DENVER (KDVR) — A section of railroad track now at the center of a federal investigation was inspected just hours before a train derailed in Colorado on Sunday, according to BNSF Railway.

The derailment is under investigation by the National Transportation Safety Board.

A BNSF statement claims: “BNSF conducted a combination of rail detection testing, advanced track infrastructure testing and visual inspections within the last three months, including the most recent inspection that occurred on Sunday, October 15 prior to the derailment.”

BNSF has not responded to questions regarding what specific inspections happened on Sunday.

How railroad inspections work

Train inspector Gus Ubaldi, who now works for Robson Forensic, said most tracks nationwide are inspected at least once a week, depending on how busy the route is and whether passenger cars are involved.

He said those inspections usually involve something called a “high rail truck,” which allows an inspector to drive up and down the tracks.

“It’s a regular pickup truck,” Ubaldi said. “It’s got retractable wheels that allow me to put it on a railroad track and drive down the railroad track, and while you’re doing that, you’re looking for defects.”

Workers toil to clear cars that derailed in an accident over Interstate 25 northbound north of Pueblo, Colo.
Workers toil to clear cars that derailed in an accident over Interstate 25 northbound, Monday, Oct. 16, 2023, north of Pueblo, Colo. (AP Photo/David Zalubowski)

Ubaldi said those defects can be tough to spot, which is why rail companies also do internal inspections a few times a year.

“It’s like sonar,” he said. “If there are no defects in the rail, you will get a particular signal back. If there are defects, the signal is interrupted, and that tells you there is something there.”

Ubaldi said it’s nearly impossible to place blame until the NTSB can establish exactly where the rail broke, when it happened and why.

“Without knowing why it broke,” he said, “it’s all speculation to say, ‘Well, could they have noticed it or not?'”