From Normal Operation to Evacuation: Single-Vehicle Safety under Adverse Weather, Topographic, and Operational Conditions

Abstract

The negative effects of weather (e.g., strong winds, snow, and icy rain) on the safety of vehicles have been recognized and reported upon for some time worldwide. As an important category of vehicle accidents, the single-vehicle noncollision accident has not been studied sufficiently under adverse environmental and topographic conditions. In the United States, strong wind, together with other adverse weather and topographic conditions, has been blamed for many single-vehicle accidents every year, especially those involving trucks. Vehicle safety not only threatens people's lives during normal operations, but may even put many people in miserable situations when an emergency evacuation is interrupted by frequent accidents on key routes. As a result, the safety of many people who are delayed in congestion on evacuation routes may be jeopardized. The reasons that cause single-vehicle accidents can be very complicated: from a single primary reason such as strong wind gusts to the combination of several reasons such as weather conditions, vehicle conditions, road surface conditions, driver operational errors, etc. This study seeks to investigate the safety of vehicles during normal operations as well as emergencies through replicating the natural environments. It starts with a brief overview of single-vehicle accidents caused by environmental and topographic conditions around the United States in normal operations, followed by discussions about the current challenges existing in the evacuation practices. An attempt is then made to model the complicated weather, road surface, and driver operational process, such as rain, snow, camber, grade, and acceleration/deceleration as well as steering processes. With the proposed accident assessment framework, the accident-related response is studied and accident risks are assessed for vehicles. The study may also provide a useful basis for traffic designs on highways with complicated topographic and weather conditions and optimization of evacuation routes and strategy with minimized single-vehicle accident risks.