Updated

Philadelphia transit officials say an old-fashioned but vital piece of safety equipment helped avert disaster when a stroller carrying an infant fell onto train tracks.

An alert passenger at a west Philadelphia station used a call box to notify the Southeastern Pennsylvania Transportation Authority about the emergency Wednesday afternoon.

Gale Walker took the call at SEPTA police headquarters and said Thursday she was stunned by the report. She immediately told dispatchers to hold the eastbound Market-Frankford Line.

Surveillance video shows the stroller rolling off the slanted platform and falling a few feet to the tracks below. As the infant's mother jumps down to save her, a bystander uses the call box speakerphone.

SEPTA officials say call boxes are used infrequently because most people use their cellphones to report emergencies.