Rural seagull treatments, their design and practical application. A case study

There are many variations of rural seagull treatments in NSW which differ from the standard Austroads design layout. Many seagull treatments installed vary in layout and in some cases can be confusing for motorists. As a result, their success as a road safety treatment at rural junctions has been mixed. This case study is the junction of the Princes Highway and Island Point Road on the South Coast of NSW, approximately 170 kilometres south of Sydney. The junction has gone through 3 different modifications in an attempt to reduce the number of crashes, mainly straight through impacting with right turning vehicles. While the initial design gave protection to the right turning vehicles from rear end crashes, it did not arrest a growing trend in other crash types. A second design modification was then constructed in accordance with the standard layout. Unfortunately, the second design had little effect on the straight through impacting with right turning vehicle crashes. Further crash analysis was undertaken but at a much higher level which uncovered a behavioural issue that had not previously been evident. As a result of the analysis a third design modification was implemented. This latest modification, which has now been in operation for over 3 years, coincided with a significant decrease in the number of crashes at this junction, especially straight through impacting with right turning vehicles. This paper explores the various design modifications, the detailed crash analysis and the final design option which saw the significant reduction of crashes.