One of the fires on a Bluebus in Paris, in April 2022 / Video surveillance capture.
A report analyzes the causes of the two sudden fires of electric buses in Paris, which occurred in 2022. The batteries located on the roofs caught fire suddenly, without causing any casualties. Following these disasters which the firefighters had difficulty controlling, a national investigation office published recommendations.
The Land Transport Accident Investigation Office (BEA-TT) has published a detailed report on the fires of two electric buses that occurred on April 4 and 29, 2022 in Paris. These incidents, although without serious human consequences, raise important questions about the safety of electric vehicles and their regulation.
The context of the incidents
Both fires involved Bluebus 12m-IT3s equipped with 63 kilowatt-hour (kWh) lithium-metal-polymer (LMP) batteries. The first occurred in full traffic at Maubert-Mutualité, where one of the burning batteries fell from the roof, while the second occurred at the François Mitterrand library stop, with several explosions. In both cases, the conflagration was surprisingly rapid, reaching temperatures high enough to melt vehicle roofs and spray molten metal. Investigations attribute these fires to an intercellular short circuit causing thermal runaway within the batteries, a defect linked to the manufacturing process in a Canadian BlueSolutions factory.
The emergency interventions highlighted, according to the conclusions of the report, a “major difficulty, namely that it is almost impossible to turn off quickly and completely” fires involving solid electrolyte batteries, despite rapid response times. These fires, accompanied by toxic fumes and dangerous projections, pose considerable risks to passengers, responders and the environment.
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Recommendations to prevent future incidents
The report identifies several areas for improvement and makes recommendations for manufacturers and authorities:
➡️ Strengthening alarms: Bluebus is invited to anticipate the application of amendments to UN Regulation No. 100 by lowering the thresholds for detecting failures in battery management systems.
➡️ Revision of international standards: the DGEC must initiate discussions with the UN to adapt fire resistance tests to all battery technologies.
➡️ Improvement of materials: Bluebus must strengthen the thermal protection of roofs and limit projections of molten metal to secure evacuations.
➡️ Data recording: Manufacturers are encouraged to store vehicle data to facilitate incident analysis.
➡️Fire research: the DGSCGC must coordinate a national reflection to improve the means of fighting fires of innovative vehicles.
One of the highlights of the report is the need to extend the European eCall regulation to all categories of motor vehicles. This device, which informs emergency services of the type of propulsion in the event of an accident, is considered essential for rapid and appropriate intervention.
As public transport massively turns to electric technologies to reduce its carbon footprint, these incidents highlight the importance of not neglecting safety. By integrating these recommendations, Bluebus and the authorities will have the opportunity to strengthen public confidence in new mobility.
