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Australian Road Research BoardAugust 10, 20221 min read

Electric Vehicle fires in tunnels

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Research is being undertaken into the safety risk of fires caused by electric vehicles (EVs) vs non-EVs in Australian road tunnels.

Senior Professional Leader, Mobility Futures, Dr Robert Kochhan, and Senior Professional Leader, Safer Smarter Infrastructure, Brendan Williams, recently participated in a vehicle fire demonstration in the Sydney Harbour Tunnel.

A car (non-EV) was put alight in the southbound tunnel, in a controlled environment about 800m from the northern entrance to the tunnel where the tunnel management office is. After an initial explosion that caused some vehicle parts such a window glass to scatter around the vehicle, the car fire started and triggered the tunnel sprinkler system which kept the fire at bay. The tunnel exhaust system was also engaged to remove harmful smoke from the tunnel. Professional fire fighters finally extinguished the fire.

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The big question is how EV fires need to be treated. Considering the big batteries of EVs and their high energy content, an EV fire can be hard to extinguish. Large volumes of water are required to suppress the battery fire. There is also a risk that the battery reignites after the fire has stopped.

Dr Robert Kochhan says that Europe’s systems set a good example for other countries with their alpine tunnels.

“We should look at Europe where testing has already been undertaken and studies are available. The general consensus is that there are no significant concerns regarding EV fires there,” Dr Kochhan said. However, more detailed research needs to be conducted to investigate the applicability of overseas findings in Australia, and additional studies and tests may need to be carried out to ensure that our tunnels are fit for the wave of EVs coming to Australia.

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Bob Allen, General Manager and current Tunnel Operator of the Sydney Harbour Tunnel also mentioned that EV-precautions regarding high voltage need to be taken. If it is unknown whether the vehicle on fire is an EV or not, the EV’s high voltage systems are a safety risk. First responders need to be aware of the vehicle technology to manage the incident appropriately and not put anyone at risk, including themselves or vehicle occupants.

Click the video below to view the video of the tunnel fire demonstration.

Click here to get in touch with Dr Robert Kochhan.

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