An overheating wheel bearing set off an audible alarm on the train before it derailed this month, according to a preliminary report from the National Transportation Safety Board.
EAST PALESTINE, Ohio — The crew of a Norfolk Southern freight train carrying toxic chemicals tried to slow the train moments before it derailed in the outskirts of East Palestine this month as an overheating wheel bearing set off an audible alarm on the train, an initial report from federal investigators found.
While the wheel bearing had steadily been heating up as the train traveled through Ohio, the alarm did not go off until a sensor registered that the wheel had reached 253 degrees above the ambient temperature, a preliminary report from the National Transportation Safety Board found. Two earlier sensors had not registered a temperature high enough to trigger an alarm, the report said.
The crew then saw fire and smoke and reported a possible derailment to the dispatcher. Five of the derailed cars were carrying 115,580 gallons of vinyl chloride, a colorless hazardous gas.
The report was released on Thursday as Pete Buttigieg, the transportation secretary, visited East Palestine. Mr. Buttigieg and other government officials have faced criticism over what some residents have viewed as a delayed response.
Norfolk Southern, the operator of the train, has also faced the wrath of residents and lawmakers over the derailment. A spokesman for the company did not immediately respond to a request for comment, but the company has repeatedly stressed its commitment to helping the area recover.
Since the train came off its tracks and officials agreed to burn off some of its hazardous cargo to avoid the threat of an explosion in early February, state and federal environmental officials have emphasized that initial tests have found the water and air to be safe, and did not show significant amounts of toxic chemicals.
But residents continue to report an array of lingering symptoms, including headaches and rashes, and have questioned whether it will be safe to continue to live there in the long term.