National Academies’ Nighttime Overhead Signage Luminance Levels

The National Academies Press issued an 80-page report, in May 2017, entitled “Guidelines for Nighttime Overhead Sign Visibility.” It includes a chart headlined “Luminance Levels for Overhead Signs.” It lists five different visual complexity levels, ranging from a dark rural area to a commercial downtown district. It then suggests minimum luminance levels in terms of candelas per square foot and […]

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Texas/Pennsylvania DOT Studies Says Clearview Font Improves Sign Legibility

A study conducted jointly by the Texas and Pennsylvania Departments of Transportation in April 2006 concluded the Clearview font increased the visibility distance for drives by 12% versus the existing Series E Modified font. In 1994, the Federal Highway Administration determined highway signs were no longer visible enough for a population that included older drivers. Over the next […]

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Penn State Study Examines Font Legibility

The Larson Transportation Institute at Penn State University conducted a study on font legibility through a grant from Gemini Inc. (Cannon Falls, MN), a manufacturer of dimensional letters. The following is the Executive Summary from the report. For information about the full report, contact Philip Garvey at pmg4@psu.edu. Background and objectives The enormous font selection […]

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What the Street Graphics Books Say About Signs

In 1971, the American Planning Association (APA) began distributing a book called Street Graphics and the Law, which was authored by Daniel Mandelker and William Ewald. It recommended the uncompensated taking of signs and governmental control of signs’ design, message and content. The authors stated that their conclusions were substantially based on 1956 research conducted […]

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What are Some Guidelines for Electronic Message Center Resolution?

A critical aspect of any sign is viewing distance. The appropriate amount of detail varies greatly, depending on the distance from which the sign will be viewed. In digital printing, this “resolution” is determined by “dots per inch,” or DPI. The more closely an image will be viewed, the higher its resolution needs to be, […]

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How Big Do the Letters on Signs, Parallel to the Road, Need to Be?

As noted elsewhere on this website, “visual acuity” and “conspicuity” and “cone of vision” are very important for signs, because motorists must be able to detect signs, read them and then react to them in a few seconds. So how much does the visibility change when a sign directly faces the driver (perpendicular to the […]

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What Does “Conspicuity” Mean for Signage?

Conspicuity for signage is determined by the contrast between the sign and its background. A sign must be conspicuous first, because, without it, the sign’s legibility and readability are moot points. While the appropriate size for signs is addressed on this website under the heading “How big should a sign’s letters be?”, conspicuity includes factors […]

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How Big Should a Sign’s Letters Be?

Signs need to be legible and readable, for both pedestrians and motorists. But the safety consideration becomes paramount for the latter. Consequently, the Federal Highway Administration (FHWA) sets minimum standards for the letters that appear on the interstate signs that say “Cincinnati” and “Second St.” and “Next Exit.” These standards are outlined in the FHWA-produced […]

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