In wake of East Palestine toxic derailment, railroads focus on hot bearing detection (video)

CLEVELAND, Ohio – As the National Transportation Safety Board investigates an overheated bearing as the likely cause of the catastrophic derailment of a Norfolk Southern train in East Palestine, the railroad industry is taking steps to prevent such a disaster from happening again.

Norfolk Southern said last week that it will add more hot bearing detectors along its rail lines and reevaluate the temperature threshold that triggers a warning for a crew to stop a train and conduct an inspection.

The Association of American Railroads followed two days later by announcing an industry "drive toward a future with zero incidents and zero injuries – one where what happened in East Palestine never happens again."

The pledges follow a flurry of criticism leveled against Norfolk Southern in the wake of the fiery, night-time derailment that NTSB Chairman Jennifer Homendy called 100% preventable. Toxic chemicals spilled and burned, resulting in community-wide concern about ongoing contamination and long-term health effects.

Meanwhile the NTSB will try and figure out what went wrong, with particular focus on the overheated bearing.

An overheated bearing is not the only problem that can cause a train to derail, but it's one that the industry has long known about.

Railcar bearings are essential to the safe and efficient operation of a train. Inside each bearing is a series of spinning rollers that surround both ends of a turning axle. When lubricated, they allow for limited friction while also supporting the weight of the railcar.

If a bearing gets too hot, usually from loss of lubricant, it can literally melt, causing it to seize up or come off the axle. The resulting damage can throw a railcar out of alignment and cause it to jump the tracks.

Robert Halstead, president of Ironwood Technologies, a railroad accident reconstruction firm in Syracuse, New York, said he's seen a bearing go from cool to molten in three to four miles.

"Usually, it's a good deal longer, he said. " … It can take tens of miles" depending on how quickly the lubricant leaks from the bearing.

The bearing in question was attached to one end of a wheelset – an axle and two rigid wheels – on a hopper car carrying plastic pellets. It was the 23rd car in a train of 149. A total of 38 cars derailed, including several carrying hazardous materials.

Most railcars run on four wheelsets, two in the front and two in the rear. The surface of the wheels and the rails they run on are tapered, resulting in just a dime's width of contact between the two as a train rolls down the tracks, said Steve Korpos, executive director of Midwest Railway Preservation Society in Cleveland's Flats. A one-inch flange on the inside of each wheel keeps the train from sliding off the rails.

Gravity helps keep everything in alignment.

In the old days of railroading, before the advent of trackside sensors, the only way to know if a bearing on a railcar was overheated was to conduct a physical inspection, said Nick Little, director for the Center of Railway Research and Education in the Broad College of Business at Michigan State University.

That task was often left up to "wheeltappers." When a train stopped in a yard or depot, they would walk past the cars with a long metal hammer tapping the wheels to make sure they were intact. If the tap let out a ring, all was good. A clunk meant trouble.

It was also the wheeltapper's job to look for problems with the axles and the bearings, Little said. If a bearing was too hot, it would radiate heat.

Train crews riding in a caboose could also scan the cars ahead while rounding a curve, looking for signs of smoke or fire, Halstead said. "And that worked back in the days when trains where shorter."

But times changed, and the industry eventually went to detectors. The result has been positive, Halstead said, with far fewer instances of a bearing going kaput and causing a major derailment.

"It's a pretty rare occurrence … that they actually go to failure," said Halstead, who declined to talk specifically about the East Palestine derailment because he has been retained by a law firm involved in the crash.

Hot bearing detectors like this one are placed along the rails to warn train crews when a bearing is getting overheated.Courtesy of Robert Halstead, Ironwood Technologies

A hot bearing detector is about one foot long and placed at the base of a rail, Halstead said. It has an oval-shaped hole in the middle through which the device scans for infrared radiation coming from a bearing.

As a train nears the detector, the device measures the outside temperature and then when the train goes over the device it measures the temperature of the bearings.

If a bearing temperature is too high compared to the outside temperature or in comparison to the bearing at the other end of the axle, then a computerized voice sends a warning that states the exact location of the problem.

The crew is then supposed to stop the train and do an inspection, Halstead said. One method of testing is to touch the bearing with a pen-shaped device called a tempilstic to see if it melts.

If the bearing is confirmed to be hot, the engineer knows to drag the train at a reduced speed to the next siding where the faulty railcar is taken out of service, Halstead said.

On the evening of Feb. 3, a detector along the Norfolk Southern track about 30 miles west of East Palestine recorded the faulty bearing on car No. 23 at 38 degrees Fahrenheit. At 20 miles out, another sensor recorded the bearing at 103 degrees. Neither temperature was high enough to trigger an alarm.

Moments before the crash, yet another sensor recorded the bearing at 253 degrees, above the triggering threshold of 170-200 degrees, and sent a warning signal to the crew.

But it was too late.

Norfolk Southern said it will examine sections of its core network where hot bearing detectors are more than 15 miles apart and develop a plan to add more "where practical due to terrain and operating conditions." The distance between its detectors currently averages 13.9 miles.

And the Association of American Railroads announced that all seven Class 1 railroads in the country have committed to adding roughly 1,000 detectors to close gaps between detectors.

"All Class 1 railroads have now agreed to go further and are immediately beginning to install additional (hot bearing detectors) across their key routes, with the goal of achieving average spacing of 15 miles, except if the route is equipped with acoustic bearing detection capability or other similar technology," the association stated.

Acoustic technology can detect a problem bearing based the sound emitted within a range of frequencies, Halstead said. Some of the detectors have been deployed already, he said, but an onboard version is still in test mode.

Norfolk Southern said it's working with manufacturers to develop better detectors, reevaluate triggering thresholds, and "to work with peers to analyze data for patterns that could provide earlier warnings of potential safety issues."

The Association of American Railroads said the industry is exploring further the advanced use of trending data to catch problems before they arise. It's been "relatively recently that software and data processing have led to the ability to proactively identify bearings that have not yet exceeded absolute temperature thresholds but that, based on (hot bearing detector) trending data, may become problematic and should be addressed."

Little, of the Center for Railroad Research and Education, believes the use of trending data is the way to go. He likens it to an early warning light in a car that comes on when tire pressure is getting low, but before the car needs to stop and take on air.

If a train crew is getting temperature readouts throughout its journey, it would know if a bearing is starting to heat up before stopping becomes necessary, he said.

"When a wheel bearing starts to go bad, it goes bad very quickly," Little said. "That's something that's been known about for a long time."

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