Trends in driver speed behaviours on Perth metropolitan road network 2000 to 2014

Eleven annual speed surveys were conducted in the Perth metropolitan area during the period between March and August in 2000, 2003, 2004, 2005, 2007, 2008, 2010, 2011, 2012, 2013 and 2014 inclusive, to measure driver speed compliance across the network of speed limit roads ranging from 60 km/h to 100 km/h. Since 2005 the surveys have been expanded with samples of sites on the 50 km/h road network. The 2000 survey was used as the baseline year for the comparisons with all subsequent surveys from which road safety and speed performance indicators were derived as measures of driver speed behaviours over the time. The principal objective of the surveys was to measure changes in driver speed behaviours at general locations of the road network over time and to relate those changes to the effectiveness of various speed related road safety programs implemented in the state. Effectiveness of speed road safety programmes is estimated in terms of changes in: speed compliance rates, proportion of drivers exceeding 10 or more km/h above the speed limit, 85th percentile and mean speed. The study found that under free-flowing condition over the metropolitan network of all speed limits (excluding 50 km/h and 110 km/h roads) in 2000, 53% of all vehicles travelled at or below posted speed limits. The results from the analysis of the data collected in the speed surveys from 2000 to 2014 suggested that speed enforcement strategies should incorporate consideration of the differences in driver speed behaviours associated with road type, speed limit and temporal factors such as day of the week and time of day.