Burning electronic cars: Austrian tunnels tolerate heat

The heat release of the electric vehicles burning in the tunnel, which was measured by more than 30 sensors, was 6-7 MW, which is slightly higher than that of the comparator diesel vehicles (5 MW). However, according to experts, this does not entail any new risks or dangers. In comparison, the fire load of a conventional truck is about 30 MW. “When electric cars fire, they get a little hot in the tunnel, but it’s basically not more dangerous. The temperatures measured in the escape zone are below 60 degrees Celsius max for all fire tests. That’s not a nice temperature, but Sturm summed up in his summary that Escape and firefighting operations are still going on.”

The escape routes are not affected by fire gases

Gases and heavy metals generated during fires were collected and measured: here, higher amounts of hydrogen fluoride and carbon monoxide in particular are considered critically. “However, the thermally induced smoke gas layers in the tunnel mean that these highly concentrated fire gases mainly collect in the upper areas of the tunnel and thus outside the human-related area. This means that escape routes are not affected,” the statement explained. Technician, himself concerned with air quality in tunnels for over 30 years.

According to Sturm, ventilation systems have a large share of the relatively low risk in road tunnels: “They are not found in parking garages, for example, or at least not to the same degree that they urgently need to be closely examined. The researcher in Graz warned that the results of The measurement we came up with anyway suggests that there are serious risks.”

According to experts, the type of driving of a burning vehicle does not make any relevant difference in terms of damage to the structure and materials of the tunnel: damage to concrete due to shards is expected in both classes of vehicles in the case of commercial vehicle fires. The damage pattern is almost the same.

Extinguishing with water

Among the methods of extinguishing, fighting fires with water was the best. “However, experience shows that with lithium-ion batteries, successful extinguishing occurs only when the water reaches the inside of the battery,” says Stefan Krausbar of the Austrian Federal Fire Union. In any case, the extinguishing period and the need for extinguishing agents will increase. The use of fire spears has proven to be effective, but emergency services must be specially trained in this. After use, the extinguishing water was heavily contaminated with heavy metals – especially nickel. This increases disposal costs, explained Günter Rattei of Asfinag.

Project Director Sturm emphasized the importance of further investigation: The range of fire effects for battery-powered commercial vehicles – buses and trucks – was only scaled using numerical simulations based on assumptions about fire development, duration and pollutant release. Thus, comprehensive fire experiments in large-scale experiments will greatly improve the quality of information. The same applies to the specified danger situation in the case of fires of electronic vehicles in parking garages. “With all the joy about the advancement of alternative driving systems, the ‘homework’ related to safety should not be neglected,” Sturm appealed for legislation and research funding.