Traffic Signs & Information

The "Manual on Uniform Traffic Control Devices" defines the standard traffic signs in the U.S.

Traffic signs and pavement markings convey important regulatory, warning and guidance information to motorists and all others users of a roadway. When traffic engineers designed the system of traffic signs for highways and local streets, it was not only the text of the message, but the shape and color of the sign panel that were considered in helping drivers readily recognize and respond to the needed action.

Standardized Traffic Signs

Years ago, traffic signing varied widely across the United States. That is no longer the case--thanks to the federal requirement that all roads open to public use must conform to the signing and pavement marking requirements of the "Manual on Uniform Traffic Control Devices" (MUTCD). Traffic signs are purposely designed to be simple in design, uniform in shape and color, and readily recognizable.

Types of Traffic Signs

There are a number of different types of roads signs including regulatory, warning, guide, toll road, preferential lane, temporary traffic control and school signs.

Regulatory signs are used to inform motorists of traffic laws. These signs include stop, yield and speed limit signs. Warning signs alert drivers of unexpected roadway conditions and include curve, merge and ramp speed signs.

Guide signing includes highway route markers (such as the interstate highway shield) and the large, green signs seen on freeways and expressways. Toll road signs are used on roadways that use toll plazas or other fee collection points. Preferential lane signs, seen on highways and arterials, are used for special lanes such as carpool lanes or lanes used exclusively by buses.

Temporary traffic control signs are an important category of signs used to guide traffic through road construction zones. School signs are specially designed signs for use in the vicinity of schools.

Other signs are used for recreational areas, for railroad and light rail crossings, to mark highway obstructions and for bicycle trails.

Shapes and Colors

Sign shapes and colors are an important part of making each sign readily recognized by motorists, especially those traveling at high speeds. Each type of sign is assigned a limited set of shapes and colors. For example, diamond-shaped signs are typically reserved for warning signs. Brown is reserved for recreational area signs. And, of course, the octagon shape is reserved for stop signs. Regulatory, warning and guide signs must also be retroreflective to be visible both day and night.

Signing and Pavement Markings Work Together

Pavement markings, traffic signs and traffic signals all work together to guide road users.

Signs are not the only means for guiding motorists along the road. Pavement markings also play an important role in providing guidance and information to road users. Pavement markings are used to define lanes of travel, separate the paths of vehicles traveling in opposite directions, show locations of exclusive turn lanes, define the edge of the roadway, and identify roadway segments for passing/no-passing zones. While yellow and white are the most commonly used pavement marking colors, other allowed colors for specific applications include red, blue, purple and black.

Some Changes Ahead

The Federal Highway Administration (FHWA) issued the current edition of the "Manual on Uniform Traffic Control Devices" in December 2009. Among the changes made in this latest edition are many new types of signs including new signs for light-rail crossings and at roundabouts. Purple can now be used as a background color on toll roads. There are also numerous changes to construction work zones, intended to make work areas safer for both motorists and construction crews.

References

• "Manual on Uniform Traffic Control Devices"; Federal Highway Administration; 2009