Hysteresis Phenomena Behind Freeway Bottlenecks

Abstract

This study aims to improve the understanding of hysteresis phenomena in Network Macroscopic Fundamental Diagrams (NMFDs) and Network Exit Functions (NEFs) during rush hours. We employ the LWR model based on trapezoidal boundary conditions upstream of a discontinuous bottleneck to analyze the time-dependent relationship between traffic accumulation and trip completion rate and average flow in urban traffic networks. The methodology includes a theoretical analysis supported by numerical experiments to approximate rush hour-specific traffic behavior. The study links the relationship between inhomogeneous vehicle distribution in traffic networks and hysteresis loops in MFD relationships to measurable traffic flow quantities for the first time. The main conclusions indicate the presence of hysteresis loops in flow- and outflow-MFDs. The study contributes to traffic flow modeling by offering insights into the effects of congestion distribution and network topology on traffic performance.