Contents lists available at ScienceDirect Transportation Research Part D journal homepage: www.elsevier.com/locate/trd Assessment of post-disaster reentry traffic in megaregions using agent-based simulation Zhao Zhang a, ⁎ , Brian Wolshon b , Nelida Herrera b , Scott Parr c a School of Transportation Science and Engineering, Beihang University, Beijing, China b Gulf Coast Research Center for Evacuation and Transportation Resiliency, Louisiana State University, LA, United States c Embry-Riddle Aeronautical University, FL, United States ARTICLE INFO Keywords: Megaregions Post-disaster Reentry assessment Agent based simulation Heterogeneity ABSTRACT Transportation personnel, assets, and systems play important roles during emergencies. Of par- ticular note is the critical function of road networks as lifelines for evacuations, then, after such events, to facilitate the rapid inflow of support personnel and resources needed to assess and repair damage. They also provide access for the safe and rapid return of evacuees. Despite the importance of reentry and repopulation, the role of transportation systems for them has been a relatively lightly researched topic. This paper describes research to analyze the traffic processes associated with post-evacuation reentry and its associated travel time and delay. To examine the most extreme of conditions; this effort also focused on repopulation and reentry after mass evacuations in megaregions. Among the findings of this work were that, as expected, reentry traffic processes generally behave similar to, but in the reverse direction, of evacuations. However, contrary to commonly held belief, they are not identically opposite. Rather, network performance during reentry may often be better than that of evacuation. Another broad finding of the research was that the spatial heterogeneity of traffic distribution across available roadways is a primary factor in determining network performance, meaning the more uniform the spread of on all links, the more efficient the network will operate. A third significant finding of this re- search was also the importance of the temporal spreading of returnee departure times on network efficiency. 1. Introduction Transportation systems serve as vital lifelines to preserve health, safety, and property during times of disaster and emergency. Among the most important ways that transportation systems, personnel, and infrastructure support emergency preparedness is through evacuations. The management and operation of infrastructure and transit assets during such scenarios represent one of the most visible and direct contributions of transportation before disasters and, undoubtedly, save the lives of thousands annually throughout the world. However, just as important as the role that transportation plays before disasters is role that it plays after. Transportation is a also key component in recovery because it underpins the restoration of communities and helps to minimize economic impacts. After disasters, transportation networks provide critical conduits for the safe and rapid return of evacuees. It is thought that the faster that people can return to their homes, jobs, and schools, the faster communities will recovery and less adverse the effects of a https://doi.org/10.1016/j.trd.2019.06.010 Received 27 March 2019; Received in revised form 26 June 2019; Accepted 26 June 2019 ⁎ Corresponding author. E-mail address: zhaozhang@buaa.edu.cn (Z. Zhang). Transportation Research Part D 73 (2019) 307–317 1361-9209/ © 2019 Elsevier Ltd. All rights reserved. T