Basing his work in part on iconography for the ’64 Olympic Games, Aicher created a set of pictograms meant to provide a visual interpretation of the sport they featured so that athletes and visitors to the Olympic village and stadium could find their way around. He created pictograms using a series of grid systems and a specific bright colour palette that he chose for these Games. These designs were directly influential on the DOT pictograms, developed in 1974 by the United States Department of Transportation, which applied the same principles to standard public signage such as those for toilets and telephones; the DOT pictograms have in turn been used around the world.
http://www.historygraphicdesign.com/the-age-of-information/the-international-typographic-style/172-otl-aicher