An empirically based approach to defining wildland firefighter safety and survival zone separation distances

Abstract

Abstract. Wildland firefighters in the US are mandated to identify areas that provide adequate separation between themselves and the flames (i.e. safety zones) to reduce the risk of burn injury. This study presents empirical models that estimate the distance from flames that would result in a low probability (1 or 5%) of either fatal or non-fatal injuries. The significant variables for the fatal injury model were fire shelter use, slope steepness and flame height. The separation distances needed to ensure no more than a 1 or 5% probability of fatal injury, without the use of a fire shelter, for slopes less than 25% were 20 to 50 m for flame heights less than 10 m, and 1 to 4 times the flame height for flames taller than 10 m. The non-fatal injury model significant variables were fire shelter use, vehicle use and fuel type. At the 1 and 5% probability thresholds for a non-fatal injury, without the use of a fire shelter, the separation distances were 1 to 2, 6 to 7, and 12 to 16 times greater than the current safety zone guideline (i.e. 4 times the flame height) for timber, brush and grass fuel types respectively.Additional keywords: fire behaviour, firefighter entrapment, flame height, safe separation distance.

Wildfire Response Performance Measurement: Current and Future Directions

“…The fourth recommendation is to focus more directly on responder safety and exposure. Whereas we began from the notion of quantifying effectiveness in order to reduce instances of ineffective resource use (and thereby reduce unnecessary exposure), KPIs could be explicitly designed around factors such as safety zones and egress routes [51][52][53]. As an example, in-depth post-fire analysis could evaluate the frequency with which safety zones were pre-identified and determined suitable per new standards.…”

Fuel and topographic influences on wildland firefighter burnover fatalities in Southern California

“…Several characteristics associated with many of the plants that compose Chaparral have been argued to contribute to their overall flammability, including high surface area to volume ratio (Countryman and Philpot 1970), low fuel moisture (Dennison and Moritz 2009) and high extractive content (Philpot 1969). Fuel types composed primarily of shrubs have also been shown to be the most dangerous in terms of the likelihood of an injury for entrapped firefighters (Page and Butler 2017).…”

“…Recent reviews of mostly agency-produced accident investigation reports indicate that the actual locations of fatal and nearmiss incidents for firefighters are rarely directly reported in the US, especially for older incidents, e.g. pre-1990s (Page and Butler 2017). Although the MaxEnt approach may only require as few as five occurrence locations (Pearson et al 2007), thirty or more are usually recommended to produce a more accurate model (Wisz et al 2008).…”

“…The rapid increase in fire behaviour associated with eruptive conditions often surprises firefighters, making previously identified escape routes, escape times and safety zones inadequate, which can sometimes result in death or serious injury (Rothermel 1993;Butler et al 1998;Cheney et al 2001;Viegas and Simeoni 2011). Recent research has also shown that firefighters who are entrapped by a fire on steep slopes have a significantly lower likelihood of survival than firefighters entrapped on flatter terrain (Page and Butler 2017).…”

Toward safer firefighting strategies and tactics

“…Therefore firefighters face different types of mitigation difficulties (Lahaye et al 2014). They also face different risks of entrapment (Page and Butler 2017;Lahaye et al 2018a).…”