[Paper Review] Dedicated Lane for Connected and Automated Vehicle: How Much Does A Homogeneous Traffic Flow Contribute?

Zijia Zhong, Joyoung Lee|arXiv (Cornell University)|Jun 30, 2019

Traffic control and management23 references4 citations

TL;DR

This paper investigates how dedicated connected and automated vehicle (CAV) lanes improve traffic flow characteristics at varying market penetration rates (MPR). Using headway distribution, communication density, and speed-flow diagrams, it demonstrates that a single CAV lane increases optimal flow to 3,400 vehicles per lane per hour at 90% MPR, narrows headway variability, and stabilizes communication density, reducing packet drop risk.

ABSTRACT

Dedicated lanes for connected and automated vehicles (CAVs) can not only provide the technological accommodation, but also the desired market incentive for road user to adapt CAVs. Thus far, the majority of the impact assessment of CAV focused on the network-wide benefits. In this paper, we investigate the change of the traffic flow characteristic with two configurations of dedicated CAV lane across levels of market penetration. The traffic flow characteristics are quantified from the perspectives of headway distribution, communication density, and speed-flow diagram. The results highlight the contributions of the CAV lane. First, CAV lanes significantly improves the speed-flow characteristics by extending the stable region of the speed-flow curve and yielding a greater optimum flow. The highest value of optimum flow is 3400 vehicle per lane per hour at 90% MPR with one CAV lane. Furthermore, the concentration of CAVs at a lane results a narrower headway distribution (with smaller standard deviation), even with partial market penetration. Moreover, the CAV lane creates a more consistent CAV density which maintains the communication density level at a predictable level, hence decreasing the probability of packet drop.

Motivation & Objective

• To evaluate the impact of dedicated CAV lanes on traffic flow characteristics across different market penetration rates (MPR).
• To quantify improvements in speed-flow relationships, headway distribution, and communication density due to CAV lane implementation.
• To assess how CAV lane configuration supports stable, predictable communication and reduces packet drop probability.

Proposed method

• Modeling two traffic configurations: mixed traffic and dedicated CAV lane with varying CAV market penetration.
• Analyzing headway distribution to assess temporal spacing consistency among vehicles.
• Measuring communication density based on vehicle proximity and CAV concentration per lane.
• Constructing speed-flow diagrams to identify stable flow regions and optimal flow rates.
• Using statistical analysis to compare standard deviation of headway and consistency of CAV density across configurations.
• Simulating traffic flow under controlled conditions to isolate the effects of dedicated CAV lanes.

Experimental results

Research questions

• RQ1 How does a dedicated CAV lane affect the speed-flow relationship at different market penetration rates?
• RQ2 To what extent does a CAV lane reduce headway variability compared to mixed traffic flow?
• RQ3 How does CAV lane configuration influence communication density consistency and packet drop probability?
• RQ4 What is the maximum achievable optimal flow rate with a single CAV lane at high market penetration?
• RQ5 How does CAV concentration in a dedicated lane affect the predictability of communication performance?

Key findings

• The dedicated CAV lane extends the stable region of the speed-flow curve and increases the optimal flow rate to 3,400 vehicles per lane per hour at 90% market penetration.
• Even at partial market penetration, the CAV lane reduces headway distribution standard deviation, indicating more consistent spacing between vehicles.
• The concentration of CAVs in a single lane leads to a more predictable and consistent CAV density, improving communication reliability.
• The stabilized CAV density maintains communication density at a consistent level, thereby decreasing the probability of packet drop.
• The CAV lane enhances traffic flow stability and efficiency by enabling smoother, more predictable vehicle interactions.