Is Your Commuter Rail Ready for an E-Scooter Fire?

E-scooters and e-bikes are showing up on commuter trains every day, but the fire hazards they present are not yet addressed by many rail inspection programs. New research from UL Research Institutes (ULRI) documents what happens when the lithium-ion batteries powering these vehicles fail aboard a passenger railcar. The results are a clear signal that fire marshals and code authorities overseeing rail facilities and station design need to understand and consider appropriate mitigation measures.

Electric micromobility vehicles (EMVs) — a category that includes e-scooters, e-bikes, seated scooters, hoverboards and similar devices — rely on lithium-ion batteries (LiBs) for power. LiBs are reliable under normal conditions, but they can fail through a process called thermal runaway, in which internal heat builds faster than the battery can release it. This chain reaction produces intense heat, flammable gas and typically fire. The most common triggers are physical damage to the battery, overcharging (e.g., through faults in the battery management system) or overheating.

In residential settings, LiB fires from EMVs have already caused deaths. New York City, London, Ottawa and other cities have documented fatal and injury-causing fires from e-scooters and e-bikes in apartments and hallways. The enclosed space of a passenger railcar raises the stakes further: more occupants, limited exits, typically no automatic fire suppression system and a train that takes time to stop.

ULRI researchers conducted four fire experiments inside a 72-seat single-level commuter railcar, forcing thermal runaway in three types of EMVs: a standing e-scooter stored in an overhead luggage rack, an e-bike hung on a designated bicycle hook and two seated e-scooters parked in the wheelchair area.

The findings across all four experiments point to a concerning pattern:

• Once a smoking battery ignited, smoke spread to the far end of the railcar in as little as 26 seconds and no more than 109 seconds across all four experiments. Notably, smoke moved slowly before ignition; rather, it was sustained flaming that dramatically accelerated its movement. This means that by the time passengers could confirm something was wrong, smoke was spreading rapidly.
• Visibility was completely lost between 1 minute and 48 seconds and 4 minutes and 6 seconds after ignition, with a median of about 3 minutes and 12 seconds. Reduced visibility is known to slow evacuation because passengers may have difficulty moving through the railcar and identifying exit routes.[1]
• Smoke conditions became untenable between 3 minutes and 37 seconds and 7 minutes and 8 seconds after ignition, with a median of about 4 minutes and 54 seconds, creating conditions dangerous enough to incapacitate passengers.
• Passengers within 10 feet of the burning vehicle were at risk of serious burns from the initial fireball and fire plume within 20 to 60 seconds.

For code authorities overseeing passenger rail facilities, transit stations or other related occupancies, these findings have concrete implications. This research identifies several considerations that point to where inspection programs and policies may need to evolve:

• Avoid storing EMVs in the first and last railcars. An EMV stored in these railcars creates the most dangerous scenario, as it can block the only exit toward an adjacent car while passengers are trapped at the far end of a train. Inspectors reviewing railcar configurations or transit facility layouts should consider whether EMV storage policies address this risk.
• Separate EMV storage from the passenger cabin. Using noncombustible materials and designed venting in designated areas on the train could significantly limit fire growth and smoke exposure. The report draws a parallel to battery enclosure designs used in commercial aviation that incorporate pressure-relief venting to help manage gases released during a battery failure.
• Certification matters. A pre-boarding inspection and registration program for EMVs tested by a Nationally Recognized Testing Laboratory to UL 2849, the Standard for Electrical Systems for eBikes, and UL 2271, the Standard for Batteries for Use in Light Electric Vehicle (LEV) Applications, is one practical step transit authorities can consider.
• Early detection and clear notification are critical. Given how quickly conditions became dangerous in these experiments, early detection and clear, instructive announcements directing passengers to evacuate immediately — without stopping to gather belongings — could be the difference between a safe exit and a life-threatening smoke exposure.

This research doesn’t suggest that e-scooters and e-bikes should be banned from trains. However, experimental data demonstrate that the current approach to managing them creates measurable safety risks for passengers. The gap between how fast these fires grow and how long it takes to evacuate a railcar is narrow — and in less-than-ideal conditions, the data suggests passengers may already be exiting through untenable conditions.

Fire marshals, transit facility inspectors and others with jurisdictional authority over passenger rail should bring this data into policy and code discussions and inspection checklists before incidents force the issue.

The full ULRI report, Recommendations to Improve Passenger Railcar Safety During Electric Micromobility Vehicle Fires, is available at https://doi.org/10.60752/102376.32136697.

For resources on lithium-ion battery fire hazards and public safety education, visit www.batteryfiresafety.org.