The National Transportation Safety Board released a four-page preliminary report on the February 3 train accident in East Palestine, Ohio. The report lays out the timeline of what occurred and confirms some details that earlier reports had suggested.

What the NTSB Said

The Norfolk Southern train derailed at 8:54 p.m. on February 3 on the Fort Wayne Line between Chicago and Pittsburgh. Weather was clear, with no precipitation and cold temperatures. The train had 149 cars, 20 of which were carrying hazardous materials. The train had two locomotives at the head and one locomotive between cars 109 and 110. (Placing a locomotive in the middle of a train is called “distributed power,” and it helps to operate long trains more safely. The distributed-power locomotive operates by radio connection with the head locomotives to allow a more even application of traction throughout the train.)

Thirty-eight total cars derailed, of which eleven were carrying hazardous materials. The hazardous materials started on fire, which caused damage to an additional twelve non-derailed cars and caused first responders to implement a one-mile evacuation zone that affected up to 2,000 people.

The train was traveling at 47 miles per hour when it derailed, below the speed limit of 50 miles per hour. The positive-train-control system, which is in place on all major freight lines in the country and enforces proper spacing and speed of trains, was enabled and operating as normal.

An overheating wheelset was the cause of this derailment, and the NTSB has identified the exact wheelset that caused it. The train passed three wayside hotbox detectors before it derailed. Hotbox detectors are safety devices that use infrared sensors to measure how far the temperature of the wheelset is above the ambient temperature. The NTSB listed two temperature thresholds where the engineer should stop the train in response to a hotbox detector reading:

If the reading is between 170°F and 200°F above ambient temperature, it’s a non-critical warm bearing that should be inspected.
If the reading is greater than 200°F above ambient temperature, it’s a critical warm bearing, and the railcar should be removed.

When the train passed the first hotbox detector at milepost 79.9, the bearing on the car that caused the derailment was at 23°F above ambient temperature. When it passed the second hotbox detector at milepost 69.01, it was 103°F above ambient temperature. When it passed the third hotbox detector at milepost 49.81, it was 253°F above ambient temperature.

The train’s dynamic brakes were in operation when the train passed the third wayside detector. (Dynamic brakes use energy from the locomotive’s engine to slow the train. They are commonly used to hold to a speed limit or shave off a few miles per hour while a train is in motion. That the dynamic brakes were in operation indicates that the engineer was attentive and doing what he should to maintain a safe operating speed.)

In response to the third hotbox detector, the engineer increased dynamic-braking pressure, and while the train was decelerating, an automatic emergency brake initiated and stopped the train. (That is what he should have done, and the emergency system worked as it should have.)

The crew then got out and observed fire and immediately notified the Norfolk Southern dispatcher in charge of that section of the line. They applied handbrakes to cars at the front of the train and detached the locomotives, then first responders arrived on the scene to put out the fire.

The fire was out by February 5. At that point, over a day after the initial derailment, responders addressed concerns about the vinyl chloride gas in five derailed cars. The temperature of the gas in one of the cars was still rising, indicating that it could explode. To prevent that, they decided to vent the vinyl chloride and burn it off, beginning at 4:40 p.m. the next day, February 6, which is what led to the images of plumes of smoke filling the sky above East Palestine. They expanded the evacuation zone and dug ditches to contain excess vinyl chloride, which turns into a liquid once released from the tank cars.

The NTSB says it will further investigate the equipment it has recovered from the accident, the accident response, and Norfolk Southern’s practices.

Evidence Points to a Freak Accident

The NTSB’s preliminary report confirms what some initial reports had suggested about the nature of the accident. There is not any evidence in this report that the crew did anything wrong. They were adhering to the speed limit, and they responded correctly to the promptings of the safety devices. The first two hotbox detectors did not show cause for concern. It was not until the third one that the crew should have reacted, and it did.

The train’s emergency braking system went into effect as it should have to stop the train. It seems that the wheelset failure occurred at a very inopportune time, reaching critical heat levels right before a hotbox detector after being comfortably within safe operating levels at the previous hotbox detector. Regardless of which braking system is in use — including the much-hyped electronically controlled pneumatic (ECP) brakes that the Department of Transportation has been talking about — it takes a while to stop a freight train.

The idea that the failure of a past regulatory effort to mandate ECP brakes on high-hazard flammable trains (HHFT) contributed to this accident is absurd. First, the issue seems to have been the timing of the hotbox-detector reading, and there was no brake failure. Second, this train was a general-merchandise train, and it was properly classified as such. The HHFT designation only applies to trains with “a continuous block of 20 or more tank cars loaded with a flammable liquid or 35 or more tank cars loaded with a flammable liquid dispersed through a train,” according to the DOT. This train only had three cars carrying flammable liquids, and only one of those cars was breached in the accident. Vinyl chloride is a gas, and is consequently and properly subject to different regulations. The vast majority of the train was non-hazardous. No iteration of the failed ECP-brake regulation would have applied to this train.

Another component of HHFT regulations is that they are always restricted to a speed limit of 50 miles per hour. That was already the speed limit on this section of track, and the train was going 47 miles per hour, so that portion of the designation is also irrelevant.

The decision to vent and burn the vinyl chloride seems to have been taken with great deliberation and caution. The NTSB says responders were aware of the rising temperatures in one of the cars on February 5, but the venting only began in the late afternoon of February 6. That suggests it was not a decision that was taken lightly, and with good reason, considering the images we all saw of the burn.

No part of Secretary of Transportation Pete Buttigieg’s policy response to the accident would have prevented the accident, based on the evidence the NTSB has so far released. Top areas of interest as the investigation progresses are whether responders were right to vent and burn the chemicals, whether anything different could have been done concerning hotbox detectors, and whether the car that started the derailment was properly inspected. The gap between the first two hotbox detectors was 10.89 miles, but the gap between the second and the third, where the overheating occurred, was 19.2 miles. Both of those distances are below the national average of approximately 25 miles that the Federal Railroad Administration noted in a 2019 report. Whether the cost of installing more hotbox detectors would be worth the benefit is a question worth further study. They have already significantly increased safety. “Train accident rates caused by axle and bearing-related factors have dropped 81 percent since 1980 and 59 percent since 1990 due to the use of [hotbox] detectors,” the FRA report said.