Inefficient emergent oscillations in intersecting driven many-particle flows

TL;DR

This paper investigates how intersecting pedestrian and vehicle flows can produce inefficient oscillations that paradoxically reduce delays, challenging the assumption that oscillations always improve flow efficiency.

Contribution

It demonstrates that in coupled pedestrian-vehicle systems, increasing safety gaps can decrease delays, revealing a slower-is-faster effect in emergent oscillations.

Findings

Oscillations can reduce average delays for pedestrians and vehicles.

Increasing pedestrian safety gaps can improve overall flow.

The slower-is-faster effect is explained through the underlying mechanism.

Abstract

Oscillatory flow patterns have been observed in many different driven many-particle systems. The conventional assumption is that the reason for emergent oscillations in opposing flows is an increased efficiency (throughput). In this contribution, however, we will study intersecting pedestrian and vehicle flows as an example for inefficient emergent oscillations. In the coupled vehicle-pedestrian delay problem, oscillating pedestrian and vehicle flows form when pedestrians cross the street with a small time gap to approaching cars, while both pedestrians and vehicles benefit, when they keep some overcritical time gap. That is, when the safety time gap of pedestrians is increased, the average delay time of pedestrians decreases and the vehicle flow goes up. This may be interpreted as a slower-is-faster effect. The underlying mechanism of this effect is explained in detail.