Microscopic driving theory with oscillatory congested states: model and empirical verification

TL;DR

This paper introduces a new microscopic traffic model that explains oscillatory congested states without steady-state solutions, validated by empirical data and outperforming previous models.

Contribution

The study proposes a cellular automaton model capturing oscillatory congested states, challenging existing theories with a new dynamic approach validated by empirical data.

Findings

Empirical data show a linear gap-speed relationship when speed difference is near zero.

Vehicles tend to accelerate or decelerate around a desired space gap.

The new model reproduces empirical phenomena and outperforms previous models in calibration and validation.

Abstract

The essential distinction between the Fundamental Diagram Approach (FDA) and Kerner's Three- Phase Theory (KTPT) is the existence of a unique gap-speed (or flow-density) relationship in the former class. In order to verify this relationship, empirical data are analyzed with the following findings: (1) linear relationship between the actual space gap and speed can be identified when the speed difference between vehicles approximates zero; (2) vehicles accelerate or decelerate around the desired space gap most of the time. To explain these phenomena, we propose that, in congested traffic flow, the space gap between two vehicles will oscillate around the desired space gap in the deterministic limit. This assumption is formulated in terms of a cellular automaton. In contrast to FDA and KTPT, the new model does not have any congested steady-state solution. Simulations under periodic and open boundary conditions reproduce the empirical findings of KTPT. Calibrating and validating the model to detector data produces results that are better than that of previous studies.