Road Safety

This report aims to build evidence to support Austroads’ members in assessing speed limit reductions in lower speed, typically in urban contexts. It is part of the Austroads project SAG6371 Keeping People Safe When Walking program, which aims to help chart a path to zero pedestrian serious trauma.

The assessment applies a cost-benefit analysis (CBA) approach that estimates, monetises and compares the costs (or disbenefits) and benefits for the society from 12 different hypothetical speed limit reductions in a variety of (mostly urban) contexts. In doing so, it helps identify whether there is a strong case for safer speed limits in these contexts, the key drivers of outcomes and areas where further evidence and data would add value.

All 12 tested scenarios had a benefit-cost ratio of more than one ― which means the benefits for society from reduced road trauma and improved pedestrian mobility outweighed the productivity-related costs from increased travel time. The analysis therefore suggests a strong economic rationale for speed limit reductions in a range of urban settings where pedestrians are likely to be affected.

Unsurprisingly, a key driver of outcomes was found to be the starting level of crash risk on a road, which affects the reduction in crashes that can be achieved with a reduction in speed. However, speed limit reductions can also affect the amenity and movement of pedestrians. And these additional benefits for pedestrian can be large in some contexts even when compared to travel time impacts for motorists. The findings were sensitive to the assumptions made with respect to traffic flow and the degree to which motorists travel time may be impeded by other factors, such as intersections and junctions.

On the basis of these findings, the report recommends area where jurisdictions should consider building better data and evidence to allow for more refined analysis of speed limit reductions in the future.

About the project:

Austroads' Keeping People Safe When Walking project envisions a road and street network that places pedestrian safety at its core—regardless of age, race, gender, socioeconomic background, or physical ability. The project supports both national and local efforts to achieve Vision Zero targets: a 50% reduction in pedestrian fatalities and serious injuries by 2030, and their complete elimination by 2050.

To realise this vision, the project draws on data-driven insights to better understand pedestrian trauma and inform impactful interventions across the Safe System.

This report is part of the Stream 2 of the project. Other outputs published as part of this project include:

1. Keeping People Safe when Walking – Stream 1: Pedestrian Safety Problem and Project Methodology
2. Keeping People Safe when Walking – Stream 1: Literature Review
3. Keeping People Safe when Walking – Stream 1: Pedestrian Data Improvement Recommendations
4. Keeping People Safe when Walking – Stream 1: Recommended Pedestrian Safety Interventions
5. Keeping People Safe When Walking – Stream 2: Economic Assessment of Safer Speeds [this report]
6. Keeping People Safe When Walking – Stream 2: Understanding Inequity in Pedestrian Safety Outcomes
7. Keeping People Safe When Walking – Stream 2: Strengthening Key Practitioner Guidance and Methodologies

Webinar:

Watch a recording of the webinar to learn more about this report.