Investigating the Effects of External Communication and Platoon Behavior on Manual Drivers at Highway Access

Title of the Paper

Investigating the Effects of External Communication and Platoon Behavior on Manual Drivers at Highway Access

Paper Information

• Subject Area: Interaction between automated vehicles and manually driven vehicles, focusing on the impact of platoon behavior and external communication design at highway entrances.
• Keywords: Automated vehicles, external communication, virtual reality, platoon behavior, human-computer interaction, highway access, trust, cognitive load, sense of safety

Research Background and Problem

• Identified Issues or Challenges: The introduction of automated vehicles (AVs) is expected to enhance traffic safety and efficiency, with platoon behavior achieving benefits through reduced air resistance. However, such platoon behavior may create uncertainty and challenges for manually driven vehicles attempting to merge onto highways in mixed traffic scenarios.

  While existing research has extensively explored interactions between AVs and pedestrians, there is a lack of studies addressing the interaction between AVs and manually driven vehicles in mixed traffic contexts.

• Why This Problem Is Important: As automated driving technology advances, the coexistence of AVs and traditional manually driven vehicles during the transitional phase is an inevitable reality. Designing interaction schemes that ensure both safety and efficiency is critical for achieving a seamless transition in complex driving scenarios. Additionally, such research contributes to policy development and technological implementation.

• Research Motivation and Related Work: This study builds upon existing research on how AVs interact with pedestrians, manually driven vehicles, and bottleneck road segments. However, there is a lack of practical evaluation regarding the impact of platoon behavior at highway entrances. This study expands the research domain through virtual reality simulation experiments.

Proposed Solution

• Proposed Solution: The authors designed a study in a virtual reality environment to evaluate the impact of different platoon behaviors and communication designs on the driving behavior of manual drivers. Two platoon behaviors (single large gap and multiple small gaps) and three communication designs (augmented reality (AR), vehicle-mounted eHMI displays, and head-up display (HUD)) were proposed.

• Innovative Aspects of the Solution:

  • Proposed two platoon behavior designs suitable for manual drivers merging onto highways with automated vehicles.
  • Systematically compared the effects of three different communication strategies on drivers' cognitive load, trust, and sense of safety.
  • Utilized virtual reality technology to realistically simulate complex driving scenarios, enabling reliable collection of both subjective and objective data.

• Implementation Steps and Key Technologies:

  1. Experimental Design: Simulated highway entrance scenarios with four platoon behaviors and four communication levels, resulting in 17 conditions.
  2. Virtual Reality Technology: Built virtual driving scenarios using the Unity engine, equipped with HTC VIVE Pro Eye and a steering wheel for simulated driving operations.
  3. Measurement Dimensions: Objective data included speed, total time, platoon gap, and accident occurrences; subjective data included drivers' trust, sense of safety, and cognitive load.
  4. Data Analysis: Employed non-parametric statistical analysis (Aligned Rank Transform, ART) and Dirichlet regression to analyze eye-tracking data distribution.

Research Findings

• Specific Findings:

  • The single large gap (70m) and augmented reality (AR) communication method were identified as the most preferred designs, significantly improving participants' trust, predictability, and sense of safety.
  • AR communication design excelled in reducing cognitive load and attention demands and was frequently observed across all platoon behaviors.
  • Multiple small gaps (30m or 45m) resulted in higher accident rates, while the single large gap design had almost no accidents.

• Advantages Over Existing Solutions:

  • This study clearly revealed manual drivers' behavioral preferences and psychological responses in complex scenarios, providing significant insights for designing automated systems with platoon behavior.
  • Experimental results confirmed the advantages of AR communication in reducing cognitive load and enhancing behavioral clarity.
  • Balanced the technical complexity and practical feasibility of communication design.

• Experimental or Evaluation Results:

  • Experiments under various combinations of platoon behaviors and communication designs showed that AR and large gap designs not only reduced accident rates but also significantly enhanced participants' trust in the system.
  • Data indicated that most participants chose to merge into platoon gaps, validating the positive influence of the design on driving behavior.
  • While the single large gap design reduced traffic efficiency, its safety benefits were significant, suggesting future efforts to optimize the balance between safety and efficiency.

• Limitations and Future Directions:

  • The participant group was predominantly young and male, necessitating further validation for broader applicability across different age and gender groups.
  • The use of virtual reality simulations may not fully capture real-world cautious behavior, suggesting future studies incorporate high-fidelity simulators or field experiments.
  • The assumed communication technologies are relatively advanced; subsequent research should validate findings using mature technologies (e.g., 3D displays or other sensory modalities).
  • Further exploration of gap design parameter optimization is needed to enhance both traffic efficiency and safety in platoon systems.

This study provides critical insights for the safe and efficient integration of automated vehicles into mixed traffic scenarios, establishing a foundational framework for policymakers and system designers.