Transportation Vulnerability Analysis for Wildfire Evacuations

Abstract

Wildfires are a natural part of Canadian ecosystems, but sometimes pose a threat to people. In Canada, when public safety is threatened by a wildfire encroaching into the wildland-urban interface (WUI), local authorities will typically recommend and lead evacuation of the area. During evacuations, roadway egress capacity has an important influence on evacuation efficacy. If the fire spreads quickly toward the community and egress capacity is insufficient, public safety can be compromised. We identify communities in Alberta (a province in western Canada) that are vulnerable to wildfire due to the configuration of the transportation network in relation to surrounding wildfire potential. Based on the existing literature, we first used metrics applied in Geographic Information Systems (i.e., GIS) to identify communities that are vulnerable for wildfire evacuation due to the geometric layout of their surrounding road network. Then to perform our analysis, 21 potentially vulnerable communities were selected based on expert input. We plotted fire hazard and transportation facility capacities for each community, and coupled and compared estimated fire travel times and evacuation travel times in a directional, scenario-based approach, to understand the potential for community egress against fire encroachment. Our results show that some communities (mainly within the boreal forest and Rocky Mountain foothills) have egress routes highly exposed to potential fire. Our findings also indicate that evacuation timing for some larger communities may be considered for further investigations, given relationships between estimated fire travel times and evacuation times. This work contributes an interdisciplinary assessment of community directional vulnerabilities for wildfire evacuation, bringing together wildland fire science and transportation engineering. To bridge research and practice, the results are presented in an interactive online map, and can be used to inform evacuation preparedness planning and proactive mitigation efforts.