Where Should Traffic Sensors Be Placed on Highways?

TL;DR

This paper presents a control-theoretic and optimization-based approach to determine optimal traffic sensor placement on highways with ramps, aiming to maximize network-wide traffic observability and density estimation accuracy.

Contribution

It introduces a novel method combining observability analysis and integer programming for sensor placement using nonlinear traffic models, specifically the asymmetric cell transmission model.

Findings

Effective sensor placement strategies improve traffic density estimation.

The approach is validated through numerical case studies.

Method can be extended to other traffic dynamic models.

Abstract

This paper investigates the practical engineering problem of traffic sensors placement on stretched highways with ramps. Since it is virtually impossible to install bulky traffic sensors on each highway segment, it is crucial to find placements that result in optimized network-wide, traffic observability. Consequently, this results in accurate traffic density estimates on segments where sensors are not installed. The substantial contribution of this paper is the utilization of control-theoretic observability analysis -- jointly with integer programming -- to determine traffic sensor locations based on the nonlinear dynamics and parameters of traffic networks. In particular, the celebrated asymmetric cell transmission model is used to guide the placement strategy jointly with observability analysis of nonlinear dynamic systems through Gramians. Thorough numerical case studies are presented to corroborate the proposed theoretical methods and various computational research questions are posed and addressed. The presented approach can also be extended to other models of traffic dynamics.