Flashing Messages, Flashing Lines, and Alternating One Line on Changeable Message Signs

Abstract

Results of human factors laboratory studies conducted in Texas pertaining to the display of messages using the following dynamic characteristics of changeable message signs (CMSs) are presented: (a) the effect of flashing an entire one-frame message, (b) the effect of flashing one line of a one-frame message; and (c) the effect of alternating text on one line of a three-line CMS while keeping the other two lines of text the same. Two hundred sixty Texas drivers were recruited in Dallas, El Paso, Fort Worth, Houston, and San Antonio to participate in the laboratory studies designed to simulate these CMS characteristics on laptop computers. The drivers responded to questions designed to determine the level of recall and comprehension of the information contained in the message. Response times, message format, and sign operating preferences were also collected. The results showed that in the laboratory setting, flashing a one-frame message did not adversely affect driver recall or comprehension to a significant degree compared with when the message was not flashed. However, average reading times were significantly higher when the message was flashed. Flashing one line of a three-line message appeared to adversely affect recall of parts of the message. In addition, average reading times were significantly higher for the flashing line message. Alternating one line of text and keeping the other two lines constant did not adversely affect message recall. However, average reading times increased significantly.