Investigators told a federal safety panel Tuesday that the trolley operator who died after her train rammed another trolley in a May 2008 collision in Boston had apparently ignored a red stop signal.
The National Transportation Safety Board was meeting to analyze the accident in suburban Newton, Mass. that also injured seven passengers on the Massachusetts Bay Transportation Authority's Green Line.
The signal had been stuck in the stop position. The operator, Terrese Edmonds, 24, should have halted her trolley for one minute and continued slowly at 10 mph because the signal was red, indicating a train ahead, investigators found.
Instead, her trolley plowed into another train. Investigators estimated the striking trolley was moving at 38 mph at impact.
The trolley struck from behind had stopped at a second malfunctioning red signal.
Investigators found broken electrical connections between track sections, interrupting the signal that would have made the signal lights go on and off correctly.
Operators were not required to report faulty signals by the MBTA, a factor that likely contributed to the accident, investigators said.
"This could lead to a great safety risk," investigator Jeff Leaman told the panel.
The crash damage was estimated at $8.6 million by investigators. An estimated 185 to 200 passengers were on the two trains at the time of the crash.
Investigators also told the panel testing showed no illegal drugs or alcohol were detected in the operator's system when she died.
Testing showed the presence of Doxylamine, which is used in over-the-counter sleeping aids, in Edmonds' urine. Investigators did not say in their report submitted to the safety panel whether they believed that was a factor in the crash.
This program aired on July 14, 2009. The audio for this program is not available.