49 CFR Parts 37 & 38 - Department of Transportation (DOT) ADA Regulations

IV. Priority Seating Signs and Other Signage

A. Finish and Contrast. The characters and background of signs should be eggshell, matte, or other non-glare finish. An eggshell finish (11 to 19 degree gloss on 60 degree glossimeter) is recommended. Characters and symbols shall contrast with their background—either light characters on a dark background or dark characters on a light background. Research indicates that signs are more legible for persons with low vision when characters contrast with their background by at least 70 percent. Contrast in percent shall be determined by:

Contrast=[B−B)/B] × 100

Where B = light reflectance value (LRV) of the lighter area

and B = light reflectance value (LRV) of the darker area.

Note that in any application both white and black are never absolute; thus, B never equals 100 and B is always greater than 0.

The greatest readability is usually achieved through the use of light-colored characters or symbols on a dark background.

B. Destination and Route Signs. (The following specifications, which are required for buses (§38.39), are recommended for other types of vehicles, particularly light rail vehicles, were appropriate.)

1. Where destination or route information is displayed on the exterior of a vehicle, each vehicle shall have illuminated signs on the front and boarding side of the vehicle.

2. Characters on signs required by paragraph IV.B.1 of this appendix shall have a width-to-height ratio between 3:5 and 1:1 and a stroke width-to-height ratio between 1:5 and 1:10, with a minimum character height (using an upper case “X”) of 1 inch for signs on the boarding side and a minimum character height of 2 inches for front “headsigns,” with “wide” spacing (generally, the space between letters shall be 1/16 the height of upper case letters), and shall contrast with the background, either dark-on-light or light-on-dark, or as recommended above.

C. Designation of Accessible Vehicles. The International Symbol of Accessibility should be displayed as shown in Figure 6.