Transport Canberra has apologised to a student and her family after the 17-year-old was forced to leave a light rail vehicle on Saturday evening over her failure to produce student identification.

Key points: The student left the light rail on Saturday evening when she failed to show ID

The student left the light rail on Saturday evening when she failed to show ID Transport Canberra apologised, calling it an 'unfortunate event'

Transport Canberra apologised, calling it an 'unfortunate event' They said vulnerable people should be allowed to stay aboard light rail vehicles

The girl was travelling on the light rail network at about 7:30pm when her MyWay pass was checked by a customer service officer.

According to Transport Canberra, she was told she could either get off the vehicle at the next stop and buy a full-price fare or pay a fine.

A witness, Darla, told ABC Radio Canberra the girl "pleaded" with staff to allow her to stay on the vehicle before disembarking at the next stop.

"She told them she couldn't afford a fine, and then they were pretty much like, 'too bad'," Darla said.

"I remember she said, 'do you want me to show you photos of me in my school uniform?'"

Darla made a complaint to Transport Canberra, who today apologised and said the incident should never have happened.

Executive group manager for Transport Canberra's public transport operations Judith Sturman said staff on the new light rail line were on a "learning curve" when it came to implementing MyWay pass policy.

"We've had long talks with Canberra Metro and we've both agreed that a common sense approach is that this is not the way we want to treat our passengers," Ms Sturman said.

"So that's absolutely our categorical position."

After the girl disembarked at Dickson, she boarded the next vehicle, where she again failed to produce the appropriate identification.

That time, however, she was allowed to stay onboard with a warning.

Ms Sturman said the correct approach was to issue a warning to any underage person without the correct pass or identification, and that it should have been the approach in the first instance.

"It was on a Saturday evening and older teenagers sometimes do look older than teenagers, however with all that in account, we still believe the correct thing to do would be to warn the female to remember next time to have their concession card with them," she said.

"We do accept that there are vulnerable people travelling, including children, on our network and — as we have a protocol with buses — we do not put children off buses.

"It's a learning curve."

The girl and her family have been contacted by Transport Canberra and Ms Sturman said they were satisfied with how the incident had been handled since Saturday.

"[In future] we will issue a warning and we will understand the person's situation so that we don't make a knee-jerk response, which I think is what happened in this instance," she said.