Regarding color blindness, you can also print the name of the color on the ticket. Or increase contrast: "What can be done to avoid confusion? Most sources on

Regarding color blindness, you can also print the name of the color on the ticket. Or increase contrast: "What can be done to avoid confusion? Most sources on usability and interface design suggest avoid relying on color coding exclusively. Always provide an additional cue; don't rely on color alone. For example, the standard default web browser of a link is underlined blue lettering. Interestingly, this particular color coding would stand up quite well, even without the additional cue of the underline, since blue is the universally recognizable color. A second way to counteract color deficiency confusions is to make sure that colors have a high degree of contrast with each other." http://www.stcsig.org/usability/newsletter/9910-color-blindness.html http://www.stcsig.org/usability/newsletter/9910-color-blindn... There are a lot of guidelines and protocols for managing user color blindness in interfaces... it's generally not a sufficient reason to completely avoid the use of color in all cases.