Modeling a contraflow evacuation method for tropical cyclone evacuations in Nueces County, Texas

Each year in the USA, hurricanes threaten millions of coastal residents. These storms have the potential to devastate areas with heavy rain, damaging winds, severe flooding and strong storm surge. These geophysical phenomena are particularly dangerous along the low-lying coastal zones of the Gulf of Mexico and the Atlantic coast. The threat of these storms prompts many coastal areas to create disaster plans which often include evacuation strategies to help guide area residents to safety before a storm makes landfall. This research examined the prescribed contraflow evacuation plan for Nueces County, Texas in an effort to model what an evacuation may look like during a major tropical cyclone landfall like the near miss of Hurricane Harvey during the 2017 hurricane season. ArcGIS was used to route thirteen potential evacuation routes out of Nueces County. These routes were then used to simulate evacuations under “optimal,” “expected” and “worst-case” scenarios. It was determined that, while contraflow evacuations can cause severe traffic congestion and lead to long evacuation times, they have the potential to effectively evacuate an area under both “optimal” and “expected” conditions. The results of this analysis add to the growing body of research focused on leveraging geographic information systems to improve local-scale evacuation planning.