Theoretical vs. Empirical Classification and Prediction of Congested Traffic States

TL;DR

This paper develops a theoretical framework for classifying and predicting congested traffic states based on traffic flow models, and provides empirical evidence for a phase diagram of traffic phases, including new pattern types.

Contribution

It introduces a phase diagram of traffic states derived from instability diagrams, highlighting new widening synchronized patterns and effects of on- and off-ramps.

Findings

Existence of widening synchronized patterns within metastable regimes

Empirical support for a phase diagram of traffic states

Impact of ramp configurations on traffic patterns

Abstract

Starting from the instability diagram of a traffic flow model, we derive conditions for the occurrence of congested traffic states, their appearance, their spreading in space and time, and the related increase in travel times. We discuss the terminology of traffic phases and give empirical evidence for the existence of a phase diagram of traffic states. In contrast to previously presented phase diagrams, it is shown that "widening synchronized patterns" are possible, if the maximum flow is located inside of a metastable density regime. Moreover, for various kinds of traffic models with different instability diagrams it is discussed, how the related phase diagrams are expected to approximately look like. Apart from this, it is pointed out that combinations of on- and off-ramps create different patterns than a single, isolated on-ramp.