Vehicle speeds in South Australia 2008

Abstract

A systematic and ongoing method of measuring vehicle speeds was introduced in South Australia in 2007 to assess the effects of speed reduction countermeasures and to monitor the speed behaviour of South Australian motorists over time. Speed data was collected for one week at each of 130 sites in 2007 and 2008. Summary volume and speed statistics and speed distributions are given for each of the road types surveyed in both years (for all vehicles and just free speed vehicles). Changes in speed measurements for each of the road types between 2007 and 2008 were tested for statistical significance. All road types showed reductions in speed measurements from 2007 to 2008 with the exception of 80 km/h Adelaide arterial roads. The average reduction in mean speed across all roads surveyed was 0.76 km/h. Limited historical surveys on a set of roads in built up areas indicated that travelling speeds on those roads fell in 2003 (after the introduction of the default 50 km/h speed limit in March 2003) compared to 2002 and fell again in 2005. However, travelling speeds on those roads increased in 2007 compared to 2005 before falling again in 2008. Analysis of previously collected data for a limited subset of rural roads indicated a similar pattern with speeds generally rising from 2006 to 2007 before falling in 2008.