A fiery train derailment in North Dakota two years ago has once again highlighted the dangers of aging tank cars that the National Transportation Safety Board (NTSB) has been urging the rail industry to replace for decades. In its final report released Thursday, the NTSB concluded that the workhorse DOT-111 tank cars are long overdue for replacement, as their tendency to rupture in crashes magnifies the devastation when hazardous chemicals leak and ignite.
The derailment occurred on July 5, 2024, near the small town of Bordulac, North Dakota, when a CPKC train carrying a mix of hazardous materials and plastic pellets went off the tracks. The crash was triggered by a collapsed culvert that broke a rail, but the NTSB emphasized that the leak-prone tank cars made the resulting fire and chemical spill far worse.
Methanol spilled from five breached tank cars and caught fire, and three tank cars filled with anhydrous ammonia also ruptured in the blaze.
The NTSB noted that the worst rail disasters in recent memory—including the 2023 East Palestine, Ohio, derailment and the 2013 Lac Megantic derailment in Canada that killed 47 people—were all made worse by tank cars that leaked hazardous materials that caught fire. DOT-111 tank cars were also involved in numerous disastrous crude oil and ethanol derailments in the early 2000s.
Even some upgraded tank cars developed after previous derailments dating back to the 1990s are not adequate, the NTSB said, because they still have a thin outer shell.
Tougher newer rail tank cars are less likely to rupture in a derailment, the NTSB said. In addition, the agency recommended that railroads change how they assemble trains to ensure flammable liquids are not placed close to chemicals that could be toxic if inhaled.
Fortunately, the North Dakota derailment occurred in a sparsely populated area. Only two homes were voluntarily evacuated for two days while crews extinguished the fires and dealt with the spilled methanol and anhydrous ammonia.
No injuries were reported from the derailment itself, though a handful of cleanup workers sought treatment for health problems after working around the anhydrous ammonia.
The NTSB said the culvert that caused the derailment had been inspected frequently enough, but those exams were not thorough enough to identify the risk of a collapse ahead of time.
CPKC spokesman Patrick Waldron said the railroad received the report and is carefully reviewing it. Officials at the Pipelines and Hazardous Materials Safety Administration and the Association of American Railroads trade group did not immediately respond to questions about the NTSB findings.
The Federal Railroad Administration declined to comment immediately on the recommendations.
The NTSB has been recommending eliminating the use of DOT-111 cars for hazardous materials at least since the 1990s because of their history of problems. Congress did mandate that they be replaced for hauling flammable liquids by 2029, but even then they could continue to be used for other hazardous materials.