Speed management is critical to road safety, supported by the Movement and Place approach. This includes setting safe and appropriate speed limits, ensuring compliance and setting policies and using vehicle safety technology to alert drivers to their travel speed.
Speed is a critical element in the Safe System because it affects the ability to avoid a crash or reduce its physical impact. Without vehicle movement (speed), there would be no crashes. All parts of the Safe System play an important role in managing speed and achieving safety outcomes.
An integrated speed management approach includes a range of different measures working together:
- Setting appropriate speed limits for safety, mobility and place
- Road design and road safety engineering treatments
- Enforcing speed limits
- Influencing behaviour and road safety norms through public education
- Vehicle technologies to support compliance and limit speeding
- Workplace road safety policies.
Road authorities are increasingly transitioning from traditional road classification systems to adopt the Movement and Place approach, recognising the design of streets should work to maximise safe access for people.
Across Australia, many roads do not conform to newer Safe System guidelines prioritising injury prevention, often referred to as our ‘legacy network’. Speed limit adjustments have a role to play in addressing risk when roads do not have the features required to prevent crashes or reduce their severity. Before this can be considered, there must be a level of community understanding about what makes a road safe and the limitations of funding to retrofit the whole network with safety features. Without both social licence and enforcement, compliance with reduced speed limits may be limited.
Speeding is motorists travelling above the posted limit or not driving to conditions. Many people believe they “speed safely” and others speed dangerously. The truth is everybody who speeds endangers not only themselves, but also passengers and other road users sharing the network. Speeding can be a single contributing factor of a fatal chain of events or can heighten the consequences of other errors.
Greater community understanding of risks associated with speeding is needed, leading to a social license to support speed enforcement, and where appropriate, establishing Safe System speed limits as credible road safety solutions.
The Movement and Place approach
The way we design our roads and streets determines people’s quality of life, interactions and experiences. The Movement and Place approach recognises roads and streets serve dual functions as essential corridors for moving people and goods, and important public spaces where life unfolds. Taking a Movement and Place approach supports the delivery of a Safe System. The Movement and Place approach informs road design, and considers speed management to reduce road trauma in urban, regional and remote communities.
Movement and Place provides guidance in how to prioritise and integrate movement; improve liveability; create vibrant streets attracting greater numbers of cyclists and pedestrians; and reduce the risk of exposure to death and serious injuries on the whole network. It helps governments to create successful and safe streets and roads by balancing the movement of people and goods with the amenity and quality of places.
A key principle of road design is the “self-explaining road”, an environment which encourages safe behaviour simply by its design. It uses simplicity and consistency of design so road users can easily comprehend the type of road and what is expected of their driving, reducing driver stress and driver error. For example, in low speed limit areas the road may be narrower, automatically encouraging drivers to slow down.
Movement and Place accounts for meeting the different functions of roads to varying degrees. Motorways and movement corridors provide for fast movement with little or no ‘place’ function, whereas in vibrant streets, local streets, and places for people (e.g. low speed shared zones) the emphasis is on slow movement, and place is the primary consideration. This approach informs speed management and road design and is critical to the decisions we make, including those on speed management.
Source: Austroads, 2020. Research Report AP-R611-20 Integrating Safe System and Movement and Place for Vulnerable Road Users; Austroads, AP-R560-18 Towards Safe System Infrastructure: A Compendium of Current Knowledge.
Setting speed limits
Setting appropriate speed limits is a critical component of road safety. The speed limit must take into account the standard and condition of the road, the function the road performs and level of safety to all road users, traffic volumes and the environment. Many roads in Australia subject to the default speed limit (i.e. 100 km/h) are not safe for a speed limit that high. A number of roads in regional and remote areas are undivided, single carriageways where there is a risk of head-on crashes, and the default speed limit typically applies. These roads have been found to consistently have a much higher proportion of crash deaths than other roads, and some may even be posted with higher limits, for example 110 km/h.
Impact speed has a significant correlation to the risk of serious injury across different crash types, with head-on impacts carrying more risk at lower speeds. Graph 1 below illustrates how different crash types carry more risk of serious injury even at lower speeds.
The risk of serious injury reaches 1 per cent at 28 km/h for head-on impacts, 51 km/h for side impacts, 64 km/h for front impacts, and 67 km/h for rear impacts in light vehicle crashes, showing the importance of prioritising the prevention of head-on crashes. At higher speeds, the different crash types maintain these profiles, with head-on impacts rising to an increased likelihood of serious injury of 50 per cent at 76 km/h, where side impacts carry the same risk of serious injury at 90 km/h, rear impacts at 108 km/h, and front impacts at 148 km/h.
Graph 1 – Comparison of impact speed risk curves
Source: Doecke S.D et al., Impact speed and the risk of serious injury in vehicle crashes (2020).
Special speed limits are set in areas where there is a particular risk to vulnerable road users. These include school zones (40 km/h or lower during school times) and areas of high pedestrian activity.
All states and territories have implemented 40 km/h speed limits in areas with high pedestrian and bicycle use and some states have introduced 30 km/h or lower speed limits in certain areas. For example, South Australia has a fairly consistent application of 25 km/h in school zones and the ACT has 20 km/h in the CBD’s high pedestrian activity area. Infrastructure treatments reduce vehicle speeds at points of conflict in intersections, including roundabouts and intersection platforms, which reduce vehicle speeds at the entry point. These have proven to be effective in reducing fatalities and serious injuries.
Road design and road safety engineering
The design of the road and specific road treatments have an important role in supporting compliance with speed limits. For lower-speed limits this includes traffic calming treatments such as narrowed driving lanes, and threshold treatments where the road colour and/or texture changes to indicate a changed driving environment. Infrastructure treatments reduce vehicle speeds at points of conflict in intersections such as installing roundabouts and intersection platforms, which reduce vehicle speeds at the entry point. These have proven to be effective in reducing fatalities and serious injuries. Consistent with the self-explaining road principle, good road design will help to achieve the desired driving behaviour/speed choices naturally, as opposed to simply changing the speed limit signs which may be less effective.
Monitoring, detection and enforcement programs are key to increasing compliance with speed limits. Speed enforcement is an important element of an integrated speed management approach. It changes road user behaviour and helps to ensure drivers do not exceed posted speed limits, resulting in fewer crashes and reduced road trauma. To maximise its effect, speed enforcement is best supported by other measures such as credible and appropriate speed limits and public education enhancing knowledge of the dangers of speeding and strengthening community support for speed enforcement. Best practice speed enforcement strategies will draw on a combination of fixed speed cameras; mobile speed cameras; point to point speed cameras; and covert and/or overt on road police presence.
Deterrence theory is the driving force for enforcement programs, including those targeting speed. Individuals will avoid offending if they fear the consequences and perceive they will be caught. Deterrence can be specific (once sanctions are personally experienced people are less likely to re-offend) or general (the public will avoid the targeted behaviour once they have seen or learned about the possible consequences and the likelihood of being caught).
General deterrence is most strongly achieved with ‘anywhere, anytime’ enforcement, encouraging all road users to maintain speeds within the maximum posted limit.
Education and cultural change
Long-term cultural change is needed to make road safety ‘business as usual’, including through reducing community acceptance of speeding. The National Road Safety Strategy is taking a social model approach in its delivery, which will leverage influence at all levels of society to bring about cultural change.
While enforcement contributes to compliance with speed limits, education and cultural change is needed to reduce speeding in Australia, including developing a greater understanding of the risks and consequences associated with ‘everyday’ behaviours: The risk of involvement in a fatal crash doubles with every 5 km/h increase in speed over the limit in a 60 km/h zone.
There is also a need to build greater understanding and awareness of the physics associated with speed, with community acceptance for applying speed limit reductions on high risk roads, including in regional and remote areas. Education of risks associated with speed includes through advertising, driver education programs, school education programs and raising social awareness through the influence of colleagues, friends and families to bring about behavioural change.
Vehicle safety technology and speed
Vehicle safety technologies designed to assist drivers in managing their speed and keeping within the posted speed limits are becoming increasingly available in new cars. These include:
- Speed alert alarm systems alerting a driver when the vehicle exceeds a pre-set speed.
- Intelligent Speed Assist, determining the speed limit of the vehicle’s location and alerting the driver if they are over that limit.
- Top speed limiters, which stop a vehicle from travelling above a set speed for an extended time.
Workplace road safety policies
Workplace road safety policies set guidelines around road use for employees. For example, some organisations set speed limits for their vehicle fleet (such as mining and trucking organisations), while others ensure the use of safe vehicles and safety technologies through their corporate fleet purchases. Organisations may also set employee policies relating to illegal road behaviour, including speeding and other behaviour such as mobile phone use while driving.
These policies can in turn have an influencing effect, encouraging safe road behaviours outside of the workplace.