Thousands of commuters suffered delays today after a series of problems hit the transport network in London, while train passengers were warned of continuing disruption to services because of another strike by drivers.
The entire Docklands Light Railway system in the capital was suspended because of a "communications failure", while a signalling problem caused disruption at London's busy Liverpool Street station, where four platforms were unable to be used.
Journey times were extended by up to 20 minutes into and out of the station, one of the busiest in the country.
Over-running engineering works caused disruption to London Overground services, which were delayed by up to 25 minutes.
Meanwhile, East Midlands Trains said a second strike by members of the drivers' union Aslef tomorrow in a row over pensions will lead to a revised timetable, including replacement buses, following similar disruption yesterday.
Operations director Ian Smith said: "We delivered a good service for our passengers on May 1 despite the Aslef industrial action, and managed to run even more services than we had previously advertised.
"In total, we ran over 100 train services and more than 200 replacement bus services, and we are committed to providing at least the same level of service on the second day of industrial action.
"We would advise passengers to check before travel. We have been in regular contact with Aslef since they called this action, and have not been made aware of any plans they have to call off the industrial action.
"Aslef's position is difficult to understand and many of our employees are pleased that their pension contributions will reduce from July this year. The fact is that our drivers will save around £500 per year with no impact whatsoever on their pension benefits."
Aslef, which has 450 members at the Stagecoach-run company, is opposed to planned reductions in pension scheme contributions during the current "turbulent" economic climate.
Further stoppages are planned on May 8, 10, 15 and 17.