A man has described the terrifying moment he helped rescue a young girl perched precariously on a railway bridge threatening to jump in front a train.

Grady O'Neill was walking to Chatham station on his way home from work on Monday evening when he says he saw a teenager on the other side of the road.

The 19-year-old apprentice electrician from Strood saw her on the top of the wall before "swinging her legs around" to face the tracks.

Initially he thought she wanted to jump down to avoid paying a ticket but says when he realised something could have been wrong he raced to try to help.

Grady says he went over to talk her down while getting close enough to grab her if she did jump or fall.

A police spokesman confirmed officers were called at 5.15pm to reports of concern for the welfare of a person in Railway Street.

"I was shocked so got closer and thought she was going to jump," Grady said.

"It was pretty scary. I just hope that she's OK..."

"When I saw her out of the corner of my eye I didn't know what she was doing but when I did clock it, I knew I had to get there as soon as possible."

"I was trying not to make any sudden movements as the train got closer."

Drivers passing saw Grady and the girl and pulled over to see how they could help and started getting out of their cars.

He added: "Another bloke, fair play to him, came around behind me and we were talking but she wasn't listening to anyone.

"I helped him get her to the floor and calm her but she was screaming."

Station staff called police who arrived to help look after the girl and she was taken inside the station.

"It was quite lucky but I was really shocked and didn't really know what she was doing."

Grady, who works at Jascom Electrical Contractors Limited, says the whole incident lasted between 30 seconds to a minute but said "that's a long time when someone is sitting on a ledge".

"It was pretty scary and I was a bit shaken up after it all happened," he added. "I just hope that she's OK.

"Credit to the other guy, he did the right thing in getting her away from the danger point."

Station manager Amanjeet Malait said: “We’re very proud of our two welfare officers who were able to intervene so quickly in this instance and get this young woman the care she needed.”

The police spokesman added: "The girl was taken to hospital as a precaution and passed into the care of medical professionals."