Objective. There are about 1.6 millions visually disabled persons in Japan. It is well known that about 90% of those are the low vision and the rest is the blind. Some of the low vision can walk independently by confirming position of marks or obstacles placed on road surface. However, it is considered that use of un appropriate parameters such as material, luminance contrast, illumination in road surface may affect visibility for the low vision. Therefore, the low vision sometimes miss-recognize road surfaces as holes or ditches. The purpose of our research is to find parameters of road surface that causes this kind of miss-recognition. As the preliminary result of our research, this paper describes how the low vision recognizes road surface incorrectly.

Main content. Visibility of road surfaces' lines that have different parameters in width, luminance contrast, and illumination was experimentally studied. Firstly, it was studied how the low vision recognized each line on road surface. In this experiment, one of the lines was randomly showed to each subject respectively. Secondly, eight lines that have different parameters respectively were showed to a subject at a time. The lines were arranged in ascending order. At the end of each experiment, comments from a subject were obtained. Fifty-nine low vision persons were participated as subjects in these experiments.

Results. Three results were provided from these experiments. It was observed at first that miss-recognition of lines on road surfaces occurred more frequently according to increment of luminance contrast. Secondly, there were no relations between width and visibility of the lines. Finally, there were no relations between illumination and visibility of the lines. In addition to those, it was indicated from comments of subjects that extremely low illumination forced subjects not to walk without fear.

Conclusion. The elderly have been increasing rapidly in these decades. Furthermore, majority of the elderly are low vision. Independent walking is the primary requirement for them to have good quality of life. In the next step of our research, it would be necessary to focus not only on the low vision but also on the elderly.