Casualties drop with reduction to 100 km/h

29 May 2015

An investigation using 20 years of crash data has shown a 27.4 per cent drop in casualty crashes on regional roads where the speed limit was reduced from 110 km/h to 100 km/h.

The findings were released in a report today by the Centre for Automotive Safety Research (CASR) at the University of Adelaide using 10 years of crash data both before and after the speed limit changed in 2003.

In July 2003, the speed limit on 1,100 kms of rural arterial roads in South Australia was reduced from 110 km/h to 100 km/h.

Early analysis had suggested that there was a 20 per cent reduction in casualty crashes but now this is much closer to 30 per cent. Regardless of the cause of a crash, a reduction in speed significantly reduces its severity.

Less road trauma also has a beneficial economic outcome. The report estimates crash savings due to the lowered speed limits at around $67 million in the 10 years since they were introduced.

CASR Research Fellow Craig Kloeden said survey data also suggests that speeds, particularly high speeds, have continued to fall on the roads that were reduced in the 10 years since the speed limit was lowered.

“This is another in a long line of studies showing that lower speed limits do in fact lead to fewer fatalities and injuries on our roads,” Mr Kloeden said.

“Since the speed limit reduction, it is estimated that 15 lives have been saved and 230 injuries have been prevented. Even small changes in speed can have big effects on safety.”

The report is available on the at

Regional forums, which include speakers from CASR, are continuing to be held with local councils to discuss speed.

This issue is one part of the Government’s road safety survey.

The public can still contribute to the road safety discussion by taking part in a 15-minute online survey  until 5 pm Friday 29 May. The survey is located at

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