A Review of Safety Measures in Battery Electric Buses

Battery electric buses (BEBs) are widely regarded as a safe and sustainable alternative to internal combustion vehicles. However, the lithium-ion batteries that power them present safety risks. This paper provides a comprehensive overview of the safety of battery electric buses, highlighting current challenges, relevant regulations and proposed solutions to enhance safety. There are significant shortcomings in the fire safety regulations for buses, especially concerning qualification methods for bus interiors. Enclosed spaces and structures represent the most critical risks for these transport systems. The presence of large vehicles, such as BEBs, in tunnels could increase the risk of transitioning from deflagration to detonation. Fires involving such vehicles produce more soot than fires from internal combustion engine buses (ICEBs) and have slightly higher toxicity levels. High-pressure water spraying systems are not yet an effective solution, as not all the heat is removed if the thermal runaway has already been triggered for several minutes, and their action remains largely limited to the outside of the battery pack. Another critical issue is cybersecurity. Managing and protecting BEBs from cyber threats is complex and requires robust strategies.