Road Safety
- Publication no: AGRS03-21
- ISBN: 978-1-922382-61-0
- Published: 16 July 2021
- Edition: 1.0
- PDF (free) Download
Austroads' Guide to Road Safety has been developed to provide an overview of road safety and road safety practices in Australia and New Zealand.
Part 3 provides an overview of speed limits and their application as a speed management tool. The use of appropriate speed limits forms an integral part of a safe road system. They are a speed management tool used to improve road safety, while maintaining the efficiency of the road network.
Within the context of a safe road system, speed limits need to reflect the varying types of road users, the road environment, types of vehicles driven and the safety, amenity and economic needs of the community.
The general philosophy adopted when setting speed limits is that when they are being assessed they take into consideration a comprehensive range of factors. These factors include the safety record of the road, the road’s operating performance, the road and roadside infrastructure, geometry and roadside development.
This Guide is intended for road authorities to use when considering a speed limit change or preparing a speed management policy. The guide will also be useful to road safety practitioners who are investigating speed limit changes as part of a solution to a road safety problem. Speed management is so fundamental to the Safe System approach that this Guide should be read in conjunction with all other parts of the Guide to Road Safety.
At the time of publication, the 2021-2030 National Road Safety Strategy has not yet been released. A future project will update this Guide so that it reflects the Strategy.
- 1. Introduction
- 1.1 Purpose of the Guide
- 1.2 Why is Speed Management Important?
- 1.3 Speed and the Safe System
- 2. Speed and Harm
- 2.1 The Association Between Impact Speed and Injury
- 2.1.1 Stopping distance
- 2.1.2 Energy transfer
- 2.1.3 Safe System speeds
- 2.1.4 Further insights on speed and injury severity
- 2.1 The Association Between Impact Speed and Injury
- 3. Speed Behaviour on Roads
- 3.1 Range of Speeds on the Road Network
- 3.2 Complications in Perceiving Speed Risk
- 4. The Case for Safer Speeds
- 4.1 Nilsson’s power model
- 4.2 Kloeden Curves
- 4.3 Evidence from Speed Limit Reductions
- 4.4 The Case for Addressing Low Level Speeding
- 4.5 Travel Time and Productivity
- 5. Ways to Manage Speed
- 5.1 Roads and Roadside Infrastructure
- 5.2 Speed Limits and Speed Enforcement
- 5.3 People
- 5.3.1 Personal factors
- 5.3.2 Legal factors
- 5.3.3 Situational factors
- 5.3.4 Social factors
- 5.3.5 Implementation intentions and pledges to counter speeding
- 5.3.6 People’s attitudes towards speeding
- 5.3.7 What does the community think about speed risks and speed management?
- 6. Types of Speed Limit
- 6.1 Default Speed Limits
- 6.2 Signed Speed Limits
- 7. How Do You Choose the Speed Limit?
- 7.1 Crash Risk
- 7.2 Current Operating Performance
- 7.3 Road and Roadside Infrastructure, Geometry and Roadside Development
- 7.4 Unsealed Roads
- 8. Safe Speed for Regional and Remote Areas
- 8.1 Speed Limits
- 8.2 Engineering Treatments
- 8.3 Enforcing Safe Speeds
- 8.4 Vehicle Countermeasures - ISA
- References
- Appendix A Meaning of the 85th Percentile Speed
- A.1 Driver Selection of Safe (or Optimum) Speeds
- A.2 Speed Dispersion