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Project ResearchersOverviewThis project intends to identify the size of an area a firefighter can hunker in place and survive in a wildfire situation. Little research exists that provides firefighters this information to use when involved in a life-threatening situation. Firefighters must understand that they will be in a very uncomfortable situation, but should survive if they need to use a survival zone. BackgroundWhen avoidance tactics have failed and firefighters are unable to make it to their safety zones, what is the minimum area a firefighter can survive in when entrapped by a wildfire? Many factors are involved in determining this size: fuel type and height, protective clothing worn by the firefighter, duration of exposure, etc. Generalised rules have been established for safety zone size based on flame height, but no research has taken place to determine the minimum size an area a firefighter can use to survive an entrapment. Safety zones differ from survival zones in that they are an area a firefighter can take refuge where they are safe from the effects of the radiation. Survival zones are smaller in principle and are areas where firefighters lying prone on the ground are able to survive beyond direct flame contact and are subjected to degrees of discomfort and potential injury. Theoretical values can be calculated for fire intensity based on distance from a flame front of variable heights. Human tolerance levels (intensity levels in kW/m 2 ) are also known, but these have not been verified with field research. ean flame heights for most fuel complexes are roughly two times the height of the fuel, be it grass or forest. Using this relationship and knowing that flame height is related to fire intensity, heat flux based on distance from the flames can be estimated. Since flame temperatures and radiation characteristics are constant between fuel types (other than duration), grass fuels may be used to mimic a ‘small forest'. Working with grass fuels has many advantages such as moving equipment and the number of burns that can be undertaken within a given buring window. The distance/intensity relationship will be verified from prior modelling and fieldwork in grass fuels. This procedure will then be replicated in standing timber and potentially in other representative fuel types if appropriate sites can be indentified. Definitions: Safety Zone – an area distinguished by characteristics that provide freedom from danger, risk or injury (Beighley 1995). Or, ‘an area used for escape in the event the line is outflanked or in case a spot fire causes fuel outside the control line to render the line unsafe…areas that can be used with relative safety by firefighters and their equipment in the event of a blowup in the vicinity'. (National Wildfire Coordination Group (USDA/USDI 1995)). Survival Zone – an area of variable size based on adjacent fuel height to be used as a last resort where a firefighter can hunker in place, beyond flame reach and potentially sustain some injury, but survive the passage of a fire front (Baxter, 2007). ObjectivesThe objective of this research is to determine the minimum clearing size required to produce a reasonable chance of survival based on fuel height and human survival thresholds. Methodology
Computer modeling will be performed by the University of Alberta Mechanical Engineering Department to serve as a starting point for estimating the size of a survival zone in a grass fuel complex. This model will use known physical relationships for radiation intensity and distance and then combine this output with human tolerances (which includes protection from clothing), to calculate a starting survival zone size for testing in field conditions. This will be complemented with studies done for the US forest service on radiation only exposures in standard PPE. We will likely want to add to this as the materials used were only Nomex (standard US garb) and not necessarily what is used in Canada , A knowledge gap currently exists in understanding radiation intensity based on distance and height from a wall of flame. Our experimental survival zones will be instrumented to determine radiation values at set heights and distances from the edge of the clearings. All preliminary fieldwork will occur in grass fuels to verify the theoretical relationships at a small scale and because many replications can be performed quickly in this fuel type. Instrumental methodology will be tested in grass fuels before been used in a forest setting (where the number of replicates is low due to the amount of work involved and more factors are involved in having a successful burn). This methodology will provide data on temperature and radiation exposure near ground level where a person lying prone would be. TimelineThis is a large project requiring collaboration and the purchase of extra scientific equipment to ensure sufficient data samples within a plot are collected. Thus the cost of this project is high and the project duration is a minimum of three years. 2008 Complete literature review of intensity/distance relationship Complete literature review of human/clothing survivability Build and purchase field equipment Computer modelling simulations Find grass sites for burning Perform burning Find potential test sites Burn if possible 2009 Burn survival zone(s) 2010 Burn survival zone(s) DeliverablesThe deliverable from this project will be general guidelines based on fuel type and human thresholds. The following table is an example:
The outputs from this work will be peer reviewed due to the serious nature of the work and the potential for liability.
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Burn Injuries and Their Relation to Wild Land Fire Fighting 5/7/2010 Research update - Determining the key characteristics of a survival zone 12/2/2009 |