THE United States National Transportation Safety Board (NTSB) released a preliminary report on its investigation into the Norfolk Southern (NS) derailment at East Palestine, Ohio, on February 23.

The NTSB investigation of the derailment of eastbound NS train 32N on February 3, carrying vinyl chloride and other freight, is ongoing. The report provided initial findings or factual information only.

According to NTSB, 38 wagons derailed on main track 1 of the NS Fort Wayne Line of the Keystone Division in East Palestine. Of those, 11 were “carrying hazardous materials that subsequently ignited, fuelling fires that damaged an additional 12 non-derailed wagons,” the agency reported. “First responders implemented a 1.6km evacuation zone surrounding the derailment site that affected up to 2000 residents. There were no reported fatalities or injuries.”

The 149-car train included two head-end locomotives and one distributed power locomotive located between wagons 109 and 110. According to the NTSB, the consist included 20 placarded hazardous materials (hazmat) tank cars carrying combustible liquids, flammable liquids and flammable gas, including vinyl chloride. The train was travelling at about 75.6km/h at the time of the derailment, less than the maximum authorised speed of 80km/h.

Train movements near the derailment site are authorised by cab signals and wayside signal indications with an overlaid positive train control (PTC) system and are coordinated by the NS Cleveland East dispatcher located in Atlanta, Georgia. The PTC system was enabled and operating at the time of the derailment, NTSB says.

“Train 32N was operating with a dynamic brake application as the train passed a wayside defect detector on the east side of Palestine, Ohio, at milepost (MP) 49.81.4,” NTSB reported. “The wayside defect detector, or hot bearing detector (HBD), transmitted a critical audible alarm message instructing the crew to slow and stop the train to inspect a hot axle. The train engineer increased the dynamic brake application to further slow and stop the train. During this deceleration, an automatic emergency brake application initiated, and train 32N came to a stop.

“Train 32N passed three HBD systems on its trip before the derailment. At MP 79.9, the suspect bearing from the 23rd car had a recorded temperature of 3°C above ambient temperature. When train 32N passed the next HBD, at MP 69.01, the bearing’s recorded temperature was 39.4°C above ambient. The third HBD, at MP 49.81, recorded the suspect bearing’s temperature at 122.7°C above ambient.

“After the train stopped, the crew observed fire and smoke and notified the Cleveland East dispatcher of a possible derailment. With dispatcher authorisation, the crew applied handbrakes to the two wagons at the head of the train, uncoupled the head-end locomotives, and moved the locomotives about 1.6km from the uncoupled wagons. Responders arrived at the derailment site and began response efforts.”

NTSB staff examine one of the wagons.

NTSB says that while on scene, its investigators examined equipment and track conditions; reviewed data from the signalling system, wayside defect detectors, local surveillance cameras, and the lead locomotive’s event recorder and forward-facing and inward-facing image recorders; and completed interviews. They identified and examined the first wagon to derail, the 23rd in the consist.

“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,” NTSB reported. “The wheel bearing and affected wheelset have been collected as evidence and will be examined by the NTSB. The vinyl chloride tank car top fittings, including the relief valves, were also removed and examined by the NTSB on scene. The top fittings will be shipped to Texas for testing under the direction of the NTSB.”

According to NTSB, the hazmat tank cars have been decontaminated. NTSB investigators returned to Ohio on February 21 to examine each hazmat tank car, document damage and secure evidence for laboratory analysis.

NTSB said that its “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; wagon design and maintenance procedures and practices; NS use of wayside defect detectors; and NS wagon inspection practices.”