Readability evaluation and improvement of the display of variable road information boards with two-events messages

Abstract

In recent years, variable road information boards on expressways have become highly developed. However, due to differences in times of posting and renewal, these information boards are not uniform in graphical symbol designs and display methods of character information. Particularly, it has been pointed out that some graphical symbols among the present ones are not understood correctly by road users. In previous studies, graphical symbols were newly created and readability of 2-event information boards with symbols was reviewed. In this study, upon analyzing these previous study results, we tried to clarify issues of the display method in 2-event information boards. Furthermore, on the basis of these issues, we developed new display designs for information boards and verified the efficacy by evaluating their readability. As a result, it has been suggested that the intelligibility of the second event, which is a highly important issue, improves substantially by laying out two 1-event information boards alongside the other.