Road design

Cover of Improving Roadside Safety - Stage 2: Interim Report
Improving Roadside Safety - Stage 2: Interim Report
  • Publication no: AP-R387-11
  • ISBN: 978-1-921709-90-6
  • Published: 31 August 2011

This report provides advice to practitioners on management of roadside hazards, and the decision between provision of safety barriers and the relocation or removal of hazards that are close to the road.

  • Selection of clear zones
  • Management of roadside hazards
  • Selection and placement of barriers
  • 1. INTRODUCTION
  • 2. METHOD
    • 2.1. Stakeholder Consultations
    • 2.2. Development of Methodologies
    • 2.3. Data for Investigation of Clear Zones, Roadside Hazards and Barriers
      • 2.3.1. Data Collection and Database Development
      • 2.3.2. In-depth Run-off-road Crash Data
      • 2.3.3. Additional Safety Barrier Data from VicRoads
    • 2.4. Data Analysis
      • 2.4.1. Investigation and Modelling of Clear Zones and the Key Design Parameters
      • 2.4.2. Statistical Modelling of Clear Zone Design Parameters
      • 2.4.3. Analysis of Effects of Shoulders and Roadside Surface on Crash Outcomes
      • 2.4.4. Analysis of Safety Barrier Data
    • 2.5. Review of Technical Standards and Manuals
  • 3. RESULTS
    • 3.1. Stakeholder Consultations
      • 3.1.1. Working Group Terms of Reference
      • 3.1.2. Project Structure
      • 3.1.3. Overview of Stage 1 of the Project
      • 3.1.4. Proposed Project Methodologies for Stage 2
      • 3.1.5. Proposed Project Scope for Stages 3 and 4
      • 3.1.6. Stakeholder Input
    • 3.2. Development of Crash Reconstruction and Simulation Methodology
    • 3.3. Relationship between Clear Zones and Crash Outcomes
      • 3.3.1. Distribution of Clear Zones and Crashes
      • 3.3.2. Safety Performance in Different Clear Zones
      • 3.3.3. Clear Zones and Crash Severity
      • 3.3.4. Safe System Relevance
      • 3.3.5. Angle of Impact in Run-off-road Crashes
    • 3.4. Investigation of the Key Design Parameters Influencing Selection of Clear Zones
      • 3.4.1. Effect of Speed Limit
      • 3.4.2. Effect of Grade
      • 3.4.3. Effect of Section Operating Speed
      • 3.4.4. Effect of Curve Radius
      • 3.4.5. Effect of Batter Slope
      • 3.4.6. Effect of Sealed Pavement Width
      • 3.4.7. Effect of Hazard Density
      • 3.4.8. Summary
    • 3.5. Statistical Modelling of Clear Zone Design Parameters
      • 3.5.1. Analysis of Variables
      • 3.5.2. Selection of Road and Roadside Variables
      • 3.5.3. Association between Road and Roadside Variables and Crashes
      • 3.5.4. Results of Modelling
    • 3.6. Role of Shoulders in Driver Recovery
    • 3.7. The Relationship between Roadside Surface Characteristics and the Extent of Intrusion by Errant Vehicles
    • 3.8. Substitution of Roadside Hazards with Frangible and Impact Absorbing Solutions
      • 3.8.1. Lighting Poles
      • 3.8.2. Sign Posts
      • 3.8.3. Utility Poles
      • 3.8.4. Traffic Signal Poles
      • 3.8.5. Gantry Supports
      • 3.8.6. Crash Performance of Guardrail vs. Other Roadside Hazards
    • 3.9. Selection and Placement of Barriers
      • 3.9.1. Performance of Different Safety Barrier Types
      • 3.9.2. Placement of Barriers
    • 3.10. Selection and Placement of Point Hazard Barriers/Attenuators
      • 3.10.1. Crash Cushions
      • 3.10.2. Point Hazard Barrier Systems
  • 4. DISCUSSION
    • 4.1. Issues Relating to the Results
    • 4.2. Identified Knowledge Gaps
  • Relationship between clear zones and crash outcomes
  • Investigation of the key parameters influencing selection of clear zones
  • Statistical modelling of clear zone design parameters
  • Role of shoulders in driver recovery
  • The relationship between roadside surface characteristics and the degree of intrusion of errant vehicles
  • Substitution of roadside hazards with frangible and impact absorbing solutions
  • Selection and placement of barriers
  • 5. CONCLUSIONS
  • Relationship between clear zones and crash outcomes
  • Investigation of the key parameters influencing selection of clear zones
  • Statistical modelling of clear zone design parameters
  • Role of shoulders in driver recovery
  • The relationship between roadside surface characteristics and the degree of intrusion of errant vehicles
  • Substitution of roadside hazards with frangible and impact absorbing solutions
  • Selection and placement of barriers
  • Selection and placement of point hazard barriers/attenuators
  • Next steps