Road design

Cover of Speed Reduction Treatments for High-speed Environments
Speed Reduction Treatments for High-speed Environments
  • Publication no: AP-R508-16
  • ISBN: 978-1-925294-99-6
  • Published: 17 February 2016

This report examines the performance of different types of speed-reducing treatments (or combinations of treatments) in high-speed environments. The project also considered how desired speed can be aligned with a safe, anticipated operating speed with the goal of making high-speed roads more self-explanatory.

Treatments reviewed included: treatments to support development of road hierarchies in line with the concept of self-explaining roads; perceptual countermeasures; transverse rumble strips; vehicle activated signs; gateway treatments; route-based curve treatments; wide median centrelines; and sight distance adjustments on intersection approaches.

Based on the outcomes of this review, these treatments may merit further consideration for future Austroads research and guidance.

  • Summary
  • 1. Introduction
    • 1.1. Background
    • 1.2. Methods and Outcomes
    • 1.3. Report Structure
  • 2. Speed Management Considerations
    • 2.1. High-speed Road Environments
    • 2.2. Safe System Approach
    • 2.3. Speed Reduction and Speed Maintenance Treatments
    • 2.4. Self-explaining Roads
  • 3. Speed Management Treatments in Higher-speed Environments
    • 3.1. Review of Speed Reduction Treatments
    • 3.2. Treatments to Support Development of Road Hierarchies and Self-explaining Roads
    • 3.3. Perceptual Countermeasures
      • 3.3.1. Previous Research
      • 3.3.2. Austroads Guidance
    • 3.4. Transverse Rumble Strips
      • 3.4.1. Previous Research
      • 3.4.2. Austroads Guidance
    • 3.5. Vehicle Activated Signs
      • 3.5.1. Previous Research
      • 3.5.2. Austroads Guidance
    • 3.6. Gateway Treatments
      • 3.6.1. Previous Research
      • 3.6.2. Austroads Guidance
    • 3.7. Route-based Curve Treatments
      • 3.7.1. Previous Research
      • 3.7.2. Austroads Guidance
    • 3.8. Wide Median Centrelines
      • 3.8.1. Lane Width
      • 3.8.2. Previous Research of Lane Narrowing Treatments
      • 3.8.3. Austroads Guidance
    • 3.9. Sight Distance Adjustments on Approaches to Intersections
      • 3.9.1. Previous Research
      • 3.9.2. Austroads Guidance
  • 4. Road Features and Higher-speed Environments
    • 4.1. Introduction
    • 4.2. Individual Road Features
      • 4.2.1. Horizontal Alignment
      • 4.2.2. Vertical Alignment
      • 4.2.3. Access Points
      • 4.2.4. Road Surface
      • 4.2.5. Road, Lane and Shoulder Width
      • 4.2.6. Number of Lanes
      • 4.2.7. Separation of Driving Directions
      • 4.2.8. Roadside Environment and Vertical Elements
      • 4.2.9. Lateral Clearance
      • 4.2.10. Road Tunnels
    • 4.3. Combined Effect of Road Features
      • 4.3.1. Road Features and Self-explaining Roads
      • 4.3.2. ERASER Project
      • 4.3.3. Credible Speed Limit Tool
      • 4.3.4. Roadway Features and Driver Discomfort
      • 4.3.5. Effect of Shoulder Width, Guardrail and Roadway Geometry
  • 5. Discussion and Conclusions
    • 5.1. Speed Reduction Treatments
    • 5.2. Road Features Influencing Speed
      • 5.2.1. Implications for Austroads Guidance
  • References
  • Appendix A Examples of Gateway Treatments
  • Appendix B Credible Speed Limit Factors