Vehicle speeds in South Australia 2007

Abstract

A program designed to monitor the speed behaviour of motorists commenced at 132 sites in South Australia in 2007. The sites selected included sites with historical measurements supplemented by new sites to give a broad range of road types. Speed data was collected for one week at each of the sites and summary volume and speed statistics and speed distributions are given for each of the road types surveyed. 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 by a statistically significant amount at least on Adelaide local roads affected by the 50 km/h limit. Analysis of previously collected data for a limited subset of rural roads indicated no statistically significant change in vehicle speeds on those roads between 2006 to 2007 although there was a general upward trend in speeds on most road types. Various sampling issues encountered in the collection and analysis of the 2007 data are discussed.