Risk Reduction by Urban Evacuation: State of the Art on Traffic Assignment Models

Systematic studies about risk reduction by urban evacuation started in early 2000’s, mainly after the 9/11 attack and the Katrina hurricane. Today, new frontiers opened by the next-generation of Transportation System Models (TSMs) request further developments of research. One of the research lines concerns the development of traffic assignment models able to estimate the performances and flows that arise from the interaction between the users’ choices (e.g., evacuees) and the performance of transport infrastructures and services in emergency conditions. The work deals with the state of art about publications on traffic assignment models to support risk reduction by urban evacuation. The existing traffic assignment models are classified according to the theoretical background, the static or dynamic nature, the equilibrium or network loading approach. The results of the work concern a state of the art on traffic assignment models for risk reduction by urban evacuation. The current approaches of traffic assignment models in risk reduction by urban evacuation are analyzed and compared. The findings allow to pinpoint the main trends, gaps, and future directions in the examined research field. The main modeling advancements concerning the dynamics of traffic assignment models are made possible due to the massive adoption of e-ICTs. The conclusions of the work concern the challenges that need to be addressed for the development of traffic assignment models in support of the assessment of risk reduction by urban evacuation.