A design of experimental approach to study the road marking luminance contrast and variable message signs
Manuscript I presents a study on the effects of road marking luminance contrast on driving safety through laboratory driving simulation experiments. Presented with a series of video stimuli showing different levels of marking luminance contrasts, subjects made responses based on their comprehension of marking color and configuration. It was found that subjects' responses dropped with the increment of marking luminance contrast. White markings are more visible than yellow markings. Driving at higher speeds got faster responses. Older subjects took the longest responses while younger subjects took the least. Female subjects responded slower than males. To warrant proper responses and assure safe driving, the minimum contrast values for white and yellow road markings are estimated to be 1.1 and 3.3∼3.5 respectively. ^ Manuscript II describes a study on the font color and size in variable message signs (VMSs) through laboratory driving simulation experiments. Computer generated VMS images, merged with a driver's view driving video, were projected onto a screen in front of the test vehicle. A subject in the driver's seat was required to make responses signaling her/his comprehension of the VMS stimuli. Eighteen subjects balanced by age and gender participated the experiments. It was found that font color, drivers' age and gender significantly affected subjects' responses. Green and 5 x 7 dot matrix are the best font color and size respectively. Older drivers responded the fastest but with the lowest accuracy. No significant correlations were found between subjects' responses and accuracy. Different subjects' responses were significantly different. The effects of font color and size were consistent among different subjects. ^ Manuscript III presents the study of display format, number of message lines, driving lane, and their interactions by using the same experiment setup as that in manuscript II. It was found that discretely displayed messages took less responses than sequentially displayed ones. Single-line messages were better than multiple-line ones. Motorists could better view VMSs when driving in the outer lane. Older drivers exhibited slower response and less accuracy than younger drivers; females exhibited slower response but higher accuracy than males. ^
"A design of experimental approach to study the road marking luminance contrast and variable message signs"
Dissertations and Master's Theses (Campus Access).