DOT pictograms

Symbols were collected from a variety of sources, including railways, Olympic events, airports and government agencies to form a catalog of each type of symbol to be created for close examination. A key goal was to avoid starting from scratch when possible, and instead build off previous development of robust symbol designs in existing systems.[2]

The first overall step was to identify the symbols that were to be developed for the project, these were referred to as 'message areas'. 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).[2]

Symbols that conveyed the messages sought by the committee from the 24 sources were broken into 'concept groups', a simple grouping of symbols that used similar general designs to convey the message. For example, 'Telephone' symbols were divided into 4 concept groups: 'Telephone handset', 'Telephone dial', 'Front view of dial telephone' and 'Handset and dial'.[2]

Symbols were assessed on three characteristics: Semantic, syntactic, pragmatic.

The semantic dimension refers to the relationship of a visual image to a meaning.

How well does this symbol represent the message? Do people fail to understand the message that the symbol denotes? Do people from various cultures misunderstand this symbol? Do people of various ages fail to understand this symbol? Is it difficult to learn this symbol? Has this symbol already been widely accepted? Does this symbol contain elements that are unrelated to the message?

The syntactic dimension refers to the relationship of one visual image to another.
How does this symbol look? How well do the parts of this symbol relate to each other? How well does this symbol relate to other symbols? Is the construction of this symbol consistent in its use of figure/ground, solid/outline, overlapping, transparency, orientation, format, scale, color and texture? Does this symbol use a hierarchy of recognition? Are the most Important elements recognized first? Does this symbol seriously contradict existing standards or conventions? Is this symbol, and its elements, capable of systematic application for a variety of interrelated concepts?

The pragmatic dimension refers to the relationship of a visual image to a user.
Can a person see the sign? Is this symbol seriously affected by poor lighting conditions, oblique viewing angles, and other visual 'noise'? Does this symbol' remain visible throughout the range of typical viewing distances? Is this symbol especially vulnerable to vandalism? Is this symbol difficult to reproduce?

Can this symbol be enlarged and reduced successfully?

— Symbol Signs (1974)[2]

Scores for these three categories were awarded by each committee member on a scale of 1 (weak) to 5 (strong). In addition to the individual score of each symbol, 'concept groups' were given an overall score based on how well the concept met the three categories.[2]

Finally they made recommendations and observations based on their scores and discussions about the symbols they reviewed. For the 'Telephone' symbol, the handset icon was common but an odd shape that could be confusable for other items, like wrenches; while symbols with dials were easy to understand but already obsolete with the increased use of the push-button telephone.[2]

The recommendations were summarized to suggest the final course of action to be taken with designing a symbol for the concept. For "Telephone", the decision was made to "Modify Group 1 concept; experiment with front view of modern telephone."[lower-alpha 3][2]

The original set of symbols developed consisted of 34 symbols, primarily intended for transportation facilities. First Aid, No Smoking, No Parking and No Entry used "Ostwald number 6 1/2 pa" for the color red.[lower-alpha 7]

• Public Services
• 
  Telephone
• 
  Mail
• 
  Currency Exchange
• 
  First Aid
• 
  Lost and Found
• 
  Baggage Lockers
• 
  Elevator
• 
  Toilets, Men
• 
  Toilets, Women
• 
  Toilets
• 
  Information
• 
  Hotel Information
• 
  Taxi
• 
  Bus
• 
  Ground Transportation
• 
  Rail Transportation
• 
  Air Transportation
• 
  Heliport
• 
  Water Transportation

• Concessions
• 
  Car Rental
• 
  Restaurant
• 
  Coffee Shop
• 
  Bar
• 
  Shops

• Processing Activities
• 
  Ticket Purchase
• 
  Baggage Check-in / Baggage Claim
• 
  Customs
• 
  Immigration

• Regulations
• 
  No Smoking
• 
  Smoking
• 
  No Parking
• 
  Parking
• 
  No Entry

In 1979, the Department of Transportation requested 16 additional symbols, to fill in gaps observed in the original set. First Aid, No Smoking, No Parking, No Dogs, and No Entry used Pantone Red 032 C and Exit used Pantone Green 340 C.[3]

• Public Services
• 
  Cashier
• 
  Coat Check
• 
  Escalator
• 
  Escalator, Up
• 
  Escalator, Down
• 
  Stairs
• 
  Nursery
• 
  Drinking Fountain
• 
  Waiting Room

• Concessions
• 
  Barber Shop/Beauty Salon
• 
  Barber Shop
• 
  Beauty Salon

• Processing Activities
• 
  Departing Flights
• 
  Arriving Flights

• Regulations
• 
  No Dogs
• 
  Exit
• 
  Fire Extinguisher
• 
  Litter Disposal

An unofficial change has been forced to the original symbols following increased efforts by the American Red Cross to discourage and eliminate usage of the 'red cross' symbol as a generic symbol of first aid or medical services. 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. In 2005, the second edition of Official Signs & Icons, the red Greek cross was replaced with an identical Greek cross colored 'Safety Green' from ANSI Z535.1–2002.[4] The adoption of a green Greek cross or white Greek cross on a green background is a common replacement, due to the visual similarity and wide usage, as the white cross on green background is used in ISO 7010 to represent first aid.

• 
  First Aid[lower-alpha 8]