Passengers have told how they got out of trains stuck for hours on South West Trains services outside London and walked down the tracks.
Services were halted near Woking, Surrey, on Thursday night following a signalling problem caused by a possible attempted theft of cable.
A group of passengers, including a heavily pregnant woman, said they were challenged by police at the exit.
South West Trains has apologised for a string of disruptions this week.
Network Rail said 60 trains out of London Waterloo were affected by the signalling fault.
It said further delays were caused when passengers went on the track, meaning power to the rails had to be turned off.
Emma Firth, from Farnham, who is eight months pregnant, was among the passengers who got off their train.
"Me and another man talked to each other and said: 'This is our only chance,'" she said.
"In my condition I wasn't going to sleep overnight on a train, I had no food or drink.
"So the man gave me a piggy back off the train and helped me walk down the track.
"One guard, with a torch, helped us walk across the track safely and was very polite but the police at the gates were very angry, saying we had trespassed.
"I got home around 2300 BST. I will not be using the train tomorrow, it will be a nightmare after this. I shall be working from home."
Another passenger, who asked only to be named as Keith, said he took the 18.33 South West Trains service from Clapham, which ground to a halt near Woking.
He said the passengers, who also included a diabetic man who need insulin, decided to get off the train after about two hours.
"There were constant announcements every five minutes from the train driver saying he did not know when we would be moving.
"There was about five of us and we decided to get off. We prised the door open and jumped.
"When we got to the gates the police tried to get our names, saying we were trespassing and that South West Trains take this behaviour very seriously.
"They didn't manage to get any of our names in the end. I got home at around 23.30."
A passenger on another train, James Bilderbeck, 39, from Basingstoke, told BBC News that the service he was on was stuck for more than four hours.
"It's a really miserable environment, stuck going nowhere. It's a distressing situation for all."
The company director described it as the worst delay he had ever known as a commuter.
Speaking at about 2330 BST, he said his train had finally got moving again and that he hoped to reach Basingstoke soon.
But he said that some passengers whose final destination was Weymouth could expect for their journeys to take up to seven hours.
MP for Mole Valley, Sir Paul Beresford, said: "It seems to me as though there was lack of communication between Network Rail and South West Trains, particularly as evacuation has to be done really carefully.
"Someone should have been telling the drivers and the drivers should have been telling people.
"OK, it doesn't make them move any faster but at least it gives them an understanding of what is going wrong."
A South West Trains spokesman apologised for the disruption, which was the latest in a series to hit passengers this week.
"A major signalling problem in the Weybridge area on Monday resulted in severe disruption," he said.
"A fatality at Mortlake, a line closure due to a damaged bridge and an ill passenger on a train at Earlsfield on Thursday morning resulted in many delays, cancellations and diversions.
"On Thursday evening, further signalling problems in the Waterloo and Woking areas resulted in a significant amount of delays.
"Working with Network Rail, we have endeavoured to minimise the impact of these problems, although this is of little consolation if you have been affected by one or more of these events."
Services were running to schedule on Friday morning, but with a reduced number of carriages.