A systematic and ongoing method of measuring vehicle speeds was introduced in South Australia in 2007 in order to assess the effects of speed reduction countermeasures and to monitor the speed behaviour of South Australian motorists over time.
This Report summarises the data collected in 2009 and through a new methodology allows direct comparisons with previous surveys and partial surveys dating back to 2002.
Low speed roads showed a marked reduction in mean speed following the introduction of the default 50 km/h speed limit in 2003 and for some years after. Mean speeds on these roads generally went up from 2005 to 2007 but down again in 2008. Mean speeds on these roads appear not to have changed between 2008 and 2009.
The speeds of vehicles on high speed rural roads have remained relatively unchanged between 2006 and 2009 with the exception of a significant drop in the speeds of vehicles on 100 km/h roads between 2007 and 2008. It is not clear what the reasons for the observed speed changes are although a lower police enforcement tolerance and a large advertising campaign may have played some role in the speed changes between 2007 and 2008.