Prior to this effort, numerous international, national and local organizations had devised symbols to guide passengers and pedestrians through transportation facilities and other sites of international exchange. While effective individual symbols had been designed, there was no system of signs that communicated the required range of complex messages, addressed people of different ages and cultures and were clearly legible at a distance.
To develop such a system, AIGA and D.O.T. compiled an inventory of symbol systems that had been used in various locations worldwide, from airports and train stations to the Olympic Games. AIGA appointed a committee of five leading designers of environmental graphics, who evaluated the symbols and made recommendations for adapting or redesigning them. Based on their conclusions, a team of AIGA member designers produced the symbols.
A first set of 34 symbols was published in 1974, and received one of the first Presidential Design Awards; 16 more symbols were added in 1979. These copyright-free symbols have become the standard for off-the-shelf symbols in the catalogues of U.S. sign companies. They are now available on the web for the first time."