The Challenge

Inappropriate or excessive speed is a major road safety issue. Effective speed management is fundamental and critical to reducing speed-related road trauma. 

Speed limit setting is at the core of speed management. Speed limits need to be set at a safe and appropriate level, considering the function, design and safety of the road. Infrastructure Risk Rating (IRR), initially developed in New Zealand, is a simple road assessment methodology designed to assess road safety risk at a network level, primarily as an input to the speed limit setting process. 

Following the successful development and application of IRR of in New Zealand, Austroads sought to better understand how IRR could also be applied in Australia for speed management purposes. In addition, Austroads commissioned Abley to identify case studies of good practice and compile good practice on stakeholder and community engagement as part of the effective implementation of speed management interventions.

The Solution

The research methodology included a desktop literature review and consultation with state jurisdictions in Australia to source examples and learnings from recent speed management interventions.  

Four IRR trials were undertaken across a range of road environments to test the applicability of IRR for Australian roads. It was found that IRR is a strong predictor of road risk on rural roads and is a robust predictor of pedestrian and cycle risk on urban roads. Including a ‘speed risk factor’ as a proxy for operating speed also enhanced the IRR model in Australia. 

web tool and coding manual was developed from the research findings to help practitioners calculate the IRR of any section of road in Australia. A workshop tour of Australian state capitals was train practitioners on IRR and the use of the IRR tool for speed management purposes. 

Finally, representatives from Australian jurisdictions were interviewed to identify a range of good practice speed management case studies. Extensive good practice guidance on engagement and consultation strategies was also developed. 

The output of this project is Austroads report AP-R587-19 “Road Risk Assessment, Case Studies and Engagement Guidance for Speed Management”. A webinar on this report was also released and can be viewed on the Austroads' website.

The Outcome

The research findings and IRR tool will help road authorities across Australia to assess their road network and identify appropriate speed limits and effective speed management interventions. The IRR tool will be of particular benefit to local authorities where funding constraints limit the use of existing more complex risk assessment tools.