This study investigated how many lines of text on a temporary information road sign could be correctly read in 720 ms - the time calculated that a driver with 6/12 visual acuity travelling at 60 km/h has to read the sign. Six signs representing yellow-and-black temporary information road signs having 1-5 lines of text were presented to 25 subjects in a Sydney optometry practice. Each sign was displayed for 720 ms and the subject was required to report what they read on each sign. Based on a criterion of 95 percent correct recognition, the results suggest that drivers can read the message on a temporary information road sign only if the sign displays either one line of text, or 2-3 lines of text if the first line contains the primary message. These results indicate that many temporary information road signs currently in use on Australian roads are not able to be read by the majority of drivers, and therefore do not fulfil the purpose for which they were designed. (a).
Abstract