This study investigates whether the application of orientation indication enables a driver to obtain a reliable impression of the course of an unlit highway over a distance of circa 1000 meter. Model computations and experiments showed that it is not possible to attain the required visibility range using reflectors. As a result, orientation indication for unlit highways should consist of small light sources. Using computer generated images, the orientation indication was tested: (1) for 2 values of the height of the indicators (8 meter and 16 meter); and (2) for 2 values of the distance between the indicators (75 meter and 150 meter). The detection distance was chosen as a quality measure of the orientation indication. The detection distance was defined as the mean distance from the onset of the deviation of the straight course from which this deviation was perceived correctly and consistently in 80% of all presentations. It was tested for 4 different bends and 1 slope which of the 4 orientation indication configurations yields the largest detection distance. The experimental results indicate that the orientation indication with the indicators in the highest position (16 meter) and with the smallest distance between the indicators (75 meter) yielded large detection distances for all roads studied.
Abstract