Effects of Speeding

The Real Impact of Speeding on Australian Roads

Speeding is considered one of the ‘fatal five’ causes of major car accidents on Australian roads. Between 2012 and 2016 speeding was recorded as the primary cause of 31% of road deaths across all states which monitor behavioural causes of fatal accidents.

However, this statistic under-emphasises the toll that speeding takes on Australian lives every year. Vehicle speed is typically a fatal factor even when other dangerous behaviours like phone distraction or driving under the influence are recorded as the primary cause of the accident.

Despite the well known dangers of speeding, it remains a persistent problem on Australian roads, and the proportion of accident deaths from speeding are even increasing in some states.

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What is speeding?

The answer to this question may seem obvious – driving fast. However, speeding involves more than just high speed driving, and failure to understand this can perpetuate unsafe driving behaviours.

Speeding is any driving behaviour that falls into one of the following three categories:

  • excessive speed, or high speed driving which is above the maximum national speed limit
  • exceeding the speed limit, defined as travelling 5 km/h or more above the posted speed limit on any road
  • travelling at a speed which is inappropriate to conditions – such as reduced visibility and poor road conditions.

Why speeding is dangerous

There are a number of reasons why speeding causes such severe accidents.

The first is that the faster you’re going, the more distance you’ll require to bring your car to a complete stop in an emergency. According to the Transport Accident Commission of Victoria, a car travelling 50 km/h requires approximately 35 meters to come to stop, taking both driver reaction time and braking distance into account.

Every additional 5 km/h in speed increases the required stopping  distance by around 5 meters.  What this means in practice is that cars travelling at higher speeds are less likely to be able to stop in time to avoid a collision. They will also be travelling at higher speeds at the point of collision, even if the driver reacts and breaks promptly.

The second reason why speeding is dangerous is that it increases the risk of losing control of a vehicle if the driver swerves to avoid a collision or brakes hard. The higher the speed the greater the likelihood that the vehicle’s tyres will lose traction, causing the driver to lose control of the car’s steering, usually with catastrophic consequences.

In combination these factors rapidly drive up the risk of suffering severe injury or death for even minor increases in speed. Using real crash statistics, scientists at the University of Adelaide calculated that the risk of becoming a casualty in an accident doubles every time a car’s speed increases by 5km/h above 60km/h. This means risk is quadrupled for a car travelling at 70 km/h compared to one travelling at 60 km/h.

The deadly effects of collisions

At the moment of collision a speeding car subjects occupants to enormous gravitational forces (or g forces). A car that collides with an object in front of it while travelling at 50 km/h will subject car occupants wearing seatbelts to around 30 g’s of force.

This is equivalent to the impact created by dropping the same car out of a three storey building.

At 100 km/h the force of an impact is equivalent to what the car would experience if you drove it off the roof of a 12 storey building. These forces are so extreme that they can cause fatal internal injuries even if a car occupant does not strike any part of the car during the collision.

It should go without saying that speeding accidents are even deadlier for car occupants who are not wearing seatbelts. A car occupant not wearing a seatbelt will experience impact forces of around 150 g’s at just 50 km/h, a force which is typically fatal.

Speeding fatality statistics in Australia

Behavioural causes of accidents, such as speeding, fatigue and distraction are not collected at accident scenes in some Australian states and territories. Therefore a complete picture of speeding related road fatalities is not available at a national level.

Instead data collected by those states and territories that do record behavioural causes of accidents can be used to paint a picture of the toll that speeding takes on Australian lives every year. The following table breaks down the percentage of road deaths attributed to speeding in states which recorded behavioural factors in fatal accidents between 2012 and 2016.

New South Wales40%42%41%41%41%41%
Northern Territory32%21%28%30%15%25%
Western Australia24%22%29%36%33%29%

These statistics paint a grim picture of the effects of speeding on the Australian road toll. Speeding claims a large proportion of all road deaths in these states every year, while the proportion of speeding related road deaths is either steady or increasing in many. This suggests that efforts to reduce some other fatal road behaviours have been successful relative to anti-speeding initiatives.

What this means for you

Speeding is one of the easiest of the ‘fatal five’ risky driving behaviours to avoid. Careful driving, adhering to posted speed limits, observing sensible following distances and developing situational awareness should all reduce your risk of involvement in a dangerous speeding related accident.

By reducing the speed at which you drive you’ll typically also correct some other bad driving habits. For example, you’ll have more time to brake, which means less harsh braking. You’ll also take bends at lower speeds, so you’re less likely to come off the road on a curve. Driving at sensible speeds should also result in less aggressive acceleration and lower fuel consumption.

And when you drive with your own safety in mind, you also make the roads safer for everyone else.

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