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NTSB: Green Line crash could have been prevented

E-mail|Link|Comments () July 14, 2009 12:20 PM

National Transportation Safety Board

By Noah Bierman, Globe Staff

Investigators for the National Transportation Safety Board said today that a fatal Green Line crash in May 2008 could have been prevented if the MBTA had an automated train control system.

That finding was the unanimous conclusion of a public hearing today in Washington, D.C., where the board discussed the investigation of the rush-hour crash May 28, 2008, that killed MBTA operator Ter’rese Edmonds. Acting NTSB Chairman Mark V. Rosenker said that installing an automated or positive train control system on the Green Line would be "worth it if we can prevent accidents and loss of life and injuries."

"If technology exists and it exists on the other [MBTA] lines, why would the Green Line not have everything possible that is going to prevent the accidents from happening?" Rosenker asked. "I don’t understand that as an operator. I just don’t if the technology exists.”

MBTA General Manager Daniel A. Grabauskas has previously said it would be difficult to install an automated train control system on the antiquated Green Line because of the high volume of trolleys running through underground tunnels. During today's NTSB hearing, however, officials said technology existed to retrofit the Green Line with a failsafe computer system to control the trains and help prevent collisions.

In recent months, the MBTA has begun testing such automated systems, which are far from perfect. For example, the automated train control system on the Metro in Washington, D.C., did not prevent a crash last month that killed nine people.

During today's hearing, board member Robert L. Sumwalt said he was "fairly incredulous" that prior to the crash, the MBTA did not have a formal system to check whether train operators were obeying signals and following other safety rules.

“I think it speaks to the lack of a safety culture of the organization that they did not do those things,” Sumwalt said.

Investigators also determined that Edmonds was at high risk for undiagnosed sleep apnea and may have dozed off or experienced a “micro-sleep," preventing her from pressing the brakes in the seven seconds when she could have seen a trolley stopped ahead of her. Board members said today that the MBTA lacked employee screening for sleep apnea and had an inadequate fatigue awareness program.

The accident also demonstrated the need to implement minimum construction standards of rail cars to ensure crash worthiness, according to board member of Debbie Hersman.

The Globe reported today that dozens of pages of investigative documents were released on Monday by the board. While no officials would detail a cause, documents and prior statements from investigators suggest that a driving error by Edmonds was the primary reason for the crash.

In testimony released this week, Linda Jenness was working in the rear of a Green Line train last year, slowly accelerating from a red light in Newton, when she “heard a horrific crash and felt my train being thrown.’’

“I just felt like an airplane hit me,’’ Jenness told federal investigators.

“It threw me out of the seat at first, but then I landed in the seat, and then I jumped up, and I hit my mushroom, which is the emergency brake, three times,’’ Jenness said. “It wasn’t stopping.’’

Jenness’s train had been stopped at what investigators believe was a signal that was stuck on red just west of the Waban station. The train had just started moving at the time of the crash.

The driver of the train, seated in the front car, had reacted to the red signal properly, stopping for a minute and then moving forward at no more than 10 miles per hour.

Tests later showed connections on the track that conduct electricity were rusted, which probably caused the signal to default to the red position, according to the report.

The report said the train behind, driven by Edmonds, 24, encountered a second red signal, requiring it to stop so it would not hit Jenness’s train. But Edmonds did not stop, according to crash records. She proceeded through the signal at 38 miles per hour, causing the violent rear-end collision that fatally injured Edmonds.

It remains unclear why Edmonds ignored her red signal. The records released yesterday say there were no illegal drugs or alcohol found in her system when she died. There was, however, the presence of Doxylamine, often included in over-the-counter sleep aids, in Edmonds’s urine.

Investigators did not say in the initial report whether they believed that was a factor. The drug, found in medicines such as Unisom and some versions of NyQuil, can leave people sluggish even a day after taking it, said Candy Tsourounis, professor of clinical pharmacy at the University of California at San Francisco.

“With most over-the-counter medicines, you will see some drowsiness eight, 10, 12 hours after the dose.’’ Tsourounis said.

Drugs containing the product customarily include a warning about operating heavy machinery.
The crash that killed Edmonds also injured seven other passengers, one of them critically.

Damage to the trolley cars involved in the crash was estimated at $8.6 million.

The NTSB is also investigating a second Green Line rear-end crash near Government Center that occurred May 8 this year. In that crash, an operator told authorities he was writing a text message to his girlfriend in the moments before impact.

Though both crashes seem to be the result of operator error, the MBTA’s antiquated signal system has been criticized for its lack of an automated crash-prevention system. The NTSB is expected to discuss that issue in its report today.

Other lines and other systems across the country have automated systems designed to prevent trains from coming too close to one another.