The operators of the Norfolk Southern train involved in a toxic derailment in East Palestine, Ohio, earlier this month received a "critical audible alarm message instructing the crew to slow and stop the train to inspect a hot axle," according to a newly released National Transportation Safety Board (NTSB) report Thursday.
The preliminary report said after hearing the warning from the hot bearing detector on Train 32N, the train’s engineer "increased the dynamic brake application to further slow and stop the train."
"The function of the HBD is to detect overheated bearings and provide audible real-time warnings to train crews," the report said.
"Train 32N passed three HBD systems on its trip before the derailment," adding that at the third system, it recorded "the suspect bearing's temperature at 253°F above ambient."
An undated aerial view of the train derailment in East Palestine, Ohio. (NTSB)
BUTTIGIEG VISITS OHIO TRAIN DERAILMENT SITE 20 DAYS AFTER WRECK
"After the train stopped, the crew observed fire and smoke and notified the Cleveland East dispatcher of a possible derailment. With dispatcher authorization, the crew applied handbrakes to the two railcars at the head of the train, uncoupled the head-end locomotives, and moved the locomotives about 1 mile from the uncoupled railcars," the NTSB wrote. "Responders arrived at the derailment site and began response efforts."
About 15,000 pounds of contaminated soil and 1.1 million gallons of contaminated water have been excavated from the site of the derailment, Norfolk Southern said Monday.
Dozens of rail cars, including 11 carrying toxic chemicals, derailed as the train passed through the town on the Ohio-Pennsylvania border. Officials conducted a controlled release of vinyl chloride three days after the derailment to avoid an explosion.
The NTSB said at the "time of the accident, visibility conditions were dark and clear; the weather was 10°F with no precipitation."
Investigators wrote that the train had 149 railcars, 20 of which were "hazardous materials tank cars transporting combustible liquids, flammable liquids, and flammable gas, including vinyl chloride." A total of 38 cars derailed.
Transportation Secretary Pete Buttigieg, left, speaks with a U.S. DOT official at the site of the East Palestine, Ohio, train derailment on Thursday. (Fox News)
While the train's crew was decelerating after hearing the hot bearing detector warning, "an automatic emergency brake application initiated, and train 32N came to a stop," NTSB investigators said.
Two days after the Feb. 3 derailment, responders extinguished the fire, but five cars carrying "115,580 gallons of vinyl chloride continued to concern authorities because the temperature inside one tank car was still rising," the NTSB said, leading to the controlled release.
Four of the cars containing the chemical were reported by the NTSB to be connected to each other, while the fifth was located in another part of the train.
"Responders scheduled a controlled venting of the five vinyl chloride tank cars to release and burn the vinyl chloride, expanded the evacuation zone to a 1-mile by 2-mile area, and dug ditches to contain released vinyl chloride liquid while it vaporized and burned," the report said.
"NTSB investigators identified and examined the first railcar to derail, the 23rd railcar," the report also said. "Surveillance video from a local residence showed what appeared to be a wheel bearing in the final stage of overheat failure moments before the derailment. The wheel bearing and affected wheelset have been collected as evidence and will be examined by the NTSB."
This video screenshot released by the U.S. National Transportation Safety Board shows the site of the derailed freight train in East Palestine, Ohio. (NTSB/Handout via Xinhua via Getty Images)
"The vinyl chloride tank car top fittings, including the relief valves, were also removed and examined by the NTSB on scene," the report added. "The top fittings will be shipped to Texas for testing under the direction of the NTSB."
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Investigators from the agency returned to the derailment site on Tuesday "to examine each [decontaminated] hazardous material tank car, document damage, and secure evidence for laboratory analysis."
"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 report concluded.
Fox News' Paul Best contributed to this report.
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