This photo taken with a drone shows portions of a Norfolk Southern freight train that derailed Friday night in East Palestine, Ohio are still on fire at mid-day Saturday, Feb. 4, 2023. (AP Photo/Gene J. Puskar)

The National Transportation Safety Board issued an update Tuesday on the investigation of the Feb. 3 train derailment in East Palestine, saying a preliminary report is expected in two weeks.

According to the email, the Washington, D.C.-based agency is continuing to work on determining what caused the derailment and evaluate the emergency response efforts.

“NTSB investigators have identified and examined the rail car that initiated the derailment. Surveillance video from a residence showed what appears to be a wheel bearing in the final stage of overheat failure moments before the derailment. The wheelset from the suspected railcar has been collected as evidence for metallurgical examination. The suspected overheated wheel bearing has been collected and will be examined by engineers from the NTSB Materials Laboratory in Washington, D.C.,” the written update said.

Once the decontamination of tank cars is finished, NTSB investigators will return to the site to complete a thorough examination of the tank cars.

“The vinyl chloride tank car top fittings, including the relief valves, were removed and secured in a locked intermodal container pending an NTSB examination. Once the fittings are examined by NTSB investigators, they will be shipped to Texas for testing, which will be conducted under the direction of the NTSB.

“NTSB has obtained locomotive event recorder data, forward- and inward-facing image recording data and wayside defect detector data. NTSB investigators continue to review documentation, event recorder data and perform interviews,” according to the update.

The NTSB noted that the Norfolk Southern general merchandise freight train derailed at 8:54 p.m. Feb. 3. The report said “38 rail cars derailed and a fire ensued which damaged an additional 12 cars. There were 20 total hazardous material cars in the train consist — 10 of which derailed. A list of what the derailed rail cars were carrying is available online. There were no reported fatalities or injuries.”

The list in the hazardous class included flammable gases vinyl chloride and isobutylene, flammable liquids benzene and butyl acrylates, combustible liquids ethylene glycol mono butyl ether and ethylhexyl acrylate. Other items on the list included polyethylene, petroleum lube oil, polypropyl glycol, propylene glycol, diethylene glycol, petro oil, dipropylene glycol, semolina, polyvinyl, fuel additives, sheet steel, frozen vegetables, paraffin wax, powder flakes, hydraulic cement, passenger autos and malt liquids.

The email said the “NTSB is conducting a safety investigation to determine the probable cause of the derailment and issue any safety recommendations, if necessary, to prevent future derailments. The NTSB can also issue urgent recommendations at any point during the investigation. All questions regarding the safety investigation should go to NTSB.”

The update said emergency response will be a factor in the investigation, but noted the NTSB is not involved in air monitoring, testing of water quality, environmental remediation or the evacuation orders.

Questions on environmental issues should be referred to the Environmental Protection Agency. Learn more at: East Palestine Train Derailment – EPA OSC Response.

Parties providing technical assistance in the NTSB investigation include: U.S. Department of Transportation’s Pipeline and Hazardous Materials Safety Administration and Federal Railroad Administration, Ohio State Highway Patrol, the Village of East Palestine, Norfolk Southern Railway, Trinity Industries Leasing Company, GATX Corporation, Brotherhood of Railway Carmen, International Association of Sheet Metal, Air, Rail and Transportation Workers and Brotherhood of Locomotive Engineers and Trainmen.

NTSB board member Michael Graham hosted two press briefings last week in East Palestine. They can be viewed on the NTSB YouTube channel.

During the press conference on Feb. 5, Graham said members of the three-member train crew were interviewed and included the engineer, conductor and conductor trainee. None of them were injured and no injuries were reported at the scene.

Graham said “the crew did receive an alarm from a wayside defect detector shortly before the derailment indicating the mechanical issue, then an emergency brake application initiated.”

At the time, he said two videos obtained by NTSB showed preliminary indications of a possible mechanical issue with one of the rail car axles.