The incident occurred at 12:45 p.m. Wednesday along the Market-Frankford Line at 56th Street.
Surveillance video obtained first by Action News shows a woman standing on a platform with her 14-month-old daughter in a jogging stroller.
The stroller slowly rolls toward the eastbound track and topples over with the child inside.
The stroller comes to rest on the rail. Luckily, the outer rail was not charged.
The video shows the child's mother jumping down into the well and lifts her baby to a man waiting on the platform.
Other passengers run over to help; one woman hits the call button to alert SEPTA police.
SEPTA System Safety Director Scott Sauer says he was shaken by what he saw on the video.
"It's heart-wrenching because you can anticipate it because the stroller does start to move at a very slow rate of speed and it kind of builds up. You want to tell someone to grab the stroller," Sauer said.
SEPTA police were able to stop an incoming train at 60th Street. No other trains passed during the incident.
"Our Market-Frankford Line is one of our busiest lines and our trains run quite often, every 6 to 10 minutes apart. In this case, the stroller went into the track area, fortunately when there were no trains running," Sauer said.
The 14-month-old suffered a laceration to the forehead.
Paramedics responded and transported the baby to Children's Hospital of Philadelphia for treatment.
SEPTA police have talked to the child's mother and say there will be no charges filed.
They say it was an accident and serves as a reminder for other SEPTA riders to lock the stroller brake when waiting on the platform.