Rethinking ADA signage standards for low-vision accessibility

Abstract

Americans With Disabilities Act (ADA) and International Code Council (ICC) standards for accessible buildings and facilities affect design and construction of all new and renovated buildings throughout the United States, and form the basis for compliance with the ADA. While these standards may result in acceptable accessibility for people who are fully blind, they fall far short of what they could and should accomplish for those with low vision. In this article I critique the standards, detailing their lack of evidence base and other shortcomings. I suggest that simply making existing requirements stricter (e.g., by mandating larger letter size or higher contrasts) will not ensure visual accessibility and therefore cannot act as a valid basis for compliance with the law. I propose two remedies. First, requirements for visual characteristics of signs intended to improve access for those with low vision should be expressed not in terms of physical features, such as character height and contrast, but rather in terms of the distance at which a sign can be read by someone with nominally normal (20/20) visual acuity under expected lighting conditions for the installed environment. This would give sign designers greater choice in design parameters but place on them the burden of ensuring legibility. Second, mounting of directional signs, which are critical for effective and efficient wayfinding, should be required to be in consistent and approachable locations so that those with reduced acuity may view them at close distance.

Figure 1

Examples of a designation sign (left) and a directional and informational sign (right).

Figure 2

(a) Minimally compliant (when printed so that x-height is 0.4 in.) visual-only sign set in a sans serif font (Gill Sans). (b) Minimally compliant raised visual sign set in the same font, for comparison. Obviously (b) will be readable at greater distance or with significantly less magnification than (a).

Figure 3

A traveler with average eye height viewing a sign whose characters are 40 in. from the finished floor, where an obstruction restricts horizontal approach to the sign. In this situation, character height must meet minimums in linear size as shown in Table 2, but not in visual angle (α).

Figure 4

A compliant visual-only designation sign under the standards at actual size (when printed so that the x-height is 0.35 in.). The text is set in Cochin (Linotype AG) at 68.4 points. The x-height in this font is 57% of the I-height and 37% of the nominal point size.

Figure 5

The text in this sign is compliant with the standards, since there is a measurable difference in lightness between characters and background.

Figure 6

Optimal and approachable wall sign placement (shown in green) for visually impaired travelers entering the three main types of corridor intersections along the wall to their right. These accessible signs should supplement signs designed for able-sighted travelers, such as the overhead signs indicated.