Phase Diagram of Traffic States in the Presence of Inhomogeneities

TL;DR

This paper develops a phase diagram illustrating various congested traffic states caused by inhomogeneities like ramps, supported by simulations aligning with empirical data, and suggests universality across models.

Contribution

It introduces a universal phase diagram for traffic states triggered by inhomogeneities, validated by nonlocal gas-kinetic-based simulations and empirical data.

Findings

Different congested traffic states are triggered by inhomogeneities.

Simulation results agree with empirical observations.

The phase diagram is universal across various traffic models.

Abstract

We present a phase diagram of the different kinds of congested traffic that are triggered by disturbances when passing ramps or other spatial inhomogeneities of a freeway. The simulation results obtained by the nonlocal, gas-kinetic-based traffic model are in good agreement with empirical findigs. They allow to understand the observed trasitions between free and various kinds of congested traffic, among them localized clusters, stop-and-go waves, and different types of ``synchronized'' traffic. The proposed conditions for the existence of these states suggest that the phase diagram is universal for a class of different microscopic and macroscopic traffic models.