A 24-hour strike on the Tube has ended, but services are not expected to be back to normal until Thursday morning.
Many people followed advice to walk from mainline stations
Rush hour commuters faced a struggle to get home as much of London Underground (LU) shut down in a dispute over pay and conditions.
LU said one in four trains was running by the afternoon and an extra 1,000 buses had been put into service.
Some commuters stayed home, some walked and seven million crammed onto buses - the highest number since 1950.
A full service is not expected to resume until 0500 BST on Thursday.
Thousands of Tube staff, including drivers and signallers, took part in the walk-out organised by the Rail, Maritime and Transport (RMT) union.
The RMT described the action as "100% successful" and said it had been solidly supported by its 7,500 members.
Allow extra time for journeys and try to travel outside rush hour
No additional parking and the £5 congestion charge still applies
A free river service will run during rush hour
In the morning rush hour, there were only about 80 of the usual 500 trains, but by the afternoon LU said one in four were running.
But the RMT claimed managers were exaggerating the number of services and the Tube had been "crippled".
RMT general secretary Bob Crow said: "We hope the company will look at its position and get round the table and negotiate a settlement that is acceptable to our members.
"Obviously if the company doesn't negotiate seriously we will have to look at putting more action on."
TfL said every available bus, an extra 1,000, had been "scrambled" to help take an extra one million Tube commuters who switched to the bus service.
The river service was free during rush hour and the Docklands Light Railway (DLR) and trams were still running.
But some people appear to have risked the roads, as the AA reported routes into London were busier than usual.
On the Victoria Line, which was running, many trains were half empty as passengers made alternative arrangements.
Anger as workers battle to get across the capital
A spokesman for London Chamber of Commerce and Industry said it was too early to say how many people had taken the day off or worked from home.
But he added that on previous Tube strikes more than 50% of people chose not to go into work.
The cost to London's economy has been estimated at between £60m and £100m in lost productivity and fares.
The RMT called the strike because of a row over pay and conditions.
It is partly linked to Mayor Ken Livingstone's attempts to "modernise" the Tube with new technology, such as the Oyster travelcards, which could lead to the end of ticket booth and barrier jobs.
TUBE PAY RATES
Train driver: £32,656
Train inspector £34,075
Station assistants: £19,776
Station supervisor: £35,560
The RMT rejected an improved offer from LU managers on Monday, which would give workers a pay rise of 3.5% over the next year and a guarantee to reduce the working week by two-and-a-half hours by 2006.
It said there were unacceptable "strings" attached to the deal and fears 800 jobs could be lost. It is also fighting for a four-day week.
LU has condemned the strike as "completely unacceptable".
Managing director Tim O'Toole said: "I am sorry for the difficult journey many passengers are having to face.
"We are encouraged by the number of train drivers at work, which is allowing us to run more services than we expected and I would like to thank those staff who are keeping London moving."