Speeding

Most drivers are familiar with road safety campaigns and enforcement to reduce speeding. But they might not know the reasons behind these activities. We've put together answers to some of the common queries on speeding issues.

Is speed really a road safety problem?

It's difficult in hindsight to determine the contribution speed has made in a crash. However, it's estimated that speed is a factor in around 1 in 5 serious crashes. This increases to around 40% for fatal crashes.

While speeding may not necessarily be the primary cause of all crashes, it's influence may be enough to instigate a crash or worsen the outcome.

Speeding is not necessarily just an issue of exceeding the speed limit. It also includes driving at speeds inappropriate for the conditions, even well below the speed limit.

Does a small amount over the speed limit really matter?

• From a legal point of view the law is clear - the speed limit is the speed limit and exceeding it is breaking the law. From a safety point of view, it's not as clear cut.
• Driving at any speed, even under the speed limit, has some level of risk. Many people think that going a small amount over the speed limit doesn't greatly increase the level of risk. However, research suggests that travelling at 65 km/h in a 60 km/h zone doubles your chance of having a crash that injures someone. At 70 km/h, the risk increases 11 times.
• It's important that speed limits are set at a level appropriate for the conditions and at a speed most motorists will comfortably drive. To reduce the risk of a crash, motorists should not exceed this limit.

Who sets speed limits and how are they set?

The setting of speed limits involves balancing mobility desires and needs (moving with reduced delay), safety (keeping risks as low as possible or acceptable) and amenity (other impacts on the community). Any speed limit is a compromise between these factors. Authorities decide to give a greater bias towards safety and amenity on some roads, such as local residential streets or high pedestrian activity areas, with more emphasis on lower speed limits and mobility in other areas.

Some of the factors that come into consideration include the history of crashes and casualties along a road, how many 'conflicts' there are with moving traffic (such as access points and traffic controls), the road alignment and the use of the land on either side of the road. Traffic authorities have guidelines established to match road conditions with speed limits.

In NSW and the ACT, the relevant authorities are the NSW Roads and Traffic Authority and the ACT Department of Urban Services.

Have road and vehicle improvements made high speed driving safer?

• To an extent, yes. However, speeding continues to be identified as a contributing factor in over 200 fatal crashes and 3,000 serious injury crashes across NSW and the ACT every year. Cars also still require significant distances to stop and rely on us - the drivers - to detect and react to hazards.
• Many people are surprised to hear how long it actually takes to bring a car to a stop. Driving at 60 km/h, it takes an alert motorist around 46 metres to perceive, react and brake to a stop on a dry road or 55 metres on a wet road. That's longer than an Olympic sized swimming pool. Remove driver alertness or add distractions and this distance increases by about 50%.
• At 60 km/h, a vehicle travels 17 metres every second - close to the length of a cricket pitch. At 100 km/h this increases to 28 metres.
• However, it's important to remember that stopping distances increase at a higher rate than the speed increase. For example, even though 80 km/h is 33% faster than 60 km/h, the stopping distance increases by nearly 70%.

Kloeden CN, McLean AJ, Moore VM, and Ponte G. Travelling Speed and the Risk of Crash Involvement. NHMRC Road Accident Research Unit, The University of Adelaide, 1997.