Such images are often used in airports, train stations, hotels, and other public places for foreign tourists, as well as being easier to identify than strings of text.
[1][2] As works of the United States government, the images are in the public domain and thus can be used by anyone for any purpose, without licensing issues.
In the 1970s, the United States Department of Transportation recognized the shortcomings of pictograms drawn on an ad hoc basis at transportation-related facilities across the United States and commissioned the American Institute of Graphic Arts to produce a comprehensive set of pictograms.
The designers rated these pictograms based on criteria such as their legibility, their international recognizability and their resistance to vandalism.
After determining which features were the most successful and appropriate, the designers drew a set of pictograms to represent 34 meanings requested by the DOT.
A key goal was to avoid starting from scratch when possible, and instead build off previous development of robust symbol designs in existing systems.
The Department of Transportation's Office of Facilitation and AIGA committee devised the initial list of 34 messages.
These messages were broken into four broad categories: 'Public Services', facility services and modes of transport (Telephones, toilets, first aid); 'Concessions', commercial activities (Car rental, coffee shop, shops); 'Processing Activities', passenger related processes (Ticket purchase, customs); 'Regulations', (No smoking, No entry).
Is the construction of this symbol consistent in its use of figure/ground, solid/outline, overlapping, transparency, orientation, format, scale, color and texture?
Can this symbol be enlarged and reduced successfully?Scores for these three categories were awarded by each committee member on a scale of 1 (weak) to 5 (strong).
The guidelines present guidance to a design team, rather than a strict set of requirements for typeface, sizes, colors, illumination, etc, that must be adhered to.
This decision is intended to strike a balance between creating a perfect system while allowing symbols to appropriately integrate into the environment they're being used in.
[2] Letter size should be decided on a situational basis, using testing, however a general rule is that 1 inch (25 mm) in height for ever 50 feet (15 m) of viewing distance.
For example, in 1999 the Red Cross informed Ultimate Symbol that their 1996 publication Official Signs & Icons, featuring various symbol collections, that the Red Cross in the AIGA pictogram collection was a violation of the Geneva Convention and United States trademark laws, and asked for its removal from future editions.