Wednesday, August 19, 2009

A Single Track to Disaster

In order to make the Red Line viable for federal funding, the Maryland Transit Administration (MTA) chose to single-track a one-mile tunnel under Cooks Lane in western Baltimore. MTA itself has made the case for why single-track lines compromise service, passenger capacity, future growth and operational and maintenance flexibility. Here’s what they left out: single-track tunnels are not as safe as double-track tunnels. Not by a long shot.

The above picture shows what happened in Chatsworth, California, a Los Angeles suburb, about one year ago. According to the Associated Press, a freight train collided with a passenger train near a single-track tunnel. The passenger train was supposed to wait near a siding outside the tunnel but did not. The collision occurred close to the tunnel entrance.

Wikipedia provides the following account:

The 2008 Chatsworth train collision occurred at 16:22 PDT (23:22 UTC) on Friday September 12, 2008, when a Union Pacific freight train and a Metrolink commuter train collided head-on in the Chatsworth district of Los Angeles, California, in the United States. The scene of the accident was a curved section of single track on the Metrolink Ventura County Line just east of Stoney Point.

Before the collision, the Metrolink train may have run through a red signal before entering a section of single track where the opposing freight train had been given the right of way by the train dispatcher. The Metrolink train’s engineer was near the end of a work week of long split shifts, making fatigue a subject of the investigation, along with distraction from text messages he was sending while on duty. The accident remains under investigation; meanwhile the basic circumstances have been released to the public, but the official report determining probable cause is expected to take up to a year to complete.

This mass casualty event brought a massive emergency response by both the city and county of Los Angeles, but the nature and extent of physical trauma taxed the available resources. With 25 deaths, this became the deadliest accident in Metrolink’s history. Many survivors remained hospitalized for an extended period. Lawyers quickly began filing claims against Metrolink, and in total, they are expected to exceed a US$200 million liability limit set in 1997, portending the first legal challenges to that law. Issues surrounding this accident have also initiated and reinvigorated public debate on a range of topics including public relations, safety, and emergency management, which has also resulted in regulatory and legislative actions.
USA Today reported that the collision was the deadliest in the United States since an Amtrak crash in 1993. The newspaper said this about the accident:

The collision occurred on a bend in the track just before a tunnel along the Metrolink track in the Chatsworth section of Los Angeles' San Fernando Valley.

The line consists of only a single track heading into the narrow tunnel in a residential area.

“Thank God it (the crash) wasn’t in the tunnel — there’d be a lot more killed,” said Lt. Cheryl MacWillie, watch commander for the coroner’s office.
Chatsworth is far from the only single-track tunnel disaster in recent times. In January 2003, a French passenger train collided with an Italian passenger train in a single-track tunnel near the two countries’ border. Two Italians died. In June 2000, two trains collided at the entrance to a single-track tunnel in Zugspitze, Germany. Fifty-seven people were injured, including one man who “was flown to a hospital by helicopter after rescue workers freed his crushed legs from the wreckage.” In August 1993, twelve people were killed when a passenger train collided with a goods train in a tunnel near Vega de Anzo, Spain. Many more crashes have occurred on single-track lines not involving tunnels, including at Pecrot, Belgium (2001); Glasgow, Scotland (1989); Dahlerau, Germany (1971); Violet Town, Australia (1969); and countless others in decades before.

In March 2003, Terje Andersen and Borre Paaske published a study comparing the safety records of single tunnels to double tunnels for international risk manager DNV Consulting. They were specifically interested in smoke levels from fires. Below is their finding for smoke levels in a double tunnel, with red marking the highest smoke levels and blue marking the lowest levels:

Below is their finding for smoke levels in a single tunnel, with red marking the highest smoke levels and blue marking the lowest levels:

When Andersen and Paaske compare the fatality risk of single and double tunnels, single tunnels FAR surpass double tunnels in all scenarios. For the longest tunnels (much longer than the one planned in Baltimore), single tunnels actually have a higher fatality risk than passenger cars.

All of the above information is easily available to transportation planners and railway engineers, not to mention the general public. The Maryland Transit Administration either knew or should have known of the dangers associated with single-track tunnels at the time they proposed one for the Red Line. If they actually construct a single-track tunnel in Baltimore, they risk a disaster that could surpass Chatsworth or WMATA and join the ranks of the deadliest rail accidents in American history.

Is it worth it?