The report laid out the basic sequence of events leading up to the decision by the Ohio and Pennsylvania governments to evacuate nearby residents and conduct a “controlled release” of the burning chemicals to alleviate the risk of an explosion.
The accident happened on the Fort Wayne Line of Norfolk Southern’s Keystone Division. The railway is one half of a corporate duopoly that dominates freight rail operations in eastern North America, alongside CSX Transportation, and the Keystone Division is centered on its Pennsylvania-based acquisitions.
According to the report, the 23rd car of the train, the first to derail, suffered a failure of one of its axles after it overheated - a situation called a “hotbox.” The NTSB found that several hot bearing detectors (HBDs) set up at mileposts along the tracks showed a steady increase in the axle’s temperature as the train made its way eastward, with it triggering a “critical” alarm at milepost 49.81 - just outside of East Palestine.
18 February 2023, 00:04 GMT
The detector near East Palestine found the axle was 253 degrees Fahrenheit above normal. At the previous detector in Salem, 20 miles to the west, the axle had been 103 degrees Fahrenheit above normal.
Those details corroborate security camera footage that emerged after the accident, which showed the wheels of a train car on fire as it passed the previous HBD in Salem. The NTSB noted the train was moving at 47 miles per hour when the brakes were applied - just under the 50 mph speed limit for that stretch of track. At that speed, it would have taken about 25 minutes to go from Salem to East Palestine.
The standard for “critical” was defined by Norfolk Southern, not the NTSB, and when the alarm sounded, the train operator applied the brakes. However, it was already too late by that point, and the car became derailed, taking with it 50 railcars, which exploded into flames.
Local fire departments battled the flames for several hours and successfully snuffed them out, but a deeper problem remained, the NTSB report said. That situation led to a massive release of toxic gases into the atmosphere at the decision of the Pennsylvania and Ohio state governments.
Of the derailed cars, 14 were carrying vinyl chloride, an ingredient in PVC. Five of them, together carrying 115,580 gallons of vinyl chloride, posed a special danger even after the fire was put out: the temperature inside the cars continued to rise, leading authorities to fear a polymerization reaction was underway inside the cars that posed a risk of explosion. They made the decision to carry out a controlled venting of the five cars and the burning of the vinyl chloride, which took several hours.
The fire turned the vinyl chloride into the toxic gases of hydrogen chloride and phosgene: the former is a key ingredient in hydrochloric acid and the latter was used as a chemical weapon during World War I and was responsible for killing 85,000 soldiers. Although authorities assured residents the area was safe and allowed them to return, many have complained of headaches and trouble breathing for dozens of miles around the crash site, and thousands of fish, pets, and livestock have been discovered dead.
The NTSB noted that all the railcars carrying toxic chemicals had been decontaminated and were being tested by NTSB investigators.
“The NTSB’s investigation is ongoing. Future investigative activity will focus on the wheelset and bearing; tank car design and derailment damage; a review of the accident response, including the venting and burning of the vinyl chloride; railcar design and maintenance procedures and practices; NS use of wayside defect detectors; and NS railcar inspection practices,” the agency noted.
The Biden administration has variously blamed Norfolk Southern and the administration of his predecessor, Donald Trump, for the accident, accusing both of neglecting the adoption of important safety technologies.
While both statements are true, railway workers have also called attention to intervention in a pending rail strike late last year by Congress and the White House, ordering rail workers not to walk off the job and threaten the country’s economy. Those workers were demanding, among other things, safer working conditions, including better staffing on trains and shorter hours, saying they were massively overworked.