Initial details from the National Transportation Safety Board's investigation into the cause of the Norfolk Southern train derailment in East Palestine, Ohio, confirm the agency's earlier theory that a wheel-bearing overheated and broke just before the accident.
The agency will discuss the preliminary report today at 1pm.
The report said a defect detector installed along the tracks picked up on the failing bearing, which had reached a temperature of 253 F (123 C) above ambient temperatures.
The detector alerted the train crews to the abnormality, prompting the conductor to apply the trains' brakes, the NTSB reports. Once the train had slowed, the crew noted the train had caught fire and alerted emergency responders.
The had been traveling 47 mph (76kph) before the accident, which is slightly less than the 50 mph speed limit for locomotives. It passed two other default detectors farther back on the track — around 20 and 30 miles before the final detector — which did not register any malfunctions on the train.
According to the NTSB, the bearing that failed was located on the 23rd car in the 150-car train.
When the train derailed in East Palestine, 38 cars were scattered around the tracks near Taggart Road in East Palestine, Ohio, prompting emergency workers and Norfolk Southern officials to vent and burn the vinyl chloride gas that five of the railcars were carrying.
NTSB officials arrived on scene the day of the derailment and have been investigating the cause of the accident since.
The agency reviewed physical evidence collected from the site as well as surveillance footage from moments before the derailment to determine the cause of the crash.
While the NTSB determines the mechanical cause of the crash, politicians on both sides of the aisle have used the crash as a way to pummel their opponents in the lead up to the 2024 presidential election season.
Republicans have focused on Joe Biden's trip to Ukraine rather than East Palestine and US Transportation Secretary Pete Buttigieg's decision to wait several weeks to visit the crash site, claiming the men are ignoring the residents of the village. Mr Trump visited the village on Wednesday and made sure to hammer those points home, even asking the crowd if they thought Mr Biden would have money left for them after his visit to Ukraine.
Democrats have focused on pinning the systemic conditions contributing to the crash on Mr Trump. The Biden administration pointed out that it was Mr Trump's administration who rolled back rail safety regulations in 2017, reversing an Obama-era rule forcing rail companies shipping hazardous materials to equip a specific type of brake on their cars.
The railcars in the East Palestine crash were not equipped with those brakes.
