UL Research Institutes’ Fire Safety Research Institute has released a new report examining the dangers posed by lithium-ion battery fires involving electric micromobility devices aboard passenger trains.
The report, Recommendations to Improve Passenger Railcar Safety During Electric Micromobility Vehicle Fires, analyzed railcar conditions during thermal runaway incidents involving devices such as e-bikes, standing e-scooters and seated e-scooters.
Researchers conducted experiments inside a full-size intercity passenger railcar, measuring heat exposure, toxic gas concentrations and the impact on passenger evacuation conditions. Support and fire suppression assistance during the testing was provided by the Fire Department of the City of New York and Christiana Fire Company.
According to the findings, passengers located within 10 feet of a burning e-mobility device could become rapidly incapacitated due to extreme heat exposure, while all passengers on board faced risks from toxic smoke generated by the fire.
The study found that most passengers would likely not recognize the danger posed by a failing lithium-ion battery until smoke suddenly vented from the device. Once flames ignited, smoke spread to the opposite side of the railcar within 30 seconds, while visibility throughout the carriage was lost in under four minutes. Researchers also noted that devices typically emitted smoke for only a few seconds before igniting.
Toxic gas measurements showed that conditions inside the railcar would have significantly reduced survivability between three-and-a-half and seven minutes after ignition.
“We’ve already seen e-mobility thermal runaway incidents on public transportation networks in cities, including New York City, Toronto and Madrid,” said Adam Barowy. “Our hope is that by understanding the hazard in one setting, we can apply our insights in other similar settings and prevent dangerous situations in the future.”
The report comes amid growing adoption of electric micromobility devices as commuters increasingly use e-bikes and scooters for first- and last-mile transportation.
Researchers outlined several recommendations aimed at improving passenger railcar safety during battery fire incidents. These include physical modifications to railcar layouts to separate device storage from passenger seating areas, requiring safety-certified devices on board, limiting the size of permitted e-mobility devices and designating specific storage areas.
Additional recommendations include lithium-ion battery-specific training for transit staff and improved public education to help passengers understand and reduce fire risks before boarding.
The Fire Safety Research Institute said it continues to focus on understanding how lithium-ion batteries in e-mobility devices and electric vehicles alter fire conditions, with the goal of helping emergency responders mitigate hazards safely while improving public awareness of battery-related risks.
