DENVER (KDVR) — Federal investigators have released preliminary information showing a broken rail likely caused the Colorado train derailment near Pueblo on Sunday.

That derailment killed a truck driver on Interstate 25 and has led to an indefinite closure of the interstate. The National Transportation Safety Board released its preliminary findings on Tuesday.

Train derailment investigator Gary Wolf told FOX31 that broken rails are a common cause of derailments.

“The rails are made of high-quality steel, but occasionally, there can be an imperfection in the rail,” Wolf said. “These can develop quickly or sometimes they develop slowly, and when they do, they start cracking out the railroad. And eventually, it results in the rail breaking part, and obviously, you lose continuity in the rail surface and the wheels go down and hit the ground.”

Wolf said railway companies use special equipment to test for broken rails multiple times each year, but he said defects can be tough to find.

“It’s very difficult to find these defects in a rail,” he said. “It’s the proverbial needle in a haystack that you’re looking for. When you’re going down the track with this ultrasonic test car, you’re looking for defects in the millimeter range, and they’re tough to find.”

Who’s responsible for maintaining the bridge?

Railroad companies typically own the bridges that trains use. However, BNSF said the steel girder bridge that collapsed onto I-25 was owned by the state.

Late Tuesday night, BNSF released a statement claiming they inspected the rail the very day of the derailment:

BNSF’s vision is to operate free of accidents and injuries, and every day we work to make that vision a reality through safety programs, training and technology. Our teams regularly conduct extensive track, bridge, rail and weather event inspections across our network. We meet or exceed all federal inspection requirements. We use a combination of instrumental rail cars and trucks, bridge inspection vehicles, unmanned aerial vehicles (UAVs) and specially trained inspectors. Specific to this area, 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 operates a very safe railroad but is committed to continuous improvement and will carefully consider the NTSB’s final report and recommendations when it comes out to more fully understand what lessons can be learned from this incident. 

Lena Kent, BNSF general director, public affairs

According to spokesperson Matt Inzeo, CDOT is “aware of the statements BNSF has been making regarding ownership,” saying the agency is working through “every document we can find that deals with rules, responsibilities and ownership. One reason this is taking time is that we continue to encounter and need to resolve potentially conflicting information.”

Inzeo added: “While there are a handful of exceptions, the state does not own the railroad bridges that cross state roads. For all bridges owned by other entities, they have their own inspection and maintenance responsibilities as part of using that bridge for its given purpose (railroads and utilities are the most common cases of this). And for the few railroad bridges that the state does own, railroads also conduct their own inspections. We do not have records of BNSF’s inspections of this bridge.”