recognise that this is a very generous deal."
Aslef general secretary Mick Whelan said: "Our members have rejected the latest offer from the company because they are forcing through new rosters without agreement and offer no firm commitments on work/life balance for train drivers."
RMT leader Mick Cash said: "The offer tabled by London Underground is just a rehash ?of an earlier package and does nothing to tackle the fundamental issue of our members being called into work at the beck and call of management to plug staffing gaps in the mayor's botched night Tube plans."
Steve Griffiths, London Underground's chief operating officer, said: "I am sorry that the unions have rejected our extremely fair offer outright and that the journeys of our customers will be disrupted today. We have a volunteer army of hundreds on hand to help London's workers, residents and visitors get around during the strike. I thank customers for their patience as they make their journeys today.
"We have made every effort to reach agreement with the unions and avoid this unnecessary strike action. We have employed 137 new drivers and 345 new station staff for the night Tube service.
"We've made work/life balance guarantees that no one will work extra hours and that drivers will have the same number of weekends off as now and will be able to choose whether they work night Tube shifts in future."