Abstract: A three-dimensional road sign portraying the International "DO NOT ENTER" symbol for warning traffic approaching a one way side street from either side of the street. The International "DO NOT ENTER" sign uses vertically separated red and white zones which retain the information content when expanded into a three-dimensional shape. The sign is painted or embossed such that when in place and approached front end on, it is virtually indistinguishable from a conventional "DO NOT ENTER" sign. When approached from either side of the sign, the vertically separated red and white zones are seen as the information that warns the approaching traffic of the one way restriction. A single sign thus warns at a greater distance and angle than the conventional sign and reduces ambiguities.