Journal of the Society of Disaster Information ISSN:1976-2208(Print) 2671-5287(Online) 한국재난정보학회논문집

Purpose: This study aims to analyze the thermal runaway phenomenon of lithium-ion batteries—specifically from personal mobility (PM) devices—on subway platforms and evaluate the physical vulnerabilities of underground environments. It further develops scenario-based response systems and evacuation mitigation measures to enhance public safety. Method: Existing railway accident databases and the Daegu subway fire case were analyzed. Variables such as fire scale, ignition location, air flow, and ventilation characteristics were established. Through this, the study examined the fatal impact of environmental changes in underground spaces, including the rapid spread of toxic gases and the reduction in visibility during lithium-ion battery fires. Result: Analysis of the thermal runaway stages confirmed that the spread of toxic gases accelerates significantly within approximately 2 to 5 minutes of fire onset as thermal transition between battery cells begins. In particular, the sharp decline in visibility caused by dense smoke makes self-evacuation for passengers nearly impossible, highlighting the limitations of the golden time and the necessity for an initial response system faster than that for conventional fires. Conclusion: Given the unique risks of lithium-ion battery fires, urgent technical enhancements are required, such as the introduction of early off-gas detectors and the expansion of Class D fire extinguishers. Additionally, it is essential to refine stage-specific emergency response manuals to secure the “30-minute golden time” for passenger safety in subway environments.