Road design

Cover of Freeway Design Parameters for Fully Managed Operations
Freeway Design Parameters for Fully Managed Operations
  • Publication no: AP-R341-09
  • ISBN: 978-1-921551-69-7
  • Published: 1 December 2009

Austroads Project NS1375 provides a guide that can be used by road authorities to develop their own set of detailed design guidelines. A guide of this nature is required as current freeway design guidelines are based on design principles established prior to the wide scale application of traffic management tools. With growth in traffic, a need has been identified to more effectively use the existing freeway network in order to better cater for higher traffic flows.

To achieve the project’s objectives it was proposed that the work be undertaken in two phases:

  • Phase 1: a discussion paper on freeway management systems and their impact on freeway design based on Australian and international practice.
  • Phase 2: final report addressing the development of freeway design guidelines for traffic operation and management.

The Austroads project committee determined that the report would focus on the following key freeway management tools:

  • ramp signals
  • lane use management systems (LUMS) including variable speed limits (VSL)
  • shoulder lane use
  • variable message signs (VMS)
  • reversible lanes.

The report also addresses other components of freeway design which affect vehicle throughput in congested conditions.

  • Project Manager
  • General
  • Ramp signals
  • Lane use management systems (LUMS)
  • . Shoulder lane use
    • 10.1. Overview
    • 10.2. Benefits
    • 10.3. Warrants
    • 10.4. Key Freeway Design Principles
      • 10.4.1. Shoulder Lane Use for Specific Vehicles (e.g. Taxis and Buses)
      • 10.4.2. Shoulder Lane Used to Provide Queue Storage for Exits
      • 10.4.3. Shoulder Lane Use for other Isolated Lengths that are not Spanning across Interchanges
      • 10.4.4. Shoulder Lane Use for Extended Length i.e. Across Interchanges
      • 10.4.5. Shoulder Lane Use to Operate on a Full-time or Part-time Basis
      • 10.4.6. Dynamic Lane Markings
      • 10.4.7. Legal Issues
      • 10.4.8. Incident Management
      • 10.4.9. Emergency Refuge Areas
      • 10.4.10. Minimum Standards for the Shoulder Operating as a Trafficable Lane
      • 10.4.11. Bicycle Usage of the Shoulder Lane
      • 10.4.12. Speed Limit Signage
    • 10.5. Example Design Applications
      • 10.5.1. Shoulder Lane Use for Specific Vehicles (e.g. Taxis and Buses)
      • 10.5.2. Shoulder Lane Used to Provide Queue Storage for Exits
  • VMS
  • Reversible lane systems
  • Other
  • 1. INTRODUCTION
  • 2. MANAGED FREEWAYS
    • 2.1. Conventional Freeways
    • 2.2. Managed Freeways
    • 2.3. Managed Freeways in Relation to the Overall Road Network
    • 2.4. Managed Freeway Operations
    • 2.5. Current and Required Guidelines
  • 3. OPERATIONAL OBJECTIVES OF MANAGED FREEWAYS
  • 4. THE NEED FOR AN ITS STRATEGY
  • 5. DATA REQUIREMENTS
    • 5.1. If it Cannot Be Measured, it Cannot Be Managed
      • 5.1.1. Communication of Information to Manage the Freeways
      • 5.1.2. The Use of Information to Respond More Effectively to an Incident
    • 5.2. If it Cannot Be Measured, it Cannot Be Justified
    • 5.3. Types of Data Collection
      • 5.3.1. Intrusive
      • 5.3.2. Non-intrusive
    • 5.4. Spacing and Location of Data Collection Tools
      • 5.4.1. Spacing and Location of In-pavement Detectors
      • 5.4.2. Spacing and Location of CCTV
    • 5.5. Infrastructure Requirements
  • 6. EDUCATION AND COMPLIANCE REQUIREMENTS
    • 6.1. Education
    • 6.2. Compliance
      • 6.2.1. Algorithms
      • 6.2.2. Enforcement
  • 7. CONSIDERATIONS FOR THE DESIGN OF NEW OR UPGRADED FREEWAYS
    • 7.1. Determination of the Strategic Objective of the Road Network
    • 7.2. Understanding of the Freeway System
    • 7.3. Design for Managed Freeways
    • 7.4. Design for the Ultimate
    • 7.5. Complete Corridor Treatments
    • 7.6. When to Apply Management Tools
      • 7.6.1. Measures to Address Corridor-long Issues
      • 7.6.2. Measures to Address Isolated Congestion
    • 7.7. Need to Understand Downstream Impacts (including on the Mainline and Exit Ramps)
  • 8. FREEWAY RAMP SIGNALS
    • 8.1. Overview
    • 8.2. Benefits
    • 8.3. Warrants
    • 8.4. Key Freeway Design Principles
      • 8.4.1. Capacity Analysis
      • 8.4.2. Number of Traffic Lanes at the Stop Line
      • 8.4.3. Ramp Length for Adequate Storage
      • 8.4.4. Catering for Ramp Queue Overflow
      • 8.4.5. Freeway to Freeway Interchanges
      • 8.4.6. Ramp Geometry and Merging Distance – Location of Stop Line
      • 8.4.7. Lane Merging on the Ramp Itself
      • 8.4.8. Bypass Lanes
      • 8.4.9. Shoulders at On-ramp with Ramp Signal Installations
      • 8.4.10. Lane Widths
      • 8.4.11. Key Hardware
      • 8.4.12. Integrated Traffic Control
      • 8.4.13. Ramp Closures
      • 8.4.14. Alternative to Ramp Signals
    • 8.5. Example Design Applications
      • 8.5.1. Typical Ramp Signal Layout
      • 8.5.2. Example Design Applications
  • 9. LANE USE MANAGEMENT SYSTEMS INCLUDING VARIABLE SPEED LIMITS
    • 9.1. Overview
      • 9.1.1. Reversible Lane Systems
      • 9.1.2. VSL/LCS
      • 9.1.3. Non-integrated VSL and LCS (i.e. Separate Displays)
      • 9.1.4. Components of the VSL/LCS
    • 9.2. Benefits
      • 9.2.1. VSL Alone
      • 9.2.2. VSL/LCS
    • 9.3. Warrants
      • 9.3.1. VSL Alone
      • 9.3.2. VSL/LCS
    • 9.4. Key Freeway Design Principles
      • 9.4.1. Mounting Structure
      • 9.4.2. Mounting on Other Infrastructure
      • 9.4.3. Vertical Clearance
      • 9.4.4. Horizontal Clearance
      • 9.4.5. Maintenance Needs
      • 9.4.6. Provision to Mount and Operate Speed Enforcement Devices
      • 9.4.7. Longitudinal Position of VSL/LCS – Open Road Environment
      • 9.4.8. Longitudinal Position of VSL/LCS – Tunnel Environment
      • 9.4.9. Longitudinal Position of Side Mounted VSL Only
      • 9.4.10. Proximity to Other Signage
      • 9.4.11. Consideration for the Application of LUMS at Collector/Distributor Roads
      • 9.4.12. Supporting Static Signage
    • 9.5. Example Design Applications
      • 9.5.1. Gateway Upgrade Project
  • 10. SHOULDER LANE USE
  • 11. TRAVELLER INFORMATION SYSTEM (VARIABLE MESSAGE SIGNS)
    • 11.1. Overview
      • 11.1.1. Text Based VMS
      • 11.1.2. Pictogram in Conjunction with Text VMS
      • 11.1.3. Dedicated Drive Time Information Including Advanced Freeway Information Installed on Arterial Roads
    • 11.2. Benefits
    • 11.3. Warrants
    • 11.4. Key Freeway Design Principles
      • 11.4.1. Mounting Structure
      • 11.4.2. Vertical Clearance
      • 11.4.3. Horizontal Clearance
      • 11.4.4. Maintenance Needs
      • 11.4.5. Size of VMS
      • 11.4.6. Use of Visibility Enhancing Devices
      • 11.4.7. Placement of VMS
      • 11.4.8. VMS Used to Communicate Messages to Drivers of Specific Vehicles
    • 11.5. Example Design Applications
      • 11.5.1. En route Travel Information Systems
      • 11.5.2. VMS Used to Reduce Incidents Associated with Heavy Vehicle Instability on Ramps
      • 11.5.3. Innovative Measures Used to Communicate Messages to Drivers of Specific Vehicles
  • 12. REVERSIBLE LANES
    • 12.1. Overview
    • 12.2. Benefits
    • 12.3. Warrants
    • 12.4. Key Freeway Design Principles
      • 12.4.1. Length (or Strategic Importance)
      • 12.4.2. Location within Cross-section
      • 12.4.3. Lane Widths
      • 12.4.4. Separation
      • 12.4.5. Number of Lanes
      • 12.4.6. Efficient Access
      • 12.4.7. Direct Access
      • 12.4.8. Intermediate Crossovers
      • 12.4.9. Signage
      • 12.4.10. Increased Incident Management
      • 12.4.11. Reversible Lane Systems for Use to Respond to Major Incidents in Key Infrastructure
      • 12.4.12. Other Factors
    • 12.5. Example Design Applications
      • 12.5.1. Temporary Reversible Lane Systems in Response to Incidents on a Section of Freeway
      • 12.5.2. Reversible Lane System Used on General Holmes Drive near the Interchange with the M5 East Freeway – Sydney
  • 13. OTHER CONSIDERATIONS
    • 13.1. Interchange Improvements
      • 13.1.1. Interchange Spacing
      • 13.1.2. Spacing Between the Off-ramp and On-ramps at the Same Interchange
      • 13.1.3. Interchange Type
    • 13.2. Ramp Improvements
      • 13.2.1. Measures Beyond Ramp Signals to Improve Merging
      • 13.2.2. Measures to Improve Traffic Flow at the Off-ramp
    • 13.3. Carriageways
      • 13.3.1. Narrow Lanes
    • 13.4. Priority Facilities
    • 13.5. Turn Around Facilities for Incident Management
    • 13.6. Geometric Issues
      • 13.6.1. Vertical Grades
      • 13.6.2. Right-hand Ramps
      • 13.6.3. Sight Distance
  • 14. FUTURE INVESTIGATIONS
    • 14.1. Dynamic Lane Widths
    • 14.2. Methods Used by Overseas Road Authorities to Improve Mainline Traffic Flow at Interchanges
      • 14.2.1. Tiger-tailed Ghost Island
      • 14.2.2. The Use of Modified Lane Line Marking
  • 15. IMPACT OF FREEWAY MANAGEMENT TOOLS ON DESIGN PARAMETERS
    • 15.1. Carriageway
    • 15.2. Ramps
    • 15.3. Interchanges
  • Cross-sectional impacts
  • Longitudinal impacts
  • Ramp length and width
  • Ramp nose
  • 16. KEY PRINCIPLES
  • Ramp signals
  • Lane use management systems (LUMS)
  • Shoulder lane use
  • VMS
  • Reversible lane systems
  • Other
  • REFERENCES