That part, known as the train’s wheel bearing, appeared to be in the “final stage of overheat failure moments before the derailment,” the National Transportation Safety Board (NTSB) report said, citing surveillance video.
The report also stated that a detector found the bearing to be 253 degrees Fahrenheit above the area’s air temperature.
Chairwoman Jennifer Homendy confirmed to reporters that the initial fire was started by a combination of an overheated axle and a car containing plastic pellets.
Homendy said there was no indication the train’s crew did “anything wrong.”
NTSB investigators have taken possession of the wheel bearing in question as well as the affected wheel mechanism, according to the report.
The investigation is ongoing and will further examine the design of the vinyl chloride tank cars and the derailment damage. It will also analyze the immediate response, in which first responders burned five vinyl chloride tank cars to prevent a possible explosion.
Homendy predicted the full investigation would take between 12 and 18 months.
Read the full story at TheHill.com.