Flashing Message Features on Changeable Message Signs

Abstract

Studies were conducted with a driving simulator to determine the effects of displaying changeable-message-sign messages with dynamic features consisting of (a) flashing all lines simultaneously in a one-phase, three-line message and (b) flashing one line (top line) of a one-phase, three-line message. In the first dynamic feature, all three lines were flashed. Only the top line was flashed for the second dynamic feature. Messages with these two dynamic features were compared with comparable static messages. No differences in average reading time were found between the messages in which all three lines flashed and static messages. However, the results suggest that flashing an entire one-phase message may have adverse effects on message understanding for drivers who are unfamiliar with this dynamic mode of display. A significant percentage of the subjects preferred the static display. The average reading time for the flashing line (top line) messages was significantly longer than for the static messages. The results also suggest that unfamiliar drivers will be adversely affected by this particular display feature, relative to comprehension of the entire message. The subjects liked the flashing line and static messages equally well. No differences were found by age, education, and gender among the three dynamic message modes and their alternatives. In addition, no differences were noticed in driving performance.