Crossover transitions in a bus-car mixed-traffic cellular automata model

TL;DR

This paper extends a cellular automata model to analyze mixed-traffic dynamics, revealing how passenger flow and bus spacing influence transitions between platooned and free-flow states.

Contribution

It introduces a modified NaSch model incorporating passenger and stop constraints, exploring the conditions leading to different traffic regimes in mixed-traffic systems.

Findings

Platoons dissolve with lower passenger rates or higher bus densities.

Critical passenger arrival rate depends exponentially on vehicle density.

Close stop spacing at low densities induces platooning, reducing speeds.

Abstract

We modify the Nagel-Schreckenberg (NaSch) cellular automata model to study mixed-traffic dynamics. We focus on the interplay between passenger availability and bus-stopping constraints. Buses stop next to occupied cells of a discretized sidewalk model. By parametrizing the spacing distance between designated stops, our simulation covers the range of load-anywhere behavior to that of well-spaced stops. The interplay of passenger arrival rates and bus densities drives crossover transitions from platooning to non-platooned (free-flow and congested) states. We show that platoons can be dissolved by either decreasing the passenger arrival rate or increasing the bus density. The critical passenger arrival rate at which platoons are dissolved is an exponential function of vehicle density. We also find that at low densities, spacing stops close together induces platooned states, which reduces system speeds and increases waiting times of passengers.