Fire-tested systems help crews survive truck burnovers

By Roger Nicoll, Justin Leonard

During this devastating bushfire season, media channels have shared footage of firefighters driving through raging fires. To escape the flames, firefighters have used spray systems and held up heat blankets to windows inside the cabin.

These terrifying moments when flames can overrun and burn over a fire truck are called flashover or burnover. And, while firefighters have strategies and operational procedures to minimise risk, these dangerous events still occur and can be fatal. Our research is helping firefighters survive these dire situations.

The road to crew protection from burnovers

Following some tragic burnovers in the late 1990s, the Victorian Country Fire Authority (CFA) and the New South Wales Rural Fire Service (RFS) asked for our help.

We worked with them to develop safety parameters for fire trucks and to test the effectiveness of modifications like water sprays and shielding.

We designed a series of 24 tests carried out on two fire tankers at the RFS’s Hot Test Fire Facility at Mogo in New South Wales. Our testing used a number of gas burners to simulate the approach of a bushfire front and the burnover of the fire trucks. This simulator used our detailed knowledge of fire front characteristics and behaviour to accurately recreate burnover conditions similar to a real bushfire.

The simulator subjected the fire trucks to varying fire intensities while we recorded detailed measurements of radiation, temperature and toxic gases.

New and better crew protection systems for burnovers

Data we collected during the Mogo tests informed new and better prototypes for crew protection. We tested these prototypes using worst-case burnover conditions in the simulator.

Field experiments in Tumbarumba NSW and Brucknell Park Victoria further validated the systems. These forest burnovers provided additional confidence in both the protection system design and the exposure conditions achieved in the simulator.

Since 2006, fire trucks now have key features to support safety and survival:

a ring of spray nozzles that deliver a ‘water curtain’ over the vehicles cabin

radiant heat shields or curtains for windows to block radiation from reaching the people in the cabin. These inclusions also provide an extra layer of protection if the windows break

water sprays to stop wheels and pumps catching alight

fire resistant covers for electrical, pumps, air intakes and air hoses.

Bushfire science supporting the nation

Our crew protection system testing is another example of how controlled experiments, science and innovation is helping safeguard people. The simulator has also been used to assess a wide range of other systems including houses, power poles, fences and water tanks.