Author(s):
J.D. Miles, B.M. Kotwal, S.E. Hammond, F. Ye
Publication Date
April 2014
Abstract
Researchers at Texas A&M Transportation Institute completed a study of E-Modified, Enhanced E-Modified, and Clearview 5W for overhead and shoulder-mounted guide signs. The overhead guide signs consisted of three six-letter word stacked over each other at a standard spacing. The test word was on the middle line and had a 16-inch tall leading uppercase letter followed by a combination of lowercase ascender and neutral letters, lowercase descender and neutral letters, or all lowercase neutral letters, of varying loop heights depending on letter style. The shoulder-mounted signs consisted of single two-digit numbers. Both the word and number legends were chosen to have similar footprints to minimize the likelihood of guessing based on recognition rather than legibility. Legibility distance data were recorded for each word read; however, the researchers completed the analysis based on the legibility index (LI), which is the legibility distance divided by the legend height. Clearview 5W and Enhanced E-Modified were not statistically different than E-Modified. The only statistically significant differences reported were with respect to subject age (e.g., 18-35, and 65+) and day versus night, and at night within Clearview 5W with respect to legend type. The mean LI were 68.9 and 45.2 for 18-35 versus 65+ participants in the daytime condition, respectively, and 50.2 and 36.4 fir 18-35 versus 65+ participants in the nighttime condition, respectively. It was shown that the cost to implement Clearview 5W would be more expensive than E-Modified based on the cost of the license and the increased size of the signs versus E-Modified. Based on these findings, the researchers do not recommended using Clearview 5W. With drivers 65 years of age and older achieving nearly 81 percent of daytime legibility, it is questionable how much further improvement can be achieved. so it is recommended that only fonts or policies that reduce the costs of signs without reducing the safety be investigated in future studies. If further font evaluations are to be conducted that focus halation, the researchers recommend focusing on shoulder-mounted signs that have luminance values than overhead signs.
Report Number:
99007
Keywords:
Ascender, Clearview 5W, Daytime, Descender, E-Modified, Enhanced E-Modified, Guide Sign, Legibility, Neutral, Nighttime, Numbers, Overhead, Shoulder
Link(s):
Document/Product
http://tti.tamu.edu/documents/TTI-2014-3.pdf
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