Effects of Traffic Control Devices and Road Scenes on a Driver's Judgment of Curve Sharpness

Abstract

The effects of traffic control devices and road scene on a driver's judgment of curve sharpness were investigated by field experiments on a 15-km section of rural highway running through a hilly area in Hokkaido. The configurations of traffic control devices at 65 curves were obtained from the road maintenance database. The favorability of the road scene was determined subjectively. Each of the 6 subjects drove a vehicle installed with instruments. The subject estimated the sharpness of the target curve before that curve and assessed the accuracy of that judgment subjectively after the target curve. Cluster analysis detected goupings of the 65 curves in terms of driver assessment of sharpness. Thdraffic control devices likechevron sign and the curve radius had a strong positive effect in daytime and at night on judgment of the target curve. In addition, there were some dangerous curves where the subjects underestimated the sharpness before entering the curve. Traffic control devices to inform of curve depth should be installed to increase the accuracy of sharpness judgment