Major freight railroads have agreed among themselves to adopt new safety measures, pledging to expand a network of sensors designed to catch overheating bearings and setting a common standard for when those sensors warn train crews to stop and look for danger.

The Association of American Railroads announced the steps Wednesday, saying the measures demonstrated the industry’s commitment to acting swiftly on safety as the National Transportation Safety Board continues to probe last month’s derailment and chemical spill in East Palestine, Ohio.

“Healthy railroads are essential to the U.S. economy, and consistently and reliably safe operations are essential to healthy railroads,” said Ian Jefferies, the association’s chief executive. “Our long history of voluntarily employing safety measures that go above and beyond federal requirements proves our belief in that principle.”

The measures were announced on the eve of the first congressional hearing on the East Palestine derailment and come as lawmakers and Transportation Secretary Pete Buttigieg push the industry to improve its safety record. Norfolk Southern, the operator of the derailed train, is under particular scrutiny, with the NTSB and the Federal Railroad Administration announcing reviews of the railroad’s safety practices Tuesday after one of its employee was killed in Cleveland and a train derailed Saturday in Springfield, Ohio.

The steps the industry announced Wednesday – which include aid for emergency responders to better manage derailments – tackle safety issues raised by the FRA and the Pipeline and Hazardous Materials Safety Administration in advisories last week.

The Association of American Railroads said freight lines would aim to install 1,000 new hotbox detectors on their networks, seeking to have the devices spaced, on average, 15 miles apart. Norfolk Southern said Monday that it would add 200 detectors. The devices measure the temperature of bearings on passing trains, sending a warning to crews if any are dangerously hot – a sign of an impending failure that can lead to a derailment.

The NTSB has said thresholds at which those warnings are issued vary among railroads. The association said the industry has agreed to a single standard, committing to stopping trains and inspecting bearings that read 170 degrees higher than the surrounding air.

Norfolk Southern already used that standard, but on the route into East Palestine there are two detectors 10 miles apart, followed by a gap of 20 miles. The first two recorded elevated temperatures, but not above the 170-degree threshold. By the time the train passed the third, the temperature had spiked to 253 degrees above the ambient temperature, triggering a warning that came too late for the crew to safely stop the train.

The NTSB has said the derailment might have been avoided if detectors had been closer.

Railroads analyze data from multiple detectors to identify trends – such as rising temperatures – to catch problems before they become critical. The railroad association said major freight railroads are reviewing how they conduct those analyses, aiming to issue recommendations by the end of the month.

While detectors have been credited with reducing derailments, they are not perfect. The FRA has highlighted an Oct. 8 incident involving a Norfolk Southern train in Sandusky, Ohio, in which a dispatcher alerted a train crew to a potential problem bearing. The train was stopped and an electrician investigated, finding that the bearing had cooled. The crew was then told to continue, but after seven miles the bearing failed and the train derailed, spilling molten paraffin wax.

Railroads also announced plans to provide training for 20,000 first responders this year across the country to better prepare them to handle such incidents. The industry also will expand efforts to sign up emergency responders for a data-sharing app that provides information on hazardous materials on trains, aiming to double the number of crews with access by the end of the year.

Norfolk Southern separately announced Wednesday that it would open a new regional training center for first responders in Ohio and expand a traveling training program. The railroad said it would begin training classes March 22 at a yard in Bellevue, Ohio, while it sought a permanent site for the new center.

As the industry takes voluntary steps, federal regulators and lawmakers are weighing whether to impose new rules on railroads.

On Thursday, Norfolk Southern chief executive Alan Shaw is scheduled to testify on the East Palestine derailment before the Senate Environment and Public Works Committee. Previewing the hearing on Wednesday, Sen. Thomas R. Carper, D-Del., the committee’s chairman, noted an opportunity to learn from the derailment.

“The key is for us to think and find out what went wrong, find out how it could be avoided in the future, what can we do better and make sure that we do that – and follow up on that, and that we don’t just get distracted by another issue next week or the next month,” Carper said.