Reverse 911 as a Complementary Evacuation Warning System

Abstract

This study investigates the effectiveness of Reverse 911 warning systems compared with other evacuation warning sources. This study also investigates the impact of individual differences on evacuation behavior, and presents a regression model of evacuation behavior on the basis of empirical data. A 57 question survey was administered by telephone to people who had been affected by the 2007 San Diego wildfires, with 1020 usable responses (8.4% response rate). By signal detection theory, Reverse 911 warnings had the best performance compared with other evacuation warning sources, as indicated by the high influence rating (0.66) and hit rate (1.00). People who received the Reverse 911 warning also had a significantly higher rate of evacuation (0.80), as did those who received warnings from more than one source (0.78). Regression analysis shows that the Reverse 911 warning was critical in predicting whether an individual evacuated. Demographic factors, including knowledge and experience with previous wildfires, also played a significant role in evacuation rates, and therefore must be considered when designing a warning system.