Passengers on some of the country's busiest rail routes face disruption on New Year's Eve as workers stage a day of strike action in a long-running dispute over guards on trains.
Rail, Maritime and Transport Union (RMT) workers on South Western Railway (SWR) walked out at midnight.
The RMT claimed SWR will be "bailed out" by the government for revenue lost as a result of the strike action
The rail operator said it was running a reduced service across the network.
The 24-hour strike is affecting services across the south of England, including London Waterloo, the capital's busiest station.
Some rail replacement bus services are in place and SWR said it would "do everything we can to keep customers moving and reduce disruption".
"The RMT continues to play politics with their ongoing strike action, causing misery at a time when people just want to be with friends and family or get to work," it added.
The operator warned travellers to check its own website for amended services as some were not showing correctly on National Rail online journey planners.
Some travellers turned to social media to vent their frustrations.
The replacement buses into London tonight are gonna be so rowdy I actually feel sorry for the drivers #SWRStrike— M (@_nineclouds) December 31, 2018
Having been spared the pain of the #replacementbus last week (thanks to a very kind friend giving me a lift to and from work), I braved the #RMTStrike today on #SWR. Apparently a lot of people decided not to bother, so I had a seat. More than 2 trains a hour would've been nice.— Corrina (@penguin_of_doom) December 31, 2018
The RMT said its members were "united and determined" in taking industrial action.
General secretary Mick Cash said: "Official parliamentary answers have shown that the government is preparing to bail out South Western Railway for revenues lost as a result of strike action.
"Passengers will be outraged to know that instead of taking steps to resolve this dispute rail ministers are instead prolonging it by using tax payers' money to prop up South Western Railway on strike days."
SWR said "additional and amended services" would operate in the early hours of New Years Day with extra trains laid on for revellers travelling home from celebrations in the capital.
Which services are affected?
- Basingstoke to London Waterloo: Reduced service with one train an hour running in each direction
- Salisbury to London Waterloo: An hourly reduced service will run
- Guildford to Ascot: A bus service will be in operation
- Portsmouth to London Waterloo: Due to planned engineering works there will be a reduced service and rail replacement services between Woking, Guildford and Haslemere
- Portsmouth to Southampton: Trains will run between Southampton Central and Fareham, with one service every two hours
- London Waterloo to Reading: Two trains an hour will run between Clapham Junction and Reading
- London Waterloo to Weymouth: Hourly trains will run between Waterloo and Bournemouth, with a shuttle service between Bournemouth and Weymouth
- Salisbury to Romsey via Southampton: No services