The National Transportation Safety Board said Tuesday, June 25, 2024, that a rail car’s defective wheel bearing caused the derailment and subsequent hazardous material release in East Palestine, Ohio, last year.

NTSB investigators said that the derailment occurred when a bearing on a hopper car failed and overheated, leading to the fiery February 3, 2023, derailment in the center of the small Ohio town. 

NTSB investigators, speaking at an NTSB board meeting held on June 25, 2025, at East Palestine High School, said the decision by the local incident commander three days later to conduct a vent and burn of the contents of the tank cars carrying vinyl chloride monomer was based on incomplete and misleading information provided by Norfolk Southern officials and contractors. The vent and burn was not necessary to prevent a tank car failure, NTSB investigators found.

According to the Federal Railroad Administration, a vent and burn procedure should be a last resort, used when a tank car is about to fail. Norfolk Southern rejected three other removal methods and began planning for a vent and burn shortly after the derailment, investigators found.

Contributing to the severity of the hazardous materials release was the continued use of DOT-111 tank cars to transport flammable liquids and other hazardous materials. 

During the derailment, three DOT-111 cars were mechanically breached, releasing flammable and combustible liquids that ignited. The fire spread and exposed other tank cars to heat, leading to a decision to conduct vent-and-burn action on five tank cars carrying vinyl chloride. The vent and burn resulted in a mushroom cloud that towered over the town and surrounding area. 

The DOT-111 tank car is being phased out of flammable liquids service because of its long record of inadequate mechanical and thermal crashworthiness and propensity to release lading in a derailment. This unacceptable safety record is why the NTSB is calling for an accelerated phaseout of DOT-111 tank cars in hazmat service.

Overheated wheel bearings are a common cause of rail accidents. Hot bearing detectors are part of system intended to warn crews to stop the train before the hot bearing can cause a derailment. 

The crew did not receive a hot bearing warning until the train passed over a detector in East Palestine, when the overheated bearing was about to cause its axle to fail. The crew began to slow the train using dynamic braking, but it was too late. A total of 38 rail cars derailed, including 11 rail tank cars carrying hazardous materials. 

The difficulty of accurately measuring temperature inside the bearing, combined with Norfolk Southern’s standard operating procedures and the spacing between detectors, meant the crew did not receive adequate warning to stop the train before the derailment, NTSB investigators said.

“Unfortunately, some have sought to minimize the wide-ranging impacts of this derailment, pointing to the fact that there were no fatalities or injuries. For this, we are certainly grateful, but the absence of a fatality or injury doesn’t mean the presence of safety,” said NTSB Chair Jennifer Homendy. “Our agency doesn’t wait for death or injury to occur. Instead, we objectively analyze the facts and evidence to make recommendations that, if implemented, will ensure this never happens again. Thanks to the hard work of our world-class investigators, we now have a roadmap to do just that.”

As a result of this investigation, the NTSB issued new safety recommendations to the Secretary of Transportation, FRA, PHMSA, the state of Ohio, the Association of American Railroads, Columbiana County Emergency Management Agency, the Chlorine Institute, Norfolk Southern Railway, the International Association of Fire Chiefs, the International Association of Fire Fighters, the American Chemistry Council, Oxy Vinyls, LP and the National Volunteer Fire Council. The recommendations address safety issues including:

• Failure of wayside monitoring systems to diagnose a hot wheel bearing in time for mitigation to prevent a derailment.
• Inadequate emergency response training for volunteer first responders.
• Hazardous materials placards that burned away, preventing emergency responders from immediately identifying hazards.
• A lack of accurate, timely and comprehensive information passed to local incident commanders and state officials.
• The continued use of DOT-111 tank cars in hazmat service.

An abstract of the final report, which includes the findings, probable cause, and all safety recommendations, is available online. The full final report will publish in the next few weeks.

The docket for the investigation is available online.