Urban Traffic Dynamics: A Scale-Free Network Perspective

TL;DR

This paper introduces a novel model for urban traffic dynamics using scale-free network theory, revealing phase transitions, hysteresis, and bistability in traffic flow, which differ from traditional models.

Contribution

It presents a new scale-free network-based model for urban traffic, incorporating road capacity and intersection handling, with simulation results showing complex phase transitions and flow behaviors.

Findings

Identifies a phase transition from free flow to congestion.

Discovers hysteresis indicating bistability in traffic flow.

Shows fundamental diagram differs from traditional single-lane models.

Abstract

This letter propose a new model for characterizing traffic dynamics in scale-free networks. With a replotted road map of cities with roads mapped to vertices and intersections to edges, and introducing the road capacity L and its handling ability at intersections C, the model can be applied to urban traffic system. Simulations give the overall capacity of the traffic system which is quantified by a phase transition from free flow to congestion. Moreover, we report the fundamental diagram of flow against density, in which hysteresis is found, indicating that the system is bistable in a certain range of vehicle density. In addition, the fundamental diagram is significantly different from single-lane traffic model and 2-D BML model with four states: free flow, saturated flow, bistable and jammed.