Time-Dependent Route Choice in Hurricane Evacuation

Abstract

In this research, the factors affecting route choice in hurricane evacuation are investigated. Two hypotheses are tested. First, it is hypothesized that contrary to common practice where travel time is considered the sole or main determinant of route choice, other variables such as familiarity with the route, availability of fuel and shelter, road type, and accessibility of the route have an effect on an evacuees’ route choice as well. The second hypothesis is that as time passes and storm conditions change, the impact each variable has on route choice changes. That is, it is hypothesized that the importance evacuees assign to the factors determining route choice is not static but varies with time. The logit structure was used for modeling the choice process and stated choice data previously collected from the New Orleans area on hypothetical storms was used to calibrate the model. The study found that accessibility to a route, familiarity with the route, road type, length of a route, and availability of services (gas stations and hotels) had an effect on evacuation route choice. The magnitude of the coefficients of perceived service, accessibility, and distance differed among those evacuating in the first half of the evacuation period versus those that evacuated in the second half, but coefficients of road type were not significantly different between the two time intervals. Observed traffic count data from hurricane Katrina evacuation were used to validate the model. Comparison of traffic volumes predicted by the model with actual traffic volumes from hurricane Katrina shows error percentages of 17.5, 0.01, and 28% of error for volumes on I-10, I-55, and US-61 respectively.