Driver behaviour on divided arterial roads in the Adelaide metro area as gleaned from 90 million speeds recorded at 12 fixed sites over 40 months.

The three-year Media Evaluation Study in Adelaide tested how on-road speeds were affected in the short term by TV advertising against speeding. It was defined from June 1998 to May 2001, though speed data were in fact recorded continuously from March 1998 to June 2001. A prior statistical power analysis was based on successive days' mean speeds of all vehicles in one lane at several representative sites, but constituting a rather limited data set, see Table I. The power analysis presumed just two successive days' speeds would be used following each advertising event. As presented, it indicated easy sufficiency of verifying as significant a practically very worthwhile reduction in mean free speed of 0.3 km/h with an indicated power of about 98%. A reduction of 0.1 km/h could give an ambiguous result and there could possibly be no real reduction at all. The outcome of the study should resolve the argument about whether advertising road safety is effective in a pronounced (macro) way or in only a very limited (micro) way, when other factors are held constant. (Author/publisher) For the covering entry of this conference, please see ITRD abstract no. E206301.