PITTSBURGH — The Norfolk Southern freight train that derailed in East Palestine, Ohio, on Feb. 3 had passed through three temperature sensors designed to alert problems like the hot bearing that eventually failed that day.
But the only sensor, called a hot box detector, that registered a sufficiently high temperature to sound the alarm was the one less than a mile from the accident site, according to preliminary findings from the National Transportation Safety Board, released Thursday.
Although at least two videos taken from security cameras in Salem, Ohio — 20 miles west of the derailment site — showed the train had one car that glowed from the bottom, the hot box detector at that site assessed the temperature of the fiery bearing on the rail car to be 103 degrees Fahrenheit above ambient temperature.
At a hot box detector 11 miles before that, the bearing registered as 38 degrees above ambient.
Norfolk Southern’s settings don’t activate alarms until the temperature reaches 170 degrees above ambient, or shows a difference of at least 115 degrees between the suspect bearing and another bearing on the same axle. That means that while the temperature in the bearing rose by 270% over the course of 11 miles, neither the crew nor the dispatcher would have been alerted to the trend.
By the time the train crossed the hot box detector in East Palestine, it clocked in at 253 degrees above ambient temperature, which triggered a critical alarm, alerting the crew to stop immediately and inspect the train, which they tried to do.
But it was too late.
The 150-car train, weighing 17,977 tons, stretching more than a mile and a half in length and traveling 47 miles per hour, had derailed at the 23rd. The troubled bearing had ground down and failed, according to the preliminary NTSB report. When the train stopped, the crew saw smoke and fire. The dispatcher authorized the crew to uncouple the lead locomotive and drive down the track for about a mile to a safe distance.
In total, 38 cars went off the tracks and the resulting fire damaged an additional 12. No one was injured but thousands were displaced from their homes before and for several days after a controlled burn of five tanker cars containing vinyl chloride sent an ominous dark cloud into the sky.
‘A crap shoot’
Constantine Tarawneh, who directs the University Transportation Center for Railway Safety at the University of Texas Rio Grande Valley, has been studying the efficacy of hot box detectors for two decades. Speaking before the NTSB report was released, he said he would not be surprised to find that the technology failed to detect the problem in time.
“Temperature is not a good metric to measure the condition of bearings or moving elements in general,” he said. “Meaning, by the time you detect something with temperature, it’s already too late.”
He said it’s like waiting for a raging fever to indicate sickness instead of relying on the sore throat and runny nose that precede it.
Some detectors underpredict the temperature by 80%, he said. Others trigger false alarms so frequently that railroads calibrate their response to those alerts.
“It’s kind of a crap shoot,” he said.
Over the past 20 years, overheated bearings have led to 416 derailments, according to Federal Railroad Administration data on train accidents. That’s an average of about two dozen a year, with the vast majority not nearly as impactful or catastrophic as what happened in East Palestine.
A review of those records shows that in situations where a hot box detector is mentioned, the alerted train crew stops the train to find cars already derailed on the tracks.
The Federal Railroad Administration does not regulate hot box detectors and so doesn’t require railroads to report data on how they perform. That makes it difficult to know how many avoided derailments can be attributed to hot box detectors.
In a report released in May, the agency studied the effectiveness of wayside detectors, concluding that their growth has “significantly helped in reducing the number of derailments related to freight car/components.”
The FRA study simply mapped the rise of wayside detection technologies, which also include devices that alert for dragging equipment or too much pressure on a wheel, against the rate of derailments among freight railroads. Hot box detectors were by far the most commonly-installed technology, with about 6,000 in operation across the U.S.
Specifically, the Federal Railroad Administration concluded these detectors most dramatically reduced derailments from overheated bearings.
“Effective detection of these defects has led the railroads and equipment owners to monitor their fleet and schedule maintenance and repair to correct these issues,” the study said.
But it also noted that the Association of American Railroads, the industry group that sets policies and standards for rail operators, is studying the issue with a “focus on developing a bearing temperature trending criterion for industry-wide acceptance.”
On Tuesday, the U.S. Secretary of Transportation Pete Buttigieg called on Norfolk Southern and all freight railroads to enact certain measures he thought would improve their safety performance. Those include accelerating the adoption of safer tank cars; supplementing, instead of abandoning human inspections with new technologies, like automated track inspections; paid sick leave for railroad workers; and letting states know when hazardous materials are traveling through their territories.
The Association of American Railroads suggested that policy changes should come after the NTSB’s work is done.
“All stakeholders — railroads along with federal, state and local officials — must work to restore the public’s trust in the safety and security of our communities. We can only do that by letting the facts drive the post-accident response.”
NTSB investigations can take months or even years before a final report is released.
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