Multiple Sources of Safety Information From V2V and V2I: Redundancy, Decision Making, and Trust - Safety Message Design Report

FOREWORD

Vehicles and roadways of the future will employ advanced communications technologies to facilititate applications to make driving safer, more efficient, and more environmentally friendly. The safety benefits will largely be achieved by communicating relevant safety information to the driver. The Human Factors for Connected Vehicles research program is focused on understanding, assessing, planning for, and counteracting the effects of signals or system-generated messages that take a driver’s eyes off the road (visual distraction), the driver’s mind off the driving task (cognitive distraction), and the driver’s hands off the steering wheel (manual distraction). The overall goal of this research is to support the introduction of this technology as a benefit to all transportation users.

The research described in this report provides some intial design guidance for vehicle-to-infrastructure (V2I) safety messages as well as some limited guidance for vehicle-to-vehicle systems. This report primarily uses existing transportation safety research, as well as research from related domains. This information can be used by connected-vehicle system designers and other State transportation department personnel to develop and implement V2I applications, to make sure these systems work effectively and safely within a larger vehicle-to-infrastructure, vehicle-to-vehicle, and vehicle-to-device environment. In this way, these findings will help make the interaction of roadway and vehicle systems safer, reduce the likelihood of crashes and injuries, and increase safety for all roadway users.

Monique R. Evans, P.E.
Director, Office of Safety
Research and Development

Technical Report Documentation Page

SI* (Modern Metric) Conversion Factors

* SI is the symbol for the International System of Units. Appropriate rounding should be made to comply with Section 4 of ASTM E380. (Revised March 2003)

Table of Contents

• Chapter 1. Introduction
  • Background
  • Overview of the Report
    
    
• Chapter 2. Overview of CV Applications
  • CV Communication Architecture
    • V2V
    • V2I
    • Vehicle-to-Infrastructure, Vehicle-to-Vehicle, and Vehicle-to-Device (V2X)
    • DII
    • DVI
    • RSE
  • Summaries of Safety Applications Discussed in this Report
    • SSA
    • SLTA
    • RLVW
    • CSW
    • SWIW-RS
      
      
• Chapter 3. DII Safety Message Guideline Information
  • Topic 1. Considerations for Adding a DII to a CV RSE
    • Introduction
    • Guideline
    • Discussion
    • Design Issues
  • Topic 2. System-level Conflicts
    • Introduction
    • Guideline
    • Discussion
    • Design Issues
  • Topic 3. Message-level Incongruence Between DII and DVI Systems
    • Introduction
    • Guidelines
    • Discussion
  • Topic 4. Message Content: Message Elements
    • Introduction
    • Guideline
    • Discussion
    • Design Issues
  • Topic 5. Message Content: Use of Symbols and Text
    • Introduction
    • Guideline
    • Discussion
    • Design Issues
  • Topic 6. Supporting Driver Trust of Safety Systems
    • Introduction
    • Guideline
    • Discussion
  • Topic 7. Factors that Affect Gap Choice
    • Introduction
    • Guidelines
    • Discussion
    • Design Issues
  • Topic 8. Intersection Decision Support for Stop-controlled Minor and Major Road Junctions
    • Introduction
    • Guidelines
    • Discussion
    • Design Issues
  • Topic 9. SLTA
    • Introduction
    • Guideline
    • Discussion
  • Topic 10. RLVW
    • Introduction
    • Guideline
    • Discussion
    • Design Issues
  • Topic 11. CSW
    • Introduction
    • Guideline
    • Discussion
    • Design Issues
  • Topic 12. Road Weather: General Human Factors Considerations
    • Introduction
    • Design Guidance
    • Discussion
    • Design Issues
      
      
• Chapter 4. Summary and Conclusions
• References

List of Figures

• Figure 1. Photo. CICAS-SSA (DII) prototype implemented by Minnesota
• Figure 2. Photo. CICAS-SLTA implemented at a signalized intersection
• Figure 3. Photo. Example of a CICAS-V DII
• Figure 4. Photo. DCWS
• Figure 5. Illustration. Two-phase CMS display showing weather advisory
• Figure 6. Illustration. Example sign locations that consider ISD
• Figure 7. Diagram. Comparison of graphical displays for intersection decision support systems that send messages to drivers on the major road, minor road, or both
• Figure 8. Photo. General region drivers scan when making an LTAP of oncoming traffic
• Figure 9. Illustration. MUTCD symbol for “No Left Turn” that was presented on the DII to examine drivers’ understanding of the SLTA system
• Figure 10. Illustration. MUTCD symbol for “Left Turn Yield” that was presented on the DII to examine drivers’ understanding of the SLTA system

List of Tables

• Table 1. DII safety message guideline information
• Table 2. Operational and situational factors related to DII installation
• Table 3. System activation overlap matrix
• Table 4. Definitions of message characteristics related to congruence
• Table 5. Message elements for consideration
• Table 6. Enumerated combinations of message elements by warning system
• Table 7. General considerations for implementing symbols and text elements in signs
• Table 8. Design considerations that affect driver trust
• Table 9. Situational/site factors that can affect gap choice
• Table 10. Driver/vehicle characteristics that can affect gap acceptance decisions
• Table 11. General design considerations for intersection characteristics
• Table 12. Timing factors that affect RLVW compliance
• Table 13. Example DIIs for the RLVW as a function of condition/utilization
• Table 14. DII Elements to support horizontal curves
• Table 15. Criteria for legibility distances by seconds of visibility
• Table 16. Differences in presenting weather information via DII and DVI
• Table 17. Presenting weather information via DII and DVI

List of Abbreviations