SEPTA authorities released video of the incident, which happened Tuesday at the Ellsworth Federal Station in South Philadelphia.
In the video you can see the woman walking near the edge of the platform. Then all of sudden, she plummets onto the third rail, which was pulsing with electricity.
Witnesses rushed to get help.
Emergency personnel arrived and freed the woman. She was then loaded onto a stretcher and taken to the hospital.
Officials say the woman is lucky to be alive.
SEPTA Transit Police Capt. Thomas Nestle says, "I can tell you that not too many people live after coming in contact with the third rail. That is down there to run a major train operation and it's certainly not meant to be touched by a human body. She's lucky."
Authorities are not commenting on the woman's condition. It is still not clear why she fell in the first place.