In the United States, Canada and Australia signs are categorised as follows:

• Regulatory signs
• Warning signs
• Guide signs
• Street signs
• Route markersigns
• Expresswaysigns
• Freewaysigns
• Welcome Signs
• Informational signs
• Recreation and cultural interest signs
• Emergency management(civil defense) signs
• Temporary traffic control (construction or work zone) signs
• Schoolsigns
• Railroad and light rail signs
• Bicycle signs

Here we have some samples

Warning Signs
Intersection with Tramway	Traffic Signals			Falling Rocks	Crossroads
Level Crossing with Barrier  (Road crosses railway tracks)	Level Crossing with Barrier  (Road crosses railway tracks)			Uneven Road	Slippery Road
Right Hand Curve	Left Hand Curve			Bend In Road	Danger
Deer Crossing	Livestock Crossing			Children Crossing	Men at Work
Prohibitive Signs
Turn Right Area		Straight Ahead		One Way	End of Build Up
Pass on Righthand Side  (Arrow pointing opposite way:  Pass on Left)		Stop Junction Ahead		Wait for Counter Traffic	Stop
No Turning		No Overtaking		No Entry	No Stopping
No Motor Vehicles		No Parking		Speed Limit	No Trailers
Informative Signs
Parking		Parking Disc Zone	Motorway		End of Motorway
Roundabout		Motor Vehicles Only	No Motor Vehicles		Dead End
Passing Place Road		Bus Lane	Priority Road		End of Priority

Road signs use shapes, colors, words, and symbols to communicate a message to drivers. Without such signs, the movement of traffic would be disorderly and unpredictable. Virtually all traffic signs use retroreflective sheeting, which is designed to reflect some of the light from vehicle headlights back to the driver so that the sign will be visible at night. Color and shape can also provide cues to motorists even when the words or symbols on the sign are unintelligible. Regulatory signs, such as speed limit signs, are usually rectangular and use a white background. Stop signs, on the other hand, have a distinct octagonal shape and a red background in order to catch the driver's eye.

Designers must utilize elements like shape and consider material properties in creating signs that drivers can see and understand in time to react appropriately. Contrast, which is a measure of the brightness of the message in relation to its background, is an important property of any sign. The environmental backdrop—usually green vegetation and blue sky—must also be considered in the design process. A border is placed around all signs to distinguish them as geometric shapes in contrast to nature.

Raw Materials

Traffic signs consist of three basic components: a blank, background sheeting, and sign copy. Blanks, usually constructed of plywood, aluminum, or steel, serve as the framework of the sign. Plywood is the least expensive blank material. It is fairly strong but is susceptible to weather damage since it is porous; plywood blanks must be overlaid with a thin layer of plastic. Aluminum will not rust, but it is very lightweight and must be reinforced with metal braces along the back. It is the most expensive blank option. Steel is a more economical alternative to aluminum; it is also more sturdy and does not need reinforcement. Rusting can be prevented by applying a coat of zincto the steel blank.

Background sheeting and the letter and symbols for the sign copy are cut from retroreflective sheeting. This sheeting consists of tiny glass beads or microprisms embedded in a flexible plastic surface; this construction allows light from car headlights to be reflected off the sign and back to the driver. Colored light is reflected from the sign if the sheeting is dyed with a pigment. For instance, to make "STOP" signs, red dye can be added to the sheeting mixture when it is in a liquid form.

The Manufacturing

Process

The production of signs can involve many different processes, depending on whether the retroreflective sheeting uses a heat-sensitive or pressure-sensitive adhesive and whether silk-screening, etching, or other coloring processes are used. Many traffic signs, however, undergo the following process using heat-sensitive adhesives.