Traffic Performance Indicators for Evacuation: The Case Study of the 2020 Silverado Wildfire

Abstract This study aims to facilitate the study of traffic dynamics in wildfire evacuation scenarios. To do so, it defines a set of traffic performance indicators to investigate traffic dynamics before and during wildfire evacuation events. These indicators include the following: system efficiency, travel time ratio, level of service, and jam time. To highlight the benefits and effectiveness of using these indicators, we demonstrated their application through the context of the 2020 Silverado fire in California, USA. In total, 66,924 traffic data points from 18 locations were obtained through the publicly available dataset of the California Department of Transportation. Results indicate a 7.5 km/h speed reduction during evacuation compared to routine conditions. In addition, traffic performance indicators confirmed that evacuation conditions may increase the times needed to reach destinations. This paper also demonstrates the need for using dedicated relationships for wildfire evacuation for developing, calibrating, and validating traffic modeling tools.