A sign becomes inclusive when its message can survive more than one way of receiving it.

A message that works only one way leaves out everyone who receives differently. Words alone exclude someone who cannot read them quickly, a symbol alone excludes someone who does not know it, colour alone excludes anybody who does not see the difference. Saying the same thing in a second form is what makes it dependable. Repetition here is reach rather than clutter.

Look at a sign or notice you are responsible for and ask how someone would get the message without the part you relied on. Add the second channel, whether that is plain words, a picture or a shape. Design that works twice works for more people.