A passengerless SEPTA regional rail train was halted dead in its tracks this week when one of its steel wheels split in half.
The unusual accident crippled the 14-year-old train as it traveled to the transit agency's newest station in Chester County. Neither the train operator nor the conductor was hurt.
"It was a stress crack that began from the inside of the wheel," said Tom Dorricott, an official with the Brotherhood of Locomotive Engineers.
He added that a broken wheel could have caused a catastrophic derailment.
"It's a testament to the equipment that this train did not fall from the track," Dorricott said.
The wheel snapped on SEPTA's R5 line as the train headed to the Thorndale Station, which opened Nov. 22.
The R5 line, from Doylestown in Bucks County to Paoli in Chester County, is one SEPTA's busiest regional rail lines.
The wheel trouble caused rush-hour delays, forcing some rail commuters onto shuttle buses.
The accident also triggered an emergency inspection of eight other Bombardier train cars at the Frazier yard, where the train with the snapped wheel was stored just before the mishap.
No other cracks or fractures were found in the wheels of those cars.
It was only the second time in more than 12 years that a train wheel snapped in two, SEPTA and the railroad union agreed.
Patrick Nowakowski, SEPTA's chief operating officer, said the train was put into service in 1986. A metallurgical test is being conducted to determine what caused the wheel fracture, he said.
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