Analysis of treatments on the Duke's Highway in South Australia

Abstract

Since 2001 there have been a number of treatment programs applied to the Duke’s Highway in South Australia with the aim of improving the safety of the road. Between 2001-2017 the shoulders of the road have been sealed, overtaking lanes have been installed and audio tactile line marking has been installed. Since 2009, rest areas have been installed, more overtaking lanes have been installed, clear zones have been made and roadside hazards have been removed or protected. Starting in 2011, a wide centre line is being painted along the length of the road. Since 2013, the road has been resurfaced, intersections have been treated and signage has been added. Average speed cameras were installed in 2013 and activated in 2014. Taken as a group, these treatments would be expected to reduce the number of injury crashes on the Duke’s Highway beyond any pre-existing or general trend. Between 1983 and 2016 there were 742 injury crashes recorded on the Duke’s Highway in 100 and 110 km/h speed zones. Over that time period the number of injury crashes per year has been generally declining. For the 1983-2000 period the number of injury crashes declined by about 1.7% per year. For the 2001-2016 period the number of injury crashes declined by about 6.8% per year. The trends for South Australian injury crashes on all 100 and 110 km/h roads were a 1.9% reduction for 1983-2000 and a 3.0% reduction for 2001-2016. The observed reduction on the Duke’s Highway for 2001-2016 was greater than the previous trend on that road and the general South Australian trend during the same time period. This is highly suggestive of the Duke’s Highway treatments having resulted in fewer injury crashes on that road than if no treatments had been applied.