Switch between critical percolation modes in city traffic dynamics

TL;DR

This study reveals that city traffic networks switch between two critical percolation modes under different traffic conditions, resembling small world and 2D lattice behaviors, which impacts traffic resilience.

Contribution

It uncovers the dynamic switching of percolation modes in city traffic networks driven by traffic conditions, linking network topology and traffic dynamics.

Findings

Traffic during nonrush hours behaves like small world networks.

Rush hour traffic exhibits 2D lattice percolation characteristics.

Switching modes are driven by effective long-range connections during different times.

Abstract

Percolation transition is widely observed in networks ranging from biology to engineering. While much attention has been paid to network topologies, studies rarely focus on critical percolation phenomena driven by network dynamics. Using extensive real data, we study the critical percolation properties in city traffic dynamics. Our results suggest that two modes of different critical percolation behaviors are switching in the same network topology under different traffic dynamics. One mode of city traffic (during nonrush hours or days off) has similar critical percolation characteristics as small world networks, while the other mode (during rush hours on working days) tends to behave as a 2D lattice. This switching behavior can be understood by the fact that the high-speed urban roads during nonrush hours or days off (that are congested during rush hours) represent effective long-range connections, like in small world networks. Our results might be useful for understanding and improving traffic resilience.