Table of Contents

Appendix A 2 The Safe System Approach

Both Australia’s National Road Safety Strategy 2011–2020 (ATC 2011) and New Zealand’s Road Safety Strategy, Safer Journeys 2010–2020, (Ministry of Transport 2010a) adopt the Safe System approach as their guiding principle. The Safe System approach and principles is also discussed in the Guide to Road Safety Part 1 (Austroads 2013). The Safe System differs from traditional approaches to road safety. Rather than always blaming the road user for causing a crash, it acknowledges that even responsible people sometimes make mistakes in their use of the roads.

Safe System principles require a holistic view of the road transport system and the interactions among roads and roadsides, travel speeds, vehicles and road users. This is an inclusive approach that caters for all groups using the road system, including drivers, motorcyclists, passengers, pedestrians, bicyclists, and commercial and heavy vehicle drivers.

The Safe System approach is built on three basic principles (ATC 2011):

  1. People make mistakes. Humans will continue to make mistakes, and the transport system must accommodate these. The transport system should not result in death or serious injury as a consequence of errors on the roads.
  2. Human physical frailty. There are known physical limits to the amount of force our bodies can take before we are injured.
  3. A ‘forgiving’ road transport system. A Safe System ensures that the forces in collisions do not exceed the limits of human tolerance. Speeds must be managed so that humans are not exposed to impact forces beyond their physical tolerance. System designers and operators need to take into account the limits of the human body in designing and maintaining roads, vehicles and speeds.

‘The Safe System focuses on creating safe roads, safe speeds, safe vehicles and safe road use’ (Ministry of Transport 2010a). The ultimate goal of a Safe System would be to achieve:

  • Safe roads – that are predictable and forgiving of mistakes. They are self-explaining in that their design encourages safe travel speeds.
  • Safe speeds – travel speeds suit the function and level of safety of the road. People understand and comply with the speed limits and drive to the conditions.
  • Safe vehicles – that prevent crashes and protect road users, including pedestrians and cyclists, in the event of a crash.
  • Safe road use – road users that are skilled and competent, alert and unimpaired. They comply with road rules, take steps to improve safety, and demand and expect safety improvements (Ministry of Transport 2010a).

To achieve these goals, ‘the human body’s tolerance to crash forces will need to be the key design factor for the system. Crash forces would be managed so they do not exceed these limits’ (Ministry of Transport 2010a).

The system is shown diagrammatically in Figure A 1. The central consideration is to ensure that under no circumstances are road users exposed to greater physical forces than they can withstand without serious damage. In principle, this may be achieved in a number of ways, most obviously by reducing speeds. However, to rely on reducing speeds on its own would require very low speeds, quite possibly lower than the public would be prepared to accept. In practice, the goal of tolerable forces is sought through a combination of measures e.g. improved crashworthiness and protective equipment in vehicles along with protective barriers to deal with run-off-the-road crashes.

Figure A 1: A conceptual overview of the Safe System framework

Source: ATC (2009).

Under this framework, the essential tasks of road safety management are:

  • determining the relevant risk factors in a given situation
  • determining which risk factors can be effectively manipulated
  • determining which countermeasures will produce the desired outcomes, then applying them effectively.

The framework is flexible enough that it can be used to guide overall policy settings (e.g. speed limits for roads with a particular function, given the characteristics of the vehicle fleet in terms of occupant and pedestrian protection), yet still apply at the level of individual projects (e.g. determining the most suitable type of barrier given the characteristics of the vehicle fleet and the estimated operating speeds at a particular location).