Port Authority is inspecting its entire fleet of light-rail vehicles after determining that a broken connector on a piece of safety equipment caused a derailment near Bethel Park last month.

An investigation of the Aug. 4 incident showed that a safety board — a Fiberglas bar mounted in front of the wheels and intended to knock away obstacles or debris on the track — came loose and started dragging under the train as it traveled south from the Washington Junction station, said Winston Simmonds, the agency's rail operations officer.

The dragging board got caught in the switch where the track splits into the South Hills Village and Library lines. It broke off and fell under the wheels, causing them to come off the rails.

None of the 60 passengers was injured.

Simmonds said the fasteners connecting the safety board near the wheels failed. An inspection of the rest of Port Authority's 83-vehicle train fleet found loose or missing fasteners on 12 other vehicles and missing "safety wires," which wrap around the fasteners, on two others.

"We believe it's a design problem," Simmonds said. "Those housings get a lot of vibration. We're trying to determine if the fasteners are working themselves loose."

Port Authority contacted Madrid-based train manufacturer CAF to work on the problem. The "trucks" that hold sets of wheels on all of Port Authority's light-rail vehicles use the same design after Siemens trains purchased in the 1980s were rebuilt to use the same parts as the CAF trains bought in the late 1990s.

Officials from CAF could not be reached for comment.

The transit agency will review the trucks with CAF to determine whether the problem is with how they're designed, or whether the vibrations are being caused by heavy loads on the trains, Simmonds said. An examination might include placing instruments on the trucks of a rail car to measure the vibration, or replacing the lightweight cast-aluminum housing the board was connected to with heavier, sturdier steel.

Marks on the tracks and ties indicated the train dragged the safety board about 2,000 feet. The train operator was unable to hear it because the board was on the trailing car of a two-car train, Simmonds said.

Workers at the South Hills Village maintenance facility are being directed to pay close attention to the fasteners during weekly inspections of each vehicle. The vehicles with the loose or missing bolts were repaired and returned to service, Simmonds said.

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