A Lagrangian approach for variable speed limit implementation in C-ITS framework

Abstract

With the development of Cooperative-Intelligent Transport System (C-ITS) technologies, new strategies based on embedded technologies have emerged to manage road networks. This paper focuses on adapting to this connectivity context a Variable Speed Limit (VSL) system to detect shockwaves and anticipate their propagation based on the kinematic wave theory to dampen them. We provide an alternative framework to adapt the VSL strategy, well-suited for Eulerian approaches, into a Lagrangian context. While the Eulerian approach is based on Loop Detector (LD) and macroscopic traffic indicators (e.g. flow, density), our Lagrangian approach relies on Road Side Units (RSUs) that record the GPS traces shared by Connected Vehicles (CVs). Based on the combination of CV trajectories, Fundamental and Space-Time Diagrams theory, shockwave estimation and prediction processes directly operate on congestion waves, which release the estimation issue for traffic density. The simulation-based analysis reveals that the performance of the Lagrangian approach is comparable to the Eulerian configurations.

Keywords:

• Variable speed limit
• C-ITS
• Lagrangian
• Eulerian
• shockwave

Acknowledgments

The contents of this publication are the sole responsibility of the INDID Consortium and do not necessarily reflect the opinion of the European Union. The authors confirm their contribution to the paper as follows: study conception and design: P.-A. Laharotte, K. Bhattacharyya, E. Fauchet, N.-E. El Faouzi; data collection: E. Fauchet, K. Bhattacharyya; analysis and interpretation of results: E. Fauchet, P.-A. Laharotte, K. Bhattacharyya; draft manuscript preparation: E. Fauchet, P.-A. Laharotte, K. Bhattacharyya, N.-E. El Faouzi. All authors reviewed the results and approved the final version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 Please note that $V_{\mathrm{shockwave}}\le V_{\mathrm{Threshold}}$. In contrary to original versions (Hegyi et al. 2008), we feature state 2 with an estimated average speed $V_{\mathrm{shockwave}}$, which better represent the traffic state than using directly $V_{\mathrm{Threshold}}$.

Additional information

Funding

This work was supported by the INDID and C-ROADS C-ROADS -- The Platform of Harmonised C-ITS Deployment in Europe (2019) project under Grant INEA/CEF/TRAN/M2018/1788494, co-financed by the Connecting Europe Facility of the European Union.