Has the root cause of the Ohio train derailment (that led to the Ohio chemical cloud) been found?
Update: 24th Feb 2023- The NTSB has released a preliminary report regarding the Ohio train wreck here.
Background
You probably know by now about the Ohio train derailment accident that took place about two weeks ago, where a 150 car train carrying various chemicals met with an accident near East Palestine Ohio. As a result of the derailment, 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—11 of which derailed. There were no reported fatalities or injuries
Other cars contained cargo like cement, frozen vegetables, etc. The train was operated by Norfolk Southern.
This derailment apparently led to some of the cars catching fire. Fire fighters were brought in to control the blaze.
Some of the chemical containers were carrying Vinyl Chloride, a hazardous chemical that is known to react violently if exposed to air and cause an uncontrolled explosion.
Since this was a real possibility, the authorities decided to purposefully explode it (in order to prevent an uncontrolled explosion later on). This was apparently carried out and it led to a bigger fire than the original one, with huge plumes and a large toxic cloud that is now referred to as the infamous Ohio chemical cloud.
Other chemicals in the derailed cars included ethylene glycol, monobutyl ether, ethylhexyl acrylate and isobutylene. All of these are highly toxic chemicals and oxidation of these chemicals (fire) can give rise to other toxic chemicals.
The Vinyl chloride fire led to formation of highly poisonous gases including highly hazardous toxic materials like Hydrogen Chloride gas and Phosgene (which was actually used a Chemical weapon during World War I). Additionally the other chemicals and their compounds after oxidation gave rise to a chemical cloud over Ohio which is a toxic mixture of the various components that formed after the
Consequential Damages
The consequential damages of this accident and the controlled explosion have been huge. The entire area for miles around the accident site in East Palestine had to be evacuated. However even after residents returned, they found the air to be contaminated, leading to throat irritation, headaches and other effects.
Several animals in the area were found dead including foxes (in a fox keepers premises), dogs and chickens. The Ohio river has also got polluted with reports of dead fish and frogs.
The EPA (Environmental Protection Agency) is monitoring the air outdoors. Also, the agency has screened indoor air quality in approximately 500 homes, but no vinyl chloride or hydrogen chloride have been identified. So it is not clear what other chemicals are present in the air that are causing such issues.
However some people believe that the water bodies in the area still remain polluted, as the below tweet shows.
Visited a local creek in East Palestine today. These waterways are still very polluted. It’s time for Norfolk Southern to finish the cleanup. Check this video out: pic.twitter.com/4lsHBmrMJj
— J.D. Vance (@JDVance1) February 16, 2023
Root cause of the Ohio train derailment found?
Although there is no official confirmation, a root cause of this incident seems to have been found. Beware that at this point it is still a conjecture.
When the train was passing by an industrial facility several tens of miles before the place where the train derailed, surveillance camera footage shows sparks and flames coming out from the undercarriage. (These cameras were mounted on the facility perimeter and the train track was within range).
This phenomenon could happen due to axle wheel bearings being in a bad condition, which can lead to localized heating and hot spots. A hot box detector also apparently detected this.
Hot box detectors are devices that are placed next to railway tracks precisely to check for such issues such as undercarriage axle hot spots. This information is relayed to the Railway control center and/or the train crews, that then bring the train to a safe halt and then carry out an inspection.
In this case, apparently the train crew also noticed this problem and applied emergency braking to stop the train. Did this cause the derailment? Probably until some new facts emerge that disprove the theory.
Meanwhile the NTSB (National Transportation Safety Board) is investigating this accident and it is expected to come out with a report in the next two weeks, that will shed more light on the exact sequence of events that happened. The NTSB can also issue urgent recommendations at any point during the investigation.
The NTSB has issued a press release that states among other things- parties to the NTSB investigation provide technical assistance. They 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.
Risk Assessment Studies
We do not have any information whether any risk assessment studies were conducted for transporting hazardous chemicals via train. If such studies including techniques like HAZOP or What-If analysis were conducted then one of the scenarios/deviations might have been derailment due to mechanical issues and/or ignition of the chemicals due to sparks/flames due to failed wheel bearings.
Finally, note that all Industrial accidents are preventable. We should aim to have zero industrial accidents ever. Get more information about other Industrial accidents here.
