Research advice for cars caught in bushfires

CSIRO researchers led a groundbreaking study into the survivability of cars trapped in firestorms.

• 13 February 2009 | Updated 14 October 2011

• Groundbreaking study
• Background 
• Research
• New advice

Groundbreaking study

CSIRO researchers, working with the Bushfire Cooperative Research Centre (CRC), led a groundbreaking study into the survivability of cars trapped in firestorms.

Initiated by the NSW Rural Fire Service, the project evaluated the maximum heat load that a vehicle could face while remaining a safe haven for its occupants, both in terms of the air temperature and the air quality inside the vehicle.

This research has been used by the Australasian Fire Authorities Council (AFAC), the peak body for the fire and emergency services, to refine the guidance for people in vehicles during bushfires.

Background

Preventable death of people caught in vehicles during bushfires in Australia is a long running issue.

Previous guidelines for people trapped in these situations were based on evidence assembled from earlier tragedies, the observations of emergency service workers, and from limited tests on vehicles in the 1960s.

Although fundamentally sound, there were uncertainties about the construction and materials of modern vehicles, and the influence of protective actions taken by occupants.

Research

This led CSIRO scientists to test seven used cars at the NSW Rural Fire Service’s Hot Training Centre at Mogo.

The two-wheel-drive sedans, which ranged in size, age and make, and were donated by the NRMA, were subjected to burnover conditions with a gas flame front simulator.

Each car was fully instrumented with sensors to monitor for air toxics and heat levels at many points inside the vehicle including above and below the window height, front and rear seats and, above and beneath a woollen blanket.

Comparisons were made between having the air conditioner on or off, and by facing the car forwards, side-on or backing to the flames.

New advice

This research shows that sheltering inside a vehicle is a high risk strategy and that it is highly unlikely that a person will survive in all but the mildest circumstances.

Whilst sheltering inside a vehicle offers a slightly higher chance of survival than being caught in the open, the current policy of preparing your home, and deciding early whether you stay or go, is a much safer option.

The research made several key observations:

• Using a woollen blanket for shelter in either the front or rear foot-well of a vehicle is the most effective strategy to reduce exposure to both toxic gases and high temperatures
• Facing the front of the car towards the approaching fire was better than side or rear orientation
• Direct flame contact from either the passing fire front or from burning ground fuels makes the vehicle almost immediately untenable for occupants
• Testing under a wide range of conditions (slow/fast burn, front/rear/side orientation, etc) found that the rise in air toxics inside the vehicle was the main reason the car became unsuitable for its occupants
• Thermoplastic body parts and the structural design features of different vehicles contributed to the varied performance of cars in burnover conditions with the more recent models performing worst
• Operating an air conditioning system in recirculation mode reduces temperature exposure in all but extreme conditions and may add to your comfort in the early stages of exposure. However, air conditioning will not increase your chances of survival, on or off.

Read more about CSIRO’s work in bushfire research.