This report describes the fourth and final stage of a comprehensive research program to demonstrate the on-road travel speed, braking and lateral placement effects of two perceptual countermeasures. The first involved an enhanced curvature treatment comprising variable height posts and increased curvature spacing. The second involved a peripheral edgeline “Herringbone” treatment in the approach to an intersection. Treatments were applied to sites in Victoria and New South Wales where similar control sites were available. Data were collected before installation, immediately after and 12 months after installation and comprised speed measures every 20m in the approach to the curve and intersection as well as braking performance and lateral placement. An evaluation of crashes before and after treatment was not possible due to a lack of data. At curves, travel speed results were quite mixed where speed reductions and speed increases were observed immediately after and 12 months later. Braking results tended to support travel speed findings and some improvements in lateral placement were also observed at these locations. At intersections, the results were more stable where speed reductions were more common both immediately after treatment as well as longer-term. There were no differences in braking and lateral placement at these straight-road locations. The findings seem to have been unduly influenced to some degree by misadventure and wear and tear at these sites. It is argued that while the effectiveness of these treatments may be site specific to some degree, they do offer a low-cost solution to reducing travel speed at hazardous locations. Recommendations are made for further research in this area. (Author/publisher)
Abstract