Who's at fault in the catastrophic East Palestine train derailment?

When a wheel bearing overheated on a train carrying five tank cars of vinyl chloride through East Palestine, Ohio, on February 3, a sequence of events began that turned into a major accident with nationwide political implications.

Overheated bearings (so-called "hot boxes") are not new to railroading. With the thousands of wheel bearings in use every day, it's almost inevitable that some of them will fail by running hot and basically grinding themselves to pieces. What is new in the last few decades are a number of safety devices that the railroads have installed to deal with overheated bearings.

 

 

The Ohio train's bearing was sensed by three track-side hot-bearing detectors. The National Transportation Safety Board (NTSB) has determined that one sensor noted the suspect bearing was warm (38°F above ambient, which was a cold 10°F) about 20 minutes before the derailing occurred. Ten miles and 12 minutes or so later, it had heated up to 103°F above ambient. The detector system's threshold was set so that these readings did not set off an audible alarm in the cab. But the third sensor's reading of 253°F did.

By that time, it was too late. Trains up to a mile or more long can't be stopped on a dime. Three crew members were on the train, all in the lead engine. By the time the engineer stopped the train, they could see fire and smoke behind them. The train dispatcher authorized the crew to set hand brakes on the lead cars and move the front engines a mile or so down the track to safety.

A total of 38 railcars had left the tracks, and the ensuing fire damaged 11 more. Firefighters determined during the following two days that some intact tanks of vinyl chloride were heating up. This chemical, which is used to make the ubiquitous plastic PVC (polyvinyl chloride), can undergo a spontaneous polymerization reaction that can cause an explosion. To avoid that dire consequence, firefighters released the vinyl chloride into ditches they had dug nearby and burned it.

Subsequent news coverage has dealt with the environmental consequences of the release of vinyl chloride and other toxic chemicals into the air, water, and soil around East Palestine. One news report says monitors have estimated about 43,000 animals have perished, but 38,000 or so of that number were non-endangered minnows. Residents have complained of odd tastes in the drinking water and air, and extreme measures have been and will be taken to clean up the extraordinary mess that several tank cars of toxic chemicals can make.

In an interview, NTSB chair Jennifer Homendy said that the accident was "100% preventable." On the face of it, that makes railroad operator Norfolk Southern look pretty bad. But exactly how could this accident have been prevented?

Certain safety requirements such as advanced braking systems for "high-hazard" trains that the Biden White House said the Trump administration removed would not have made a difference in this case, according to Homendy. So attempts to turn the accident into a political football seem to amount to more smoke than fire, so to speak.

Norfolk Southern may rethink their thresholds for hot-box detectors. This particular bearing seems to have gone from barely sensibly warm to disintegrated in less than 30 minutes. The spacing and sensitivity of such detectors is a matter of engineering judgment, and accidents have a remarkable way of leading designers to reconsider safety precautions and adjust them so that the previous accident, at any rate, will not happen again.

Too low a threshold on the detectors would mean that the trains are stopping needlessly, as a bearing may run warm for some unknown time before it fails. Only the railroads have the statistics on these kinds of problems, but now that we know what can go wrong if the detection system doesn't stop the train in time, there may be a lot of readjusting going on in the future.

Some statistics from the Federal Railroad Administration cited by National Review say that train accidents caused by axle and bearing-related failures have fallen 59 percent from 1990 to 2019, largely due to the use of hotbox detectors. So far from doing nothing about the problem, the railroads have been steadily improving their performance in this regard.

Sociologist Charles Perrow devised the term "normal accident" to express the type of mishap that very complex systems such as nuclear reactors can produce when multiple interacting parts do something that is very hard to predict, let alone forestall. The East Palestine derailment was not that complicated. But the system that should have prevented it failed in this case, and because of the particular cargo being carried, the consequences were awful.

Despite an apocalyptic-looking crash scene, no one was killed or even injured in the derailment or fire. This accident was far less consequential in that sense than the one, also involving derailed tank cars, that devastated the town of Lac-Mégantic, Quebec, on July 6, 2013 and killed 47 people. So as bad as the East Palestine situation is, it could have been much worse.

Norfolk Southern is going to be paying for the consequences of this accident for a long time. Already, millions of gallons of contaminated firefighting water have been shipped to Deer Park, Texas, where a specialist firm will inject it deep underground. While some would question the propriety of this type of disposal method, Deer Park is in the middle of the most concentrated cluster of oil refineries and petrochemical plants in the US, and a little vinyl-chloride-contaminated water way beneath their feet will trouble Deer Park residents not at all.

Someone will have to pay for all the contaminated dirt to be dug up and shipped somewhere else, and so East Palestine is getting more national attention and commerce, although of an undesirable kind, than the mayor and city council ever dreamed of. While I hope that life returns to whatever passes for normal in eastern Ohio, East Palestine will never be the same again.

 

This article has been republished with permission from the author’s blog, Engineering Ethics.  

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