Morse code? Morse code uses dots and dashes. You can use it as a sign language to communicate (thats what some WWII POWs did in Japanese concentration camps) and its mostly spoken (or heard) in blips and bloops (more or less) and sometimes seen a little.
It follows street sign format, and "blind drive" is a common street sign (at least around me); the dot could represent Braille (used by the blind), and the line could indicate forward movement (=drive?).