SEPTA will inspect automatic train-control signals on the Market-Frankford Line made by the same company that made the signals on the Metro in Washington, where a possible signal malfunction is under investigation in Monday's deadly train collision.

The electronic signal circuits along the tracks tell passing trains when to stop or slow down.

The signals on the Market-Frankford Line, like those in Washington and many other U.S. cities, were made by Alstom S.A., a large French manufacturer of transportation equipment and power plants.

National Transportation Safety Board investigators in Washington are focusing on the signal circuits in a 740-foot stretch where the collision killed nine people and injured about 80. Testers found "anomalies" with those circuits, NTSB officials said.

"Whether trains are operated in automatic or manual, these circuits are vital," said Debbie Hersman of the NTSB. "We're particularly interested in the speed commands that might be sent from that circuit when there's a train standing on that circuit."

In Philadelphia, crews will inspect all the circuits on the 13-mile Market-Frankford Line, said Michael J. Monastero, SEPTA's assistant chief engineer for communications and signals. There are about 50 signal circuits on the Blue Line, he said.

The circuits are inspected monthly, quarterly, and annually, Monastero said, "and we've had no problem with those."

But the Washington crash and reports of problems in Boston with Alstom circuits prompted SEPTA to "go to DEFCON 3" and order an immediate inspection, he said.

The control signals on the agency's other subway, trolley, and rail lines operate differently and were not made by Alstom, Monastero said. They, too, are inspected regularly, he said.

SEPTA's Market-Frankford signals are probably a generation newer than the Washington signals, Monastero said. He said the Blue Line equipment was similar to that used in San Francisco's Bay Area Rapid Transit system.

Monastero will confer in Boston next week with engineers at the Massachusetts Bay Transportation Authority about their Alstom signals.

Last month, the equipment did not detect trains along one section of Boston's Orange Line. Engineers discovered the problem and immediately stopped using the automated system while they checked all circuits. Trains were dispatched by radio for 12 days, and MBTA personnel were posted at each station to give the go-ahead for trains to proceed, an MBTA spokesman told the Washington Post.

Monastero said SEPTA and other transit agencies were scrambling to make sure automated signal systems are operating properly, without knowing exactly what went wrong in Washington.

"Once we see the NTSB report, or even a draft, we'll know better what happened there," he said.

Such a report is months away.

Contact staff writer Paul Nussbaum at 215-854-4587 or pnussbaum@phillynews.com.
This article contains information from the Associated Press.