Abstract: The increase in the number of urban electric vehicles brings new challenges to urban traffic tunnel fire safety belts. The paper first summarizes the scientific and key technical issues related to the study of electric vehicle fires in tunnels, and then presents research findings in areas such as the causes of electric vehicle fires and research methodologies, thermal characteristics of fire combustion, characteristics of fire combustion products, etc. It also examines the impact of the narrow and confined environment of tunnels on the development of electric vehicle fires and discusses fire rescue strategies for electric vehicle fires in urban traffic tunnels. According to current fire safety standards and tunnel fire design guidelines, the key points for improving the design of fire protection systems in traffic tunnels to address electric vehicle fires are discussed. Research indicates that fire incidents involving new energy vehicles are more complex compared to those involving conventional fuel-powered vehicles. This complexity is primarily manifested in unstable battery ignition sources, prolonged durations, peak heat release rates, peak temperatures, and the risk of electric vehicle electrification. Moreover, there remains a lack of systematic studies on the influence of confined tunnel spaces on battery combustion characteristics, the characteristics of plumes generated by electric vehicle fires, as well as the spread and control of toxic smoke. The findings of this study can provide valuable insights for the design of fire protection systems in urban traffic tunnels, ensuring safe operations, and formulating emergency response plans.

Key words: electric vehicle, fire, heat release rate, thermal runaway, urban traffic tunnel