STUDY LEGIBILITY OF ROAD SIGN TYPOGRAPHY AND FORMAT
Record Type: RiP
The current guide sign alphabet is incompatible with recent improvements in signing material and changes in driver characteristics. The thick stroke design of the Series E(M) highway alphabet, both upper and lower case, when used with newly-developed, high-brightness signing materials results in a phenomenon known as irradiation or halation. Irradiation has become a problem because the reflective letter material is now so bright that it bleeds into the letter form's open spaces, creating a blobbing effect that reduces legibility. This irradiation effect is particularly troubling for older drivers. To reduce the effects of this phenomenon, a new highway font was developed. The basic principle behind the design of the new font, which has been named Clearview, was the opening of the interior spaces of the letter forms to allow irradiation to occur without diminishing the distance at which the alphabet could be read. As a result of field research conducted at the Pennsylvania State University's Pennsylvania Transportation Institute using older travelers and high-brightness materials, nighttime legibility distances for the Clearview font are 16% greater than Standard Highway Series E(M). With 15-inch letter height, this could increase legibility distance by 150 ft., allowing drivers almost two seconds longer to read highway guide signs.
Status: Active
TRB Accession Number: 792675
Total Dollars: 0
Source Organization: Pennsylvania State University, University Park
Date Added: 07/10/2002
Index Terms: Roadside structures, Signs, Legibility, Guide signs, Formatting, Lettering, Research projects,
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