(AP) — Freight railroads should reexamine the way they use and maintain the detectors along the tracks that are supposed to spot overheating bearings, federal regulators urged Tuesday in the wake of a fiery Ohio derailment and other recent crashes.

The safety advisory from the Federal Railroad Administration stopped short of telling the railroads exactly what to do. Instead, it encourages them to make sure the detectors are getting inspected often enough by trained employees and that the railroads have safe standards for determining when to stop a train or park a railcar when a warning is triggered.

The National Transportation Safety Board has said the crew operating the Norfolk Southern train that derailed outside East Palestine, Ohio, near the Pennsylvania border on Feb. 3 got a warning from such a detector but couldn’t stop the train before more than three dozen cars came off the tracks and caught fire. The Federal Railroad Administration said overheating bearings likely caused at least four other derailments since 2021.

The Ohio derailment forced half the town of about 4,000 people to evacuate for days as toxic chemicals burned and created lingering health concerns for residents. Government tests haven’t found dangerous levels of chemicals in the air or water in the area.

“For trains containing hazardous materials, the potential consequence of a derailment is catastrophic, and allowing a train transporting a hazardous material to continue to operate, without restriction, after an HBD (hot bearing detector) alert is likely not appropriate,” the FRA said in its advisory.

Norfolk Southern officials didn’t immediately respond to the advisory. After the NTSB issued its preliminary findings last week, the railroad said that the derailment had prompted it to inspect all of the nearly 1,000 trackside heat detectors on its network. That was on top of the regular inspections it normally does on those sensors every 30 days, Norfolk Southern said.

Dave Clarke, the former director of the Center for Transportation Research at the University of Tennessee, said the safety advisory was not surprising.

“This is just FRA proposing the obvious, in my opinion. I doubt if any Class I (major freight railroad) was waiting for this,” he said.

The Association of American Railroads trade group said the industry has a strong track record of pushing for safety improvements to prevent derailments and tough tank car standards to prevent hazardous materials spills. The group said the widespread use of these detectors is an example of the industry’s commitment to safety because they aren’t required under federal rules.

“As we continue to learn more about the cause of the accident in East Palestine, the industry is reviewing its practices and procedures to determine next steps to further enhance safety and target the root cause of this accident,” the group said in a statement.

Professor Allan Zarembski, who leads the University of Delaware’s rail engineering and safety program, said regulators should make sure any new rules don’t lead to a big increase in false alarms that will “stop trains right-left across the entire network.”

Overheating bearings cause only a handful of the more than 1,000 derailments each year, indicating that the existing system already finds nearly all such problems, he said.

“There’s great political pressure to do something now — knee-jerk reaction, `Do something now. We’ve got to do something now.’ But I’m not convinced the knee-jerk reaction is going to do a lot of good,” Zarembski said.

Transportation Secretary Pete Buttigieg proposed a number of safety improvements last week, but the industry has been pushing to delay any major changes until after the NTSB completes its investigation a year or more from now.