ENGLISH ABSTRACT: Train fires continue to pose a significant threat both internationally and in South Africa, particularly with the increasing prevalence of emerging hazards such as lithium-ion battery devices carried by passengers. With the introduction of the new X’Trapolis Mega fleet, it is essential to evaluate fire safety performance when exposed to both conventional and emerging hazards to ensure sufficient time is available for safe evacuation. This study investigates fire growth and tenability conditions in a single passenger carriage through numerical modelling using Fire Dynamics Simulator (FDS). Generic material properties have been incorporated to broaden the applicability of the results and offer adaptability for future specifications. Eight fire scenarios were developed, ranging from traditional luggage fires and arson to lithium-ion powered devices such as tablets, e-bikes, and e-scooters. The models were assessed in terms of heat release rate development, flashover potential, and available safe egress time at both 1.5 m and 0.9 m above the floor level, representing typical standing and crawling breathing zones. The results demonstrate that conventional luggage fires provide up to 5 min of evacuation time, with flashover occurring after approximately 8 min. In contrast, arson resulted in untenable conditions within 30 s at 1.5 m and flashover within 5 min after ignition. Lithium-ion devices showed variable performance: small fires from devices such as e-cigarettes and tablets pose limited threat with no significant fire spread and subsequently no flashover. Larger e-mobility devices presented significant hazards, with the e-bike fire scenario resulting in impaired evacuation in less than 40 s at 1.5 m and reaching flashover in 5 min 23 s. The seated e-scooter presented the most severe scenario, with impaired evacuation in under 20 s at 1.5 m and flashover after 3 min 22 s. Overall, the study shows that while the new X’Trapolis carriage adheres to strict fire standards, both arson and large lithium-ion devices create conditions in which the safety of passengers intimate with the fire cannot be assured. Material specifications were found to effectively limit fire spread in small battery fire incidents and did not significantly influence initial life safety conditions, as tenability limits were primarily determined by the first item ignited. Passenger behaviour, including moving away from fire risks and crouching low to avoid toxic smoke, is critical for survival. Tenable conditions are also influenced by ventilation, which can help contain smoke in the carriage of origin and prolong the evacuation time for adjacent carriages. The findings underscore that life safety requires not only engineering measures but also effective operational controls, passenger management, and ventilation strategies, particularly concerning e-mobility devices.
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