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HFG CHANGEABLE MESSAGE SIGNS Version 1.0 PRESENTATION OF BILINGUAL INFORMATION Introduction Bilingual information refers to information that is presented in more than one language on CMSs. Drivers spend 10% to 15% more time reading bilingual than monolingual signs if they have more than 1 line in each language (1). However, in areas with large culturally diverse populations or areas with heavy international tourism, signs that present messages in more than one language may be required. Presenting bilingual information on a sign can increase reading times for monolingual and bilingual drivers. It is important to minimize this increase in reading times to reduce driver distraction. Design Guidelines Guideline Example (adapted from Jamson (1)) Group lines by language rather than content Display the most widely spoken language first Distinguish between languages on signs with two or more lines of text per language by using: Case: display one language in all uppercase and the other in initial case (first letters of words capitalized) Color: display one language in one color and the other in a different color Spacing: leave a row blank between message lines in different languages Based Primarily on Based Equally on Expert Judgment Based Primarily on Expert Judgment and Empirical Data Empirical Data 19-14

OCR for page 49
HFG CHANGEABLE MESSAGE SIGNS Version 1.0 Discussion Reading response time for one line of relevant text on a two-line bilingual sign is not significantly different than reading response time for a one-line monolingual sign (1). Also, none of the demarcation techniques for the different languages made an impact on reading times for two-line bilingual signs. However, reading response times for two lines of relevant text on a four-line bilingual sign are significantly longer than reading response times for a two-line monolingual sign. The time required to read two lines of relevant text on a four-line bilingual sign is comparable to the time required to read four lines on a monolingual sign. Thus, introducing two lines of a second language strongly impacts reading performance. This impact can be mitigated through any of the demarcation techniques of color, case, or spacing. Learning and expectancy effects were tested for case, color, and language order (1). Case showed neither effect, suggesting that drivers did not notice that it was being used to distinguish between languages. Color showed only expectancy, meaning that reading times did not decrease as more signs were viewed with the same color pattern, but times significantly increased when that pattern reversed. Language order showed both effects, showing that drivers learned the pattern and then were confused when it changed. These results speak to the effectiveness of different demarcation methods as well as the importance of consistency across bilingual message signs in an area. Reading time is minimized when the dominant language of the driver is positioned first on the sign, for signs containing either one or two lines of relevant text per language (1). This finding has also been verified for static signs in both English/Welsh and English/French. The effect is greater for m onolingual readers, based on bilingual readers in the English/French study seeming to respond to whichever language was first on the sign. The studies that are cited on bilingual messages were performed using English and Welsh, which have identical character sets. Identical character sets lead drivers and study participants to attempt to read both sets of messages before finding one illegible (2). Results may not hold for bilingual signs displaying languages that use more distinctive character sets. Additionally, most of the guidance provided above is based upon a single, computer- based study. Design Issues Multiple methods were suggested by Jamson (1) for distinguishing between messages in different languages. Although the methods were proven to provide benefits for drivers, care should be used when applying some of these techniques. When the languages are distinguished by color, the colors selected should have neutral or equal meaning to drivers (1). For example, red can imply urgency, causing drivers to perceive the message in one language as more urgent. The colors should also have equal luminance in changing light and weather conditions. Language differentiation by case has disadvantages as well. Some studies indicate that mixed font is easier to read, while words written in all capital letters could be seen as higher priority. Also, displaying lowercase letters requires more space on the CMS to accommodate the descenders. Providing a blank row between languages has been shown to improve glance legibility (1). The greatest benefit was provided to monolingual drivers, especially when their language was not dominant. Multiple methods can be used concurrently to distinguish between languages; however, these effects were not studied. An additional issue is the splitting of bilingual messages into multiple phases. The phase guidelines from Determining Appropriate Message Length (page 19-6) should be taken into consideration. Jamson (1) found that if a four-line bilingual message is split into two phases in such a way that each phase contains one line in each language that does not make sense alone, reading times for both phases increase significantly. The concern with presenting the entire message in one language and then another language (each phase is monolingual) is that drivers may encounter the sign when it is not displaying a language that they understand while other drivers, who could comprehend the message, may already be reacting in ways that are unexpected (1). Cross References Determining Appropriate Message Length, 19-6 Key References 1. Jamson, S.L. (2004). Evaluation of techniques to improve the legibility of bilingual variable message signs. Advances in Transportation Studies: An International Journal, Section B, 4, 71-88. 2. Jamson, S.L., Tate, F.N., and Jamson, A.H. (2001). Bilingual variable message signs: a study of information presentation and driver distraction. Driving Assessment 2001: The First International Driving Symposium on Human Factors in Driver Assessment, Training and Vehicle Design, 153-158. 19-15