Automated vehicles and the readiness of Western Australian roads

Abstract

An assessment of various line markings at nine sites along the Great Southern Highway, approximately 155 km South-East of Perth in the Wheat-Belt region of Western Australia was performed using two vehicles equipped with lane departure warning (LDW) systems during three days of on-road trials. Crossing events were performed with each trial vehicle by initially travelling at the speed limit in the centre of the lane and then instigating a drift to the left or right. A video system with two cameras, one viewing the wheel approaching the line marking of interest and one viewing the vehicle’s dashboard, was used to record whether a warning was triggered for each crossing event. Overall, 189 crossing events were measured in the data sample. Of these, 154 (81%) gave an accurate warning, with a total of 35 (19%) warning failures. Marked centrelines had the highest warning accuracy (95%), followed by marked edge lines (90%). Unmarked road edges had the lowest accuracy rate (39%). Warning failures were attributed to the absence of a marked line; the vehicle travel speed being less than the manufacturer recommended speed for system operation; the line marking being difficult to see; and the line marking retro-reflectivity and/or the daylight brightness being low. The findings of this study show that LDW systems are capable of providing appropriate warnings in rural road environments where there are suitable line markings. It was clear that the line markings being utilised on WA roads, where they have been well maintained to provide sufficient levels of contrast with the road surface and retroreflectivity, comfortably meet this level of suitability. Quantifying the exact levels of line marking contrast or retro-reflectivity required for the effective operation of lane departure warning systems was beyond the scope of this project.