On 1 March 2003 the default urban speed limit in South Australia was reduced from 60 kilometres per hour to 50 kilometres per hour. On-road speeds just before the default limit was introduced were compared with speeds a year later. The numbers of casualty crashes and casualties in the year before the default limit was introduced were compared with the corresponding numbers in the first year that the default limit was in effect. On roads where the speed limit was reduced from 60 kilometres per hour to 50 kilometres per hour, average vehicle speeds decreased by 2.3 kilometres per hour and casualties by 24 per cent. On roads where the speed limit remained at 60 kilometres per hour, average vehicle speeds decreased by 0.9 kilometres per hour and casualties by 7 per cent. (Author/publisher)
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