CHICAGO (CBS) — An Amtrak train making its first-ever run along newly upgraded track derailed Monday on an overpass in Washington state.

The train derailed where the track curved onto the bridge across Interstate 5. While it’s too early to know exactly what went wrong, CBS 2’s Jim Williams looks at the concerns surrounding rail safety.

Joe Schwieterman, a DePaul professor and transportation expert, says sharp curves alone would not explain why the train detailed.

“These kinds of accidents are really rare, and usually it’s a multitude of factors that come together to make something this horrible happen,” he said.

Investigators plan to: Test the train engineer for drugs and alcohol; examine the condition of the train and the tracks; look at the train’s black box; and watch video from cameras in back of the train and up front near the engineer.

“To see what he saw and whether he reacted to it or how fast he reacted to it,” said Peter Greenberg, CBS News Travel Editor.

The crash will undoubtedly renew calls for Positive Train Control (PTC), a system designed to automatically stop a train that is going too fast before certain accidents occur.

Deborah Hersman, former chair of the National Transportation Safety Board (NTSB), spoke to CBS 2 Monday evening and called the accident a “worst case scenario.”

“We recommended this technology [PTC] because we know human beings make mistakes and we want to protect against those.”

PTC was not used on the Amtrak train that derailed Monday morning. It was supposed to be in place across the country two years ago, but the deadline was pushed back.

“It’s enormously complicated,” Schwieterman said. “That’s been too big of a bone for the railroads to swallow all at once.”

The line between Seattle and Portland was rebuilt for a passenger train. Though Monday’s was the inaugural trip, there had been test runs earlier this year. The new corridor was supposed to make the trip faster and more reliable.

RELATED: Following the accident, the Illinois Department of Transportation is stressing the steps it’s taken to maximize safety along the upcoming high-speed rail line between Chicago and St. Louis.