Road design

Cover of Expanded Operating Speed Model
Expanded Operating Speed Model
  • Publication no: AP-T229-13
  • ISBN: 978-1-921991-85-1
  • Published: 3 April 2013

Austroads Project TS1456 (Expanded Operating Speed Model) was established to update and expand the road design operating speed models used in Australia. In particular, the project reviewed the validity of the existing operating speed model for rural roads and identified adjustments to the model that reflect changes in driver speed behaviour. This included the deceleration of cars and heavy vehicles on horizontal curves and the influence of horizontal curves in sequence.

This report documents the process used to collect and analyse speed data on horizontal curves, and assesses the implications in terms of the deceleration on curves for cars and trucks and the influence of curves in sequence. The report includes potential revisions for the existing operating speed model for horizontal curves.

  • 1. Introduction
    • 1.1. Background
      • 1.1.1. Deceleration on Horizontal Curves Model for Rural Roads
      • 1.1.2. Operating Speed Model for Articulated Trucks on Rural Roads
      • 1.1.3. Curves in Sequence
    • 1.2. Purpose of Report
    • 1.3. Structure of Report
  • 2. Method
    • 2.1. Identifying Horizontal Curve Sites
    • 2.2. Identifying Curves
      • 2.2.1. Desire Curve Features
      • 2.2.2. Data Collection Sites
      • 2.2.3. Banded Speed Measurements
    • 2.3. Validating the Existing Operating Speed Model
      • 2.3.1. Determining Speed Reduction through Curve
      • 2.3.2. Comparing Predicted and Measured Speed Reduction on Curves
      • 2.3.3. Developing Revised Deceleration on Horizontal Curves Models
    • 2.4. Curves in Sequence
  • 3. Results
    • 3.1. Introduction
    • 3.2. Deceleration on Horizontal Curves Models for Cars
      • 3.2.1. Small Radius Curves
      • 3.2.2. Medium Radius Curves
      • 3.2.3. Not Included in the Analysis
    • 3.3. Articulated Trucks
      • 3.3.1. Differences between Articulated Truck and Car Speeds
      • 3.3.2. Deceleration on Horizontal Curves Model for Articulated Trucks
    • 3.4. Curves in Sequence
      • 3.4.1. Curve Sites
      • 3.4.2. Larger Radius Curve Followed by Smaller Radius Curve
      • 3.4.3. Smaller Radius Curve Followed by Larger Radius Curve
    • 3.5. Discussion of Results
      • 3.5.1. Deceleration of Cars on Horizontal Curves
      • 3.5.2. Articulated Trucks
      • 3.5.3. Curves in Sequence
      • 3.5.4. Data Collection and Analysis Factors
  • 4. Conclusions and FURTHER CONSIDERATIONS
    • 4.1. Conclusions
    • 4.2. Further Considerations
  • References
  • Appendix A Speed parameter terminology
  • A.1 Operating Speed
  • A.2 Operating Speed of Trucks
  • A.3 Desired Speed
  • A.4 Section Operating Speed
  • A.5 Limiting Curve Speed
  • A.6 Speed Environment
  • Appendix B Deceleration on Curves Model
  • B.1 VicRoads Deceleration on Curves Model
  • Appendix C Curve Identification, Data Collection and Collation
  • C.1 Curve Site Identification
  • C.1.1 Obtaining Data
  • C.1.2 Analysing Curve Criteria Data
  • C.2 Pneumatic Tube Counts
  • C.2.1 Using Tube Counts for Speed Measurements
  • C.2.2 Locating Pneumatic Tube Counts
  • C.3 Data Collection
  • C.4 Vehicle Classification
  • C.5 Banded Speeds
  • C.5.1 Developing Banded Speed Profiles
  • C.5.2 Application of Banded Speed Data
  • C.6 Determining Speed Reduction on Curve
  • C.6.1 Aligning Banded and Operating Speed Measurements
  • C.6.2 Other Considerations
  • C.6.3 Applying Speed Measurements
  • C.6.4 Factors Related to Use of Banded Speed Data
  • Appendix D Curve Sites
  • Appendix E Speed data
  • E.1 Cars
  • E.2 Articulated Trucks
  • Appendix F Revised deceleration on Curves Model
  • Appendix G Analysis Results
  • G.1 Introduction
  • G.2 Car Deceleration on Horizontal Curves
  • G.2.1 Results
  • G.2.2 Comparison of Existing and Revised Models
  • G.3 Articulated Truck Deceleration on Horizontal Curves
  • G.3.1 Difference between Articulated Truck and Car Speed on Horizontal Curves
  • G.3.2 Articulated Truck Deceleration on Horizontal Curves
  • G.4 Curves in Sequence
  • G.4.1 Barkers Lodge Road Curves in Sequence
  • G.4.2 Healesville-Kinglake Road Curves in Sequence
  • Appendix H Superelevation
  • H.1 Isolated Curves
  • H.2 Curves in Sequence
  • H.2.1 Upstream Curves
  • H.2.2 Connecting Straights
  • H.2.3 Downstream Curves