How do 2 trains end up on the same track?

How do 2 trains end up on the same track?

Following Tuesday's train collision, the Early Show's Angie Winn contacted a former chairman of the National Transportation Safety Board, the agency expected to begin an investigation as early as Wednesday, to gain insight on how these incidents are possible. The video above contains her complete phone interview with Jim Hall.

AMARILLO, TX (KFDA) - A fiery collision between two trains -- 3 crew members still missing, and a fourth who is hospitalized after jumping from the car shortly before impact.

Throughout Tuesday, families and communities waited for answers. I reached out to Jim Hall, who is a former chairman for the National Transportation Safety Board and a leading expert on transportation security. I couldn't help but ask the question that looms in many minds: How do 2 trains end up on the same track?

"Regrettably they're more common than necessary because for almost 40 years the National Transportation Safety Board has been recommending that major railroads put in the system of "Positive Train Control" that would stop the trains from colliding in a situation like this," Hall said.

Hall said most major railroads have central computer control systems. However, many times those controls are still manually operated. When incidents like that one that took place Tuesday happen, Hall said there's a potential for computer error. There's also potential for human error.

Finding if either are responsible is what current NTSB leaders will begin investigating once the smoke has finally cleared. As of Tuesday evening, Department of Public Safety troopers classified the train crash blaze as 'smoldering,' and expect rescue operations for those missing to continue.

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