The derailment of a goods train carrying hazardous cargo in Ohio, USA has led to widespread outrage among the local residents and some intense soul searching among the responsible authorities. We will do well to pay heed to the lessons unravelling from the incident as rail transport of chemicals is poised to expand both in volume and reach in the country.
On 3rd February a goods train derailed in the state of Ohio, USA. The train was carrying hazardous cargo which spilled over on the tracks and adjoining area. There was no loss of life. The alacrity with which the authorities responded and launched an investigation into the incident holds lessons for us in India, where bulk transportation of chemicals is growing bigger and getting more widespread.
The Incident
The 2.7-kilometre-long goods train had 149 railcars, out of which 20 were reportedly carrying hazardous cargo. The derailment, which occurred a little before 9 pm local time, knocked 38 rail cars off the rails and the ensuing fire affected an additional 12 railcars. The hazardous cargo in the rail cars that were affected by the derailment included vinyl chloride, butyl acrylate, ethylhexyl acrylate, isobutylene and benzene. Five railcars were carrying a total of 43,000 litres of vinyl chloride, a confirmed carcinogen. These five railcars posed the greatest threat, especially as the temperature inside one of them was steadily rising indicating the onset of polymerisation. To avoid the possibility of a runaway reaction and explosion, the authorities released the contents into a ditch and burned it off three days after the incident. The controlled burning of vinyl chloride produced a massive fireball and images of columns of black smoke went viral on social media. Following this the nearby residents reported experiencing headaches, dizziness and nausea. Though there was no loss of human life, thousands of fish were reportedly killed in the nearby waterways following the spill.
Investigation
National Transportation Safety Board (NTSB) of USA was prompt in launching an investigation and the preliminary report is rich in details. At the time of the derailment the train was reportedly travelling at 75 kilometre per hour, just under the maximum speed limit of 80 kilometre per hour. An automated safety system known as “positive train control” was enabled and operational. The train carried three crew members – the locomotive engineer, the conductor and a trainee – and the report did not find any wrongdoing on their part. Video footage of the train before derailment reveals sparks flying from underneath the train, most probably from an overheated wheel bearing. A public report from NTSB will take 12-18 months, but the preliminary report attributes the incident to a bearing failure.
Bearing Failure
The wheel bearing failure happened on the 23rd railcar of the goods train. The overheating of the bearing was picked up by sensors provided on the railroad lines. Three such sensors, known as hot-box detectors, were available along the 50-kilometre stretch near the site of the derailment. They recorded the overheating of the suspect wheel bearing. The first detector registered a temperature of 21 degrees C above the ambient temperature. When the train reached the second detector located 18 kilometres away, the temperature had risen to 57 degrees C above the ambient. The third detector recorded a temperature of 140 degrees C above ambient and this triggered an alarm for the crew to halt the train and inspect the bearing. When the train was decelerating the wheel bearing failed leading to the derailment. The train company’s safety guidelines require crew to initiate action only when the bearing temperature crosses a threshold on 95 degrees C above the ambient. Because the detectors were spaced too far apart, the wheel bearing heated up beyond the train crew’s ability to halt it safely.
Design Flaws
NTSB’s investigation is far from over. They will review the safety equipment and procedures of the Norfolk Southern, the private train company, to see if the catastrophic failure could have been avoided. The spacing of detectors on rail tracks and the temperature at which they trigger alarms are not presently governed by any law and they vary from operator to operator. Had there been an additional detector between the second and the third, the train could have been brought to a safe halt before the bearing got compromised. NTSB also plans to examine whether vinyl chloride should be transported in more robust railcars. Also on the anvil is revisiting the definition of “high hazard flammable train” which is reserved for trains carrying crude and petroleum products. These trains would have electronically controlled pneumatic brakes, which according to studies are better than the air brakes that were present in the Ohio train. Electronic brakes may have decreased the number of derailed railcars.
Environment
US Environmental Protection Agency (EPA) set up air quality monitoring stations near the derailment site and also collected soil and water samples from the surrounding areas. A dam was constructed to contain the contaminated firefighting water at the site. Absorbent pads and vacuum trucks were used to recover the spilled chemicals. EPA has ordered Norfolk Southern to cover the full cost of cleaning up the aftermath of the train crash. Norfolk Southern has drawn up a plan to clean up the site including digging wells to test and monitor groundwater. The company also plans to take a series of measures moving forward to minimise the long-term impacts of chemicals on the land and groundwater, including ripping up the tracks where the train derailed and removing soil underneath.
Emergency Response
The authorities continue to receive lot of flak on the way they handled the situation in the days following the incident. Evacuation was mandatory within a 1.8-kilometre radius but many refused to comply with the order. 500 residents chose to stay put and this noncompliance was noticed only 3 days later, whereupon the authorities decided to act aggressively. People were posting their reasons for not complying with the evacuation order on social media which the authorities failed to monitor. Many residents and local officials have expressed frustration that the authorities failed to adequately communicate the severity of the incident, leading many to ignore the evacuation order. The incident has been an eye-opener on the effectiveness of emergency management procedures.
Lessons for India
In India, 57% of chemical distribution is through road and rail accounts for only 37%. But this is poised to change as many companies want to bring down their carbon footprint by adopting rail movement of their raw materials and products. The Ohio derailment holds many lessons for Indian chemical industry including logistics service providers.
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