The person apparently electrocuted Friday morning atop a SEPTA Regional Rail car suffered injuries that are making identification difficult, police reported.
Investigators believe the person was a male, between 16 and 20 years old, but he suffered severe burns on his face and body, and his clothes and belongings were also badly burned, police said.
He was found at the rear of the top of the train near power lines when the Fox Chase line train pulled into Jefferson Station in Center City at 7:49 a.m., police reported.
It is not yet known how the male got on top of the train or whether the death involved the deadly activity known as train surfing. SEPTA officials said they were waiting for the results of the investigation by the Philadelphia Police Department.
The National Transportation Safety Board said Friday it would not open an investigation into the death.
Regional Rail trains run on almost 12,000 volts of electricity channeled from overhead catenary, or wires, to the train by a connector called a pantograph. Both SEPTA trains and trolleys use pantographs to link cars to wires, though the voltage on trolleys is less powerful, said Scott Sauer, SEPTA's assistant general manager for operations.
"Both voltages could kill you instantaneously if you're exposed to it," he said.
A person wouldn't even need to touch either the pantograph or the catenary to be killed, he said. Someone carrying metal, like a set of keys, runs the risk of causing the voltage to arc into them.
SEPTA's trains all have warnings of the electrical current, and SEPTA employees must go through
specific protocols to ensure there is no electricity in catenary or pantographs before getting on top of a train.
There have been reports over the years of people being electrocuted while riding on top of electrified trains, including two 21-year-old men who were killed while riding on a NJ Transit train in 1984. In 2010, an 11-year-old died at SEPTA's Wayne Electric Shop after he climbed onto a parked train and touched an electrified mechanism.
"It's certainly not common," Sauer said. "It doesn't happen a lot, and when it does it does not turn out well for the person involved."
At least two deaths were attributed to train surfing on New York subways last year. Getting on top of a subway car carries different risks, Sauer said, because those trains are electrified through the rails, not overhead wires.
"Even if there's no electrical exposure on top of a subway car," he said, "there's no room between you and that tunnel on top of a subway train."
This story has been corrected to change the voltage SEPTA trains run on.