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Cover of Managing Over-height Vehicles in Tunnels
Managing Over-height Vehicles in Tunnels
  • Publication no: AP-R770-26
  • ISBN: 978-1-923617-63-6
  • Published: 10 August 2026

The purpose of this report is to support the development of enhanced guidance for the management of over-height vehicles on the road network that are at risk of entering managed tunnels. The research identifies opportunities to improve Austroads guidance to support more consistent and effective incident management across jurisdictions.

Over-height vehicle (OHV) incidents continue to present safety, operational and asset protection risks in tunnel environments across Australia and New Zealand. Investment in improved system design, detection technologies and operational practices is key to enhancing safety, efficiency and operational resilience across the network.

Stakeholder engagement and a review of Australian, New Zealand and international literature identified gaps in current practice and opportunities to align with best practice.

Findings indicate that no single solution addresses all problems related to OHV incidents. New technologies and treatments offer clear opportunities, but implementation of these requires planning and testing in local operating environments.

The research identifies opportunities to enhance Austroads guidance to support more consistent and effective incident management across jurisdictions.

  • Summary
  • 1. Introduction
    • 1.1 Purpose
    • 1.2 Scope
    • 1.3 Methodology
      • 1.3.1 Focus inputs for this research
      • 1.3.2 Understanding OHV incidents in tunnels
      • 1.3.3 Planning for OHV incident management
      • 1.3.4 Establishing a baseline of current practices across Australia and New Zealand
      • 1.3.5 Identification of enhancement opportunities and considerations for uplift
    • 1.4 Key actors, roles and responsibilities
    • 1.5 Key terms and definitions
      • 1.5.1 Tunnel
      • 1.5.2 Incident
      • 1.5.3 Over-height vehicle
      • 1.5.4 OHV system
    • 1.6 Acronyms
  • 2. Report Inputs
    • 2.1 Literature review
      • 2.1.1 Governance of tunnel planning and operations in Australia and New Zealand
      • 2.1.2 Existing Austroads guidance
      • 2.1.3 OHT Taskforce findings
    • 2.2 Stakeholder consultation
      • 2.2.1 Austroads Road Tunnels Taskforce
      • 2.2.2 Questionnaire
      • 2.2.3 Interviews
    • 2.3 Existing treatments and incident data
      • 2.3.1 Data limitations
  • 3. Understanding OHV Incidents
    • 3.1 Themes impacting likelihood and severity of OHV incidents
      • 3.1.1 Stakeholder-identified limitations
      • 3.1.2 Key contributors
      • 3.1.3 Variation in OHV incident frequency across tunnels
    • 3.2 Consequences of OHV incidents
    • 3.3 Rate of OHV incidents in Australia and New Zealand
      • 3.3.1 NSW rate of incidents
      • 3.3.2 New Zealand rate of incidents
      • 3.3.3 Incident classification
  • 4. Planning for OHV Incidents
    • 4.1 Systems engineering
      • 4.1.1 V-model outcomes for OHV planning
      • 4.1.2 Stakeholder needs
      • 4.1.3 ConOps
      • 4.1.4 Project specifications
      • 4.1.5 Changes and upgrades
    • 4.2 Operational practices and procedures
  • 5. Managing OHV Incidents in Australia and New Zealand
    • 5.1 Functions of an OHV system
      • 5.1.1 OHV incident lifecycle and functional stages
      • 5.1.2 Typical OHV treatments and technologies
      • 5.1.3 Defining the baseline
      • 5.1.4 Current treatments used in Australia and New Zealand
    • 5.2 Operational environment for incident management
      • 5.2.1 Level of automation
      • 5.2.2 Cross-agency collaboration and integration
      • 5.2.3 Tunnel operator response plans
      • 5.2.4 Road operator network disruption plans
      • 5.2.5 Traffic incident management procedures
      • 5.2.6 Post-incident procedures
  • 6. Opportunity for Enhancements
    • 6.1 Enhancing prevention measures to improve diversion outcomes
      • 6.1.1 Clear and consistent static warning signs
      • 6.1.2 Well-located signage at decision points
      • 6.1.3 Enhancing VMS messaging to better target OHV
      • 6.1.4 Providing adequate time for diversion
      • 6.1.5 Audible alerts and complementary communication measures
    • 6.2 Improving detection and verification
      • 6.2.1 Earlier detection
      • 6.2.2 Enhanced detection for better decision-making
    • 6.3 Mitigating the impact of incidents
      • 6.3.1 Upgrade VSLS to incorporate lane control
      • 6.3.2 Driver communication at portal or stopping point
      • 6.3.3 Retrofitting tunnels with pull-over and turn-around facilities
      • 6.3.4 Use of strike barriers
    • 6.4 Improving the response and recovery time
    • 6.5 Behavioural and enforcement related measures
      • 6.5.1 Enhance driver awareness through pre-trip checks
      • 6.5.2 Enforcement, education, and driver training
  • 7. Implementation Considerations
    • 7.1 A holistic approach to uplift
      • 7.1.1 Post incident analysis to inform process and design upgrades
      • 7.1.2 Information sharing and collaboration
    • 7.2 Uplifting legacy tunnels
      • 7.2.1 Evaluate performance to prioritise treatments
      • 7.2.2 Decision-making framework for OHV system uplift
    • 7.3 Best practice for new tunnels
  • 8. Uplifting Austroads Guidance
  • 9. Conclusion
  • References
  • Appendix A Design and Operations Governance
    • A.1 Tunnels design and operations governance in Australia and New Zealand
  • Appendix B Detailed Austroads Guidance Review
    • B.1 Austroads Guide to Road Tunnels
    • B.2 Jurisdictional supplements to AGRT
    • B.3 Complementary Austroads Guides to AGRT
      • B.3.1 Austroads Guide to Smart Motorways
      • B.3.2 Austroads Guide to Traffic Management
    • B.4 Key Austroads research reports
  • Appendix C Stakeholder Engagement Summary
  • Appendix D Key Actors and Actions Across the Stages of a Typical OHV Incident
  • Appendix E Treatment Catalogue
  • Appendix F Australia and New Zealand Tunnels Treatments and Incident Data
    • F.1 Australia and New Zealand tunnels and treatments
    • F.2 Australia and New Zealand tunnels incident data
  • Appendix G Australia and New Zealand Tunnel Specification Excerpts
  • Appendix H Typical Response Plan for an OHV Incident
  • Appendix I Case Studies
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