Travel time reliability during evacuation

Abstract

Earlier studies have shown that driving behavior differs strongly in emergency conditions compared with behavior in normal traffic conditions. In this paper, these findings are followed up with an investigation of how these differences in driving behavior affect travel time reliability. In particular, the focus is on the effect of relatively strong heterogeneity in driving behavior. The microscopic simulation framework S-PARAMICS is adapted accordingly and applied to the emergency evacuation network of the Dutch city of Almere. This experimental setup allows a structured and in-depth analysis of the relationship between a number of driving behavior parameters and the emergent travel time reliability. The main findings from this study are thus insightful and directly applicable to evacuation planning and management studies. For instance, it is found that although a reduction in drivers’ mean time headway and minimum gap acceptance typically improves the overall evacuation time, travel times are simultaneously less reliable. Also, the reliability of travel times decreases over time and results in much less reliable travel times for those travelers who depart later. And finally, in general, heterogeneity in driving behavior strongly reduces travel time reliability.