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Speed and road safety

The effect of speed in road accidents and associated injuries and fatalities

Effects of speeding

Speed is a factor in all road deaths and injuries. In Victoria, one third of all road casualties are caused by speeding, with about 100 people killed each year, and another 2,000 seriously injured.

By reducing speed, the likelihood of surviving or avoiding injury is far greater. On the flip side, the chances of being in a crash double for every 5 km/h over the limit you drive in a 60 km/h zone.

Research shows that for every one per cent reduction in speed, there is a three per cent reduction in casualty crashes. These findings underpin the Transport Accident Commission’s ‘Wipe off 5’ campaign and encourage drivers to stick to specified Speed limits.

Crash physics

Kinetic energy increases rapidly as speed increases and is the cause of human injuries or death in a crash. By doubling the speed a vehicle is travelling, the amount of kinetic energy more than doubles, with a 20 per cent increase in speed increasing kinetic energy by around 45 percent.

Chances of survival

Studies from the Monash University Accident Research Centre show that a small rise in speed substantially increases the risk of death or serious injury. A person hit by a car travelling at 30 km/h will be severely injured and have a 10 per cent likelihood of death. If the speed increases to 55km/h, the likelihood of death is about 85 per cent, and at 60km/h the person is unlikely to survive.

Based on data cited in Monash University Accident Research Centre Report 229 (figure 3.5)

Survival rates are higher for car occupants than pedestrians. Even so, a side impact above 40 or 50 km/h and a front impact above 70 km/h are likely to cause death, although having airbags fitted greatly increases your chance of survival.

Encouraging drivers to reduce their driving speed by just a few kilometres per hour will substantially reduce both the number and severity of road casualties.

Vulnerable road users

Pedestrians, cyclists and motorcyclists are the most vulnerable of all road users. A small reduction in vehicle speed could save their life in a collision.

Although there is an argument that modern cars are safer and have better technology to offset the effects of speeding, this is generally not to the benefit of vulnerable road users. No technology can completely overcome the laws of physics in terms of stopping distances or the severity of impact.

sheriff wheel clamped to car wheel

Hoon driving

Anti-hoon laws in Victoria give police the power to impound, immobilise or permanently confiscate vehicles.

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Police enforcement

Enforcement agencies like Victoria Police play an important role in promoting safe road use, changing driving behaviour and helping to reduce the amount of deaths on our roads.

The speed limit indicates the maximum legal speed

Speed limits

The speed limit indicates the maximum legal speed, but by reducing speed, drivers can help decrease the number of road incidents.

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