Road design

Cover of Review of Motorway Entrance Ramp Acceleration Lengths
Review of Motorway Entrance Ramp Acceleration Lengths
  • Publication no: AP-R500-15
  • ISBN: 978-1-925294-87-3
  • Published: 7 December 2015

This report investigates whether the ramp acceleration lengths provided in the Austroads Guides are valid for modern Australian vehicles.

The study included a literature review, speed data collection and crash analysis.

It found that the current method of using passenger vehicles as the design vehicle for acceleration on entrance ramps is appropriate. There is also potential for reducing acceleration lengths at entrance ramps to generate capital and operational cost savings, and higher implied acceleration rates may be appropriate for entrance ramps.

Further research is required to investigate human factors and design elements that affect acceleration rates and to ascertain whether acceleration rates could be increased, thereby reducing acceleration lengths.

  • Summary
  • 1. Introduction
    • 1.1. Background
    • 1.2. Objectives
    • 1.3. Purpose
  • 2. Methodology
    • 2.1. Literature Review
    • 2.2. Data Collection and Processing
      • 2.2.1. Study Sites
      • 2.2.2. Equipment
      • 2.2.3. Data Collection Process
      • 2.2.4. Data Processing
    • 2.3. Crash Analysis
  • 3. Literature Review Findings
    • 3.1. Components of Entrance Ramps
    • 3.2. Sources of Entrance Ramp Acceleration Lengths
    • 3.3. Determination of Entrance Ramp Acceleration Lengths
    • 3.4. Grade Correction Factors
    • 3.5. Grade Correction Factors Determination
    • 3.6. Ramp Metering
      • 3.6.1. Purpose of Ramp Metering
      • 3.6.2. Types of Ramp Metering
  • 4. Field Investigation
    • 4.1. Collected Data
    • 4.2. Data Analysis
      • 4.2.1. Overview
      • 4.2.2. Speed and Acceleration over Distance
      • 4.2.3. Entry Speeds, Merge Speeds and Merge Lengths
      • 4.2.4. Grade Data
    • 4.3. Discussion
      • 4.3.1. Performance of Current Passenger Cars
      • 4.3.2. Implied Average Acceleration Suggested by Design Guides
      • 4.3.3. Acceleration and Grade Relationships
      • 4.3.4. Ramp Length and Merge Speed
      • 4.3.5. Ramp Signals
  • 5. Crash Analysis
    • 5.1. Overview of Results
    • 5.2. Number of Crashes and Severity
    • 5.3. Crash Types by DCA Code
    • 5.4. Vertical Alignment
    • 5.5. Weather Condition
    • 5.6. Lighting Condition
    • 5.7. Horizontal Alignment
    • 5.8. Crash Rates
    • 5.9. Other Factors
    • 5.10. Relationship between Crash Rate and Ramp Features
      • 5.10.1. Crash Rate versus Merge Length
      • 5.10.2. Crash Rate versus Maximum Upgrade
  • 6. Discussion
    • 6.1. General Characteristics
    • 6.2. Potential for Shorter Acceleration Lengths
    • 6.3. Heavy Vehicles
    • 6.4. Ramp Signals
    • 6.5. Speed Data Collection and Crash Analysis
  • 7. Conclusions and Recommended Further Investigations
    • 7.1. Conclusions
    • 7.2. Recommended Further Investigations
  • References
  • Appendix A Data Collection Sites
  • A.1 Pacific Motorway, Sports Drive, Springwood Northbound
  • A.2 Pacific Motorway, Grandis Street, Tanah Merah Northbound
  • A.3 Pacific Motorway, Stapylton-Jacobs Well Road, Yatala Northbound
  • A.4 Pacific Motorway, Nielsens Road, Carrara Southbound
  • A.5 Pacific Motorway, Elysium Drive, Worongary Southbound
  • A.6 South East Freeway, Duke Street Northbound
  • A.7 South East Freeway, Marquis Street Southbound
  • A.8 South East Freeway, Logan Road Northbound
  • A.9 Western Freeway, Moggill Road Southbound
  • A.10 Western Freeway, Moggill Road Northbound
  • A.11 Bruce Highway (Anzac Avenue Northbound)
  • A.12 Bruce Highway, Anzac Avenue Southbound
  • A.13 Bruce Highway, Boundary Road Northbound
  • A.14 Bruce Highway, Boundary Road Southbound
  • A.15 Bruce Highway, Pumicestone Road Northbound
  • A.16 Bruce Highway, Maroochydore Road Northbound
  • A.17 Sunshine Motorway, Maroochy Boulevard Southbound
  • A.18 Bruce Highway, Maroochydore Road Southbound
  • A.19 Caloundra Road, Racecourse Road Westbound
  • A.20 Caloundra Road, Racecourse Road Eastbound
  • Appendix B Speed – Distance Distributions
  • B.1 Pacific Motorway, Sports Drive, Springwood Northbound
  • B.2 Pacific Motorway, Grandis Street, Tanah Merah Northbound
  • B.3 Pacific Motorway, Stapylton – Jacobs Well Road, Yatala Northbound
  • B.4 Pacific Motorway, Nielsens Road, Carrara Southbound
  • B.5 Pacific Motorway, Elysium Drive, Worongary Southbound
  • B.6 South East Freeway, Duke Street Northbound
  • B.7 South East Freeway, Marquis Street Southbound
  • B.8 South East Freeway, Logan Road Northbound
  • B.9 Western Freeway, Moggill Road Southbound
  • B.10 Western Freeway, Moggill Road Northbound
  • B.11 Bruce Highway, Anzac Avenue Northbound
  • B.12 Bruce Highway, Anzac Avenue Southbound
  • B.13 Bruce Highway, Boundary Road Northbound
  • B.14 Bruce Highway, Boundary Road Southbound
  • B.15 Bruce Highway, Maroochydore Road Northbound
  • B.16 Sunshine Motorway, Maroochy Boulevard Southbound
  • B.17 Bruce Highway, Maroochydore Road Southbound
  • B.18 Caloundra Road, Racecourse Road Eastbound
  • B.19 Caloundra Road, Racecourse Road Westbound
  • Appendix C Grade – Acceleration Distributions
  • C.1 Pacific Motorway, Sports Drive, Springwood Northbound
  • C.2 Pacific Motorway, Grandis Street, Tanah Merah Northbound
  • C.3 Pacific Motorway, Stapylton-Jacobs Well Road, Yatala Northbound
  • C.4 Pacific Motorway, Nielsens Road, Carrara Southbound
  • C.5 Pacific Motorway, Elysium Drive, Worongary Southbound
  • C.6 South East Freeway, Duke Street Northbound
  • C.7 South East Freeway, Marquis Street Southbound
  • C.8 South East Freeway, Logan Road Northbound
  • C.9 Western Freeway, Moggill Road Southbound
  • C.10 Western Freeway, Moggill Road Northbound
  • C.11 Bruce Highway, Anzac Avenue Northbound
  • C.12 Bruce Highway, Anzac Avenue Southbound
  • C.13 Bruce Highway, Boundary Road Northbound
  • C.14 Bruce Highway, Boundary Road Southbound
  • C.15 Bruce Highway, Maroochydore Road Northbound
  • C.16 Sunshine Motorway, Maroochy Boulevard Southbound
  • C.17 Bruce Highway, Maroochydore Road Southbound
  • C.18 Caloundra Road, Racecourse Road Eastbound
  • C.19 Caloundra Road, Racecourse Road Westbound