Road Design
Background to the Development of the 2020 Edition of Guide to Road Design Part 6
- Publication no: AP-R628-20
- ISBN: 978-1-922382-09-2
- Published: 10 August 2020
- PDF (free) Download
This research report documents a proposed process to evaluate roadsides risk for inclusion into Austroads’ Guide to Road Design Part 6: Roadside Design, Safety and Barriers. The report provides background information about the proposed guidance.
The guidance for evaluating roadside safety treatments is based on an evaluation process described in the US procedure Roadside Safety Analysis Program version 3 (RSAPv3) and published in Ray et al (2012a).
There are two appendices:
- Appendix A describes the process.
- Appendix B provides equations for calculating the risk score to beused in the proposed procedure in the revision to the AustroadsGuide to Road Design Part 6: Roadside Design, Safety andBarriers.
- Summary
- 1. Background
- 1.1 Operating Speed
- 2. Exposure
- 2.1 Base Exposure Measure for Undivided Roads
- 2.2 Base Exposure Measure for Divided Roads
- 2.3 Exposure Modification Factors
- 3. Likelihood
- 3.1 Evaluation of Australian Data
- 3.2 Likelihood for Lateral Movement on Straight Roads
- 3.3 Adjustment for Curves
- 3.4 Measuring Lateral Distances
- 3.5 Likelihood of a Vehicle Colliding with an Oncoming Vehicle
- 3.6 Likelihood of Colliding with Isolated (Point) Hazards
- 4. Impact Crash Severity
- 4.1 Current Processes
- 4.2 RSAPv3 Severity Indices
- 4.3 Converting Severity Indices from AGRD part 6 to RSAPv3 Values
- 4.4 Converting the Severity Indices to a Trauma Measure (Trauma Indices)
- 4.5 Severity of Head on Impacts
- 4.6 Effect of Speed on Severity
- 4.7 Trauma Indices for a Range of Hazards Currently Described in AGRD Part 6
- 4.8 The Performance of Barriers
- 4.9 Classification of Severities into Groups
- 5. Risk Due to Rollover
- 5.1 Roadside Safety Analysis Program (RSAPv3)
- 5.2 Austroads Research
- 5.3 Carrigan and Sheikh
- 5.4 Discussion and Application to AGRD Part 6
- 5.4.1 Trauma Indices for Embankments and Verges 6:1 and Flatter
- 5.4.2 Likelihood of a Rollover
- 6. Risk Assessment
- 6.1 Risk Score
- 6.1.1 Collective Risk
- 6.1.2 Individual Risk
- 6.2 Limitations of the Risk Assessment Process
- 6.1 Risk Score
- 7. Application of Procedure
- 7.1 Application to Roadsides with Consistent and Continuous Roadside Attributes
- 7.2 Application to Roadsides with Point Hazards
- 8. Concluding Remarks
- References
- Appendix A Detailed Risk Evaluation Procedure
- A.1 Evaluating the Exposure for a Consistent Roadside
- A.1.1 Calculate the Base Exposure for One Side of the Carriageway
- A.1.2 Exposure Modification Factors
- A.1.3 Determine the Future Traffic Flow
- A.2 Likelihood
- A.2.1 Measuring Lateral Distances
- A.2.2 Likelihood for Background and Consistent Hazards
- A.2.3 Likelihood for Oncoming Vehicles on Two Lane Rural Roads
- A.2.4 Likelihood of Colliding with Isolated (Point) Hazards
- A.2.5 Likelihood of a Rollover
- A.3 Severity
- A.3.1 Continuous (Background) Hazards
- A.3.2 Isolated (Point) Hazards
- A.3.3 Roadside Barriers
- A.3.4 Oncoming Vehicles
- A.3.5 Rollover Events
- A.3.6 Trauma Indices for Roadside Features on Roads with Other Operating Speeds
- A.4 Risk Score
- Appendix B Calculation Procedures
- B.1 Equations to Curves in Graphs
- B.2 Spreadsheet
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