Traffic sign design
||This article is written like a personal reflection or opinion essay rather than an encyclopedic description of the subject. (December 2007)|
||The examples and perspective in this article deal primarily with the United States and do not represent a worldwide view of the subject. (December 2010)|
Traffic sign design involves any tasks in the process of designing traffic signage. Traffic signs may provide information about the law, warn about dangerous conditions and guide roadway users. Traffic signs vary depending upon their use, using different symbols, colors and shapes for easy identification.
Types of Signs 
Regulatory signs 
Regulatory signs “give a direction that must be obeyed.” Often these signs show content or action that is either allowed or prohibited and these two modes are signified by colour (i.e. green and red), orientation (i.e. open circle and circle with diagonal line through the centre) and/or shape (i.e. square and triangle).
Warning signs 
Warning signs give a warning of that there are dangerous or unusual conditions ahead. Often these signs have a greater more conspicuous presence than a regulatory sign. These signs often do not have much text on them, as they should be internationally understood due to the nature of the message that they are conveying.
Information/directional signs 
Information signs give information about direction and distance, usually guiding drivers to destinations, facilities, services and attractions. Often these signs have names of locations with an arrow pointing towards the direction of the destination and a number giving the approximate distance.
Temporary Condition Signs 
These non-permanent temporary signs are erected to warn drivers of unexpected conditions such as road work zones, diversions, detours, lane closures and traffic control. Often these signs are portable and can also be digital variable message signs.
Interaction design and traffic signs 
When designing traffic signs it is recommended to follow the four basic steps of interaction design: Identifying needs and establishing user requirements, developing alternative designs, building interactive versions, evaluating the designs.
Identifying needs and establishing requirements 
Drivers, cyclists, pedestrians and other types of pedestrians are the users that will be interacting with traffic signs. These users are using the roadways for transportation purposes and must receive information about the roadways and their destinations as they are traveling.
Developing alternative designs 
This task is divided into two categories: conceptual design and physical design. Conceptual design will be the discussion of alternative traffic signs and ways of conveying information to the users. Physical design will be the discussion of what physical aspects (i.e. colour, shape, orientation) will be on the sign to convey the messages identified during the conceptual design.
Building interactive versions 
Evaluating designs 
This task is the testing of the prototypes and actual signs in order to determine if they convey the desired message in the desired time by the appropriate users. This will let the users know the usability of their signs.
Design Principles 
Traffic sign comprehension and understandability are higher when the signs comply with ergonomic principles. It is recommended to follow the below principles in order to increase driver comprehension and understandability.
Spatial Compatibility 
The matching between the physical symbols on a sign with the literal directions/information the sign is trying to convey. “The physical arrangement in space, relative to the position of information and directions.” 
- Application: Having a regulatory sign that informs a driver they must turn right, have an image of an arrow that curves to the right.
Conceptual compatibility 
The correct association between the physical symbols on a sign and the information the sign is trying to convey. Good conceptual compatibility means that a driver will know the meaning of a symbol without having to reflect and interpret its meaning.
- Application: Having an information sign that represents an airport, have an image of an airplane.
Physical representation 
The similarity between the information that is being represented and the actual content on a sign. Good physical representation means that a driver will experience what is shown on a sign.
- Application: Having a warning sign that means to watch for pedestrians have an image a person.
- Application: Having a regulatory sign that informs drivers of the current speed limit of the roadway be frequently placed along every road.
The extent to which any sign can be grouped into a type of sign with similar or equal shape, colour and orientation. Good standardization means that all signs of the same type have the same template of shape, colour and orientation. Ideally standardization should be across cities, regions and countries.
- Application: Having all warning signs have a diamond shaped with a black border and a yellow background.
Singular Functionality 
The representation of only a single meaning for a single sign. Good singular functionality means that a sign that gives information should not also imply a regulatory meaning or another piece of related information.
- Application: Having an information sign that signifies the beginning of a school zone should not also be meant to imply that the speed limit in this area is reduced.
The extent to which any sign can be seen. It should be visible by drivers of all age groups from an appropriate distance that will allow the driver to react to the signs contents. Visibility also means that the sign has enough contrast with the background to be conspicuous and that the contents on the sign have enough contrast with the background of the sign to be conspicuous.
- Application: Having a white regulatory sign have a black border with a black symbol and a red highlight. “Solar-powered smart street signs that light up for easy reading at night, can add to readability.” 
It has been shown that following these principles when designing traffic signs will make the signs more comprehensible. Minimizing the time and effort it takes drivers to interpret traffic signs may help to reduce driver mental workload and frustration. It is also especially important to attempt to follow the standardization principle because, due to the increase in globalization, many drivers may be visiting internationally. It is also particularly important to follow the principle of visibility because of the increasing average age, and thus vision difficulties, of drivers.
- Ministry of Transportation of Ontario. (2002). The Official Driver’s Handbook. Queen’s Printer for Ontario
- Preece, Jennifer; Rogers, Yvonne; Sharp, Helen. (2002). Interaction Design: Beyond Human-Computer Interaction. New York: John Wiley & Sons, Inc.
- Shinar, David; Dewar, Robert E.; Summala, Heikki; Zakowska, Lidia. (2003). Traffic Symbol Comprehension: A Cross-Cultural Study. Ergonomics 46(15), p 1549-1565
- - Ben-Bassat, Tamar, and David Shinar. (2006). Ergonomic guidelines for traffic sign design increase sign comprehension. Human Factors, 48(1), p 182-195
- Wickens, Christopher D.; Gordon, Sallie E.; Liu, Yili. (1998). An Introduction to Human Factors Engineering. New York: Addison-Wesley Educational Publishers Inc.
- Stridger, Ruth W. (2003). How Readable Are Your Street Signs? Better Roads, 73(8), p 36-38
- Ministry of Transportation of Ontario
- Magic Roundabout
- Traffic Control Signs Designs Over Time
- Manual of Standard Traffic Signs and Pavement Markings
- Researched-Based Web Design & Usability Guidelines
- Asked Questions
- Driving School Ireland
- Traffic Signs Regulations for the United Kingdom
- Traffic Signs Manual for the United Kingdom