Integrated Variable Speed Limits and Lane-Changing Control for Freeway Lane-Drop Bottlenecks

Yuqing Guo,Danya Yao,Yi Zhang,Huile Xu

doi:10.1109/access.2020.2981658

Abstract

There are generally two kinds of traffic control strategies to relieve traffic congestion in lane-drop bottlenecks: variable speed limits (VSL) control and lane-changing (LC) control. However, VSL has limited or even no effect due to many mandatory LC maneuvers near bottlenecks, while LC fails to reduce traffic congestion when traffic demand is high. Although a few control methods combine VSL and LC, they do not consider the interaction between VSL and LC, which rules out many potentially good alternatives. We instead propose an integrated VSL and LC control method under a connected and automated vehicle (CAV) environment, which can consider the interaction and simultaneously find the values of LC numbers and speed limits to maximize traffic efficiency. Our control is in the framework of the model predictive control (MPC), which consists of prediction, optimization, and implementation. We adopt an improved multi-class cell transmission model (CTM) for traffic state prediction, then use the genetic algorithm (GA) for optimization which optimizes traffic network performance, and implement our control method in the SUMO platform. Simulation results demonstrate that our control method greatly improves the capacity of the road and is robust to different traffic demands and scenarios. Our control outperforms no control and VSL-only control in travel time and exhaust emissions, which reduces total travel time by 23.86% to 44.62% and exhaust emissions by 10.29% to 48.19%.

Highlights

Lane-drop, such as incident lane blockage, road construction, or inherent design flaws, is common in freeways due to various reasons
Our method considers the interaction between variable speed limits (VSL) and LC in the formulas of multi-class cell transmission model (CTM) and finds the proper combination of VSL and LC by solving an optimization problem of online model predictive control (MPC)
We propose a new refined integrated VSL and LC control method aiming at freeway bottlenecks under mixed traffic flows in this paper

Summary

INTRODUCTION

Lane-drop (reduction in the number of lanes), such as incident lane blockage, road construction, or inherent design flaws, is common in freeways due to various reasons. Y. Guo et al.: Integrated VSL and LC Control for Freeway Lane-Drop Bottlenecks of existing work adopts variable speed limits (VSL) control methods to overcome the ‘‘capacity drop’’ phenomenon [4] and improve traffic efficiency near lane-drop bottlenecks [5], [6]. Different from existing methods, which first use LC to improve road capacity and use VSL to reduce congestion, we simultaneously find the values of LC numbers and speed limits to maximize traffic efficiency. In this way, our method can benefit from the two control strategies fully.

BACKGROUND

THE GA BASED TRAFFIC CONTAOL

CONCLUSION