If speed limits were appropriate, we wouldn’t mind so much

As it stands, both the behaviour and attitudes of drivers indicate the bureaucrats are getting it wrong. Many roads, particularly those with speed limits of 80 km/hr or higher, would have higher limits if they were determined by drivers. Are the bureaucrats smarter or wiser than their fellow citizens, or do they just believe they know better? Are we so inept at making judgements about our own safety that we need public servants to do it for us?

There is an internationally recognised method for setting speed limits based on public opinion, known as the 85^th percentile formula. In essence it involves the temporary removal of speed limits while speeds are monitored. At the conclusion of the period a limit is reimposed at or slightly above the speed at which 85 per cent of drivers travel.

The method is based on the assumption that the large majority of drivers are reasonable and prudent, do not want to crash, and wish to reach their destination in the shortest possible time.

It is supported by evidence showing that those who exceed speed limits based on the 85^th percentile are substantially more likely to cause accidents (as are those who travel below the 15^th percentile). Enforcement directed at those drivers thus has a positive impact on road safety while enjoying a high level of driver support.

The 85^th percentile formula is applied in parts of the U.S. but, despite being well understood by our road safety lobby, has never been applied in Australia.

The result is enormous cynicism about the enforcement of speed limits and its contribution to government revenue. There is significant misallocation of resources directed at catching drivers who breach limits for which they have no respect, wasting taxpayers’ funds and bringing the law and police into contempt.

None of this is necessary. If the 85^th percentile formula was used to set speed limits, they would have demonstrable acceptance. Rather than being despised, traffic police would be respected. Speed cameras and other enforcement methods (but perhaps not in-car monitoring) would be accepted far more readily. If there was public concern about increases in road deaths and injuries, this could be expressed through periodic retesting of the 85^th percentile.

Governments should stop treating motorists like naughty children and a source of additional revenue. If the government serves the people rather than vice versa, speed limits should have the approval of most drivers.