Wildland firefighter entrapment avoidance: modelling evacuation triggers

Wildland firefighters are often called on to make tactical decisions under stressful conditions in order to suppress a fire. These decisions can be hindered by human factors such as insufficient knowledge of surroundings and conditions, lack of experience, overextension of resources or loss of situational awareness. One potential tool for assisting fire managers in situations where human factors can hinder decision-making is the Wildland-Urban Interface Evacuation (WUIVAC) model, which models fire minimum travel times to create geographic trigger buffers for evacuation recommendations. Utilising multiple combinations of escape routes and fire environment inputs based on the 2007 Zaca fire in California, USA, we created trigger buffers for firefighter evacuations on foot, by engine and by heavy mechanised equipment (i.e. bulldozer). Our primary objective was to examine trigger buffer sensitivity to evacuation mode and expected weather and fuel conditions. Evacuation travel time was the most important factor for determining the size and extent of modelled trigger buffers. For the examined scenarios, we show that WUIVAC can provide analytically driven, physically based triggers that can assist in entrapment avoidance and ultimately contribute to firefighter safety.