A woman has been pulled to safety after fainting and falling on to railway tracks in Upper Hutt.

The woman was standing at the Upper Hutt platform just before 8am yesterday when she fainted and fell onto the tracks, Metlink said in a statement.

"A bystander immediately jumped on to the rail corridor and moved the woman off the tracks," Metlink said.

The Wairarapa service was approaching at the time, but was not going particularly fast. It was able to come to a stop about 20m before where the woman had fallen.

Rescuers helped the woman back onto the platform, where she was given first aid and attended to by paramedics.

Metlink said it was great that customers on the platform moved the woman to safety, but they generally encouraged passengers to notify staff if there was somebody on the tracks.

"With 53,000 passenger journeys on Wellington trains each day, medical emergencies are a regular occurrence on the rail network. Our staff are trained in first aid and deal with these situations as best they can, but fellow passengers are often the first on the scene," Metlink said.

"It was great that the customers on the platform assisted in moving this customer to safety, although generally we ask customers to escalate any trespass situation to our staff and stay out of the rail corridor.

"For their safety we suggest that customers stand behind the yellow line on the platform to keep a safe distance from the edge."

Metlink wanted to thank the people who rescued the woman, but don't know their contact details. They are asking them to contact the call centre on 0800 801 700.