Theoretical investigation, simulation and empirical analysis of the growth pattern of traffic oscillations in the Euler coordinates

TL;DR

This paper explores whether the growth pattern of traffic oscillations observed in vehicle platoons can be transferred to the road location framework, combining theoretical, simulation, and empirical analyses to validate the relationship.

Contribution

It unifies Lagrangian and Eulerian measurements of traffic oscillations, revealing their mapping relationship and demonstrating the transferability of growth patterns across frameworks.

Findings

Theoretical mapping between Lagrangian and Eulerian oscillation measurements.

Simulation results confirm the transferability of growth patterns.

Empirical analysis with NGSIM data supports the theoretical findings.

Abstract

The formation and development of oscillations is an important traffic flow phenomenon. Recent studies found that along a vehicle platoon described in the Lagrangian specification, traffic oscillations grow in a concave way. Since stationary bottlenecks are more intuitively described in the Eulerian framework, this paper investigates whether the concave growth pattern of traffic oscillations in the Lagrangian coordinates can be transferred to the Euler coordinates (i.e. the concave increase in standard deviation is no longer measured across the vehicle indices but as a function of the road location). To this end, we theoretically unify these two ways of measuring oscillations by revealing their mapping relationship. We show that the growth pattern measured in the Lagrangian coordinates can be transferred to the Euler coordinates. We believe this finding is nontrivial since the scenarios are significantly different: while in vehicle platoons (Lagrangian view, non-penetrable moving bottleneck), the speed variance for a given vehicle is ideally constant, the drivers in the Eulerian setting (penetrable stationary bottleneck triggering the waves) experience all amplitudes, first the big ones and then the small ones. To test this proposition, we performed simulation using two different kinds of car-following models. Simulation results validate the theoretical analysis. Finally, we performed empirical analysis using the NGSIM data, which also validates the theoretical analysis.