DRIVER PREVIEW DISTANCES AT NIGHT BASED ON DRIVER EYE SCANNING RECORDINGS AS A FUNCTION OF PAVEMENT MARKING RETROREFLECTIVITIES

Pavement marking visibility models and tightly controlled pavement marking field experiments indicate that increased pavement marking retroreflectivity does in fact result in longer pavement marking visibility distances. The authors suggest that drivers should be provided with a pavement marking visibility distance long enough to allow for a preview time of 3.65 s at a given vehicle speed. This minimum required preview distance can be translated into a minimum required pavement marking retroreflectance. Questions were raised that perhaps drivers may not take advantage of brighter pavement markings (increased retroreflectance)--that is, drivers may not be looking as far ahead as possible from a pavement marking visibility point of view. This study was conducted to test whether drivers increase their longitudinal eye fixation distance when pavement marking retroreflectance is increased. Eye scanning data from six subjects were used to establish longitudinal eye fixation distributions on straight and level roads under low-beam illumination at night. In general, drivers appear to adjust their visual information acquisition behavior (longitudinal eye fixation distances and eye fixation preview times) when driving on roads with bright and highly visible pavement markings. Within the range of pavement marking retroreflectances investigated, it appears that, at least for half the drivers tested, brighter markings are indeed better and provide longer preview distances, which is desirable from an information acquisition, information processing, and safety point of view