In a 60 km/h speed limit area, the risk of involvement in a casualty crash doubles with each 5 km/h increase in travelling speed above 60 km/h.

Speeding in an urban area is as dangerous as driving with an illegal blood alcohol concentration. Even travelling at 5 km/h above the 60 km/h limit increases the risk of crash involvement as much as driving with a blood alcohol concentration of 0.05.

In this study the free speed casualty crashes occurred almost entirely on main roads. There is a compelling case for a lower speed limit throughout urban areas, particularly on arterial roads. Most motorised countries have an urban area speed limit of 50 km/h, as did Victoria and NSW until the early 1960s.

We therefore recommend that:

1. The tolerance allowed in the enforcement of the 60 km/h speed limit be reduced or removed.

2. The level of enforcement of the 60 km/h speed limit be increased.

3. The penalties for speeding and illegal drink driving be reviewed to align them more closely to the risk of being involved in a casualty crash.

4. The level of public awareness of the risk of involvement in a casualty crash associated with speeding be increased with the aim of developing a culture of compliance with speed limits, similar to that which has developed in relation to compliance with blood alcohol limits during the past 15 years.

5. To assist with the preceding recommendation, we also recommend that the results of this study be widely publicised, emphasising the risks associated with speeding in relation to the risks associated with illegal drink driving.

6. After a period with stricter enforcement of the 60 km/h urban area speed limit, consideration be given to changing the urban area speed limit to 50 km/h on all roads, as in most other highly motorised countries.