Visibility under night driving conditions

Abstract

The visibilities of a pedestrian dummy and disc objects of varying size and contrast were measured under dynamic night driving conditions on an unlit open road and in a road lighting situation for which the average pavement luminance was 0. 8 cd/m². The visibilities of the objects could largely be described by a standard luminous increment-visual area characteristic. Under road lighting conditions, negative contrasts (silhouette vision) were found to give slightly greater visibilities than positive contrasts. It was found that a contrast multiplier of 4 was required in applying laboratory 50% probability of detection thresholds to a 'just visible' criterion level of visibility in the field experiments, though in practical conditions contrast multipliers as large as 30 may be required.