Road traffic control devices are markers, signs and signal devices used to inform, guide and control traffic, including pedestrians, motor vehicle drivers and bicyclists. These devices are usually placed adjacent, over or along the highways, roads, traffic facilities and other public areas that require traffic control.
Types
Signs
Traffic signs are signs which use words and/or symbols to convey information to road users. These devices are made with retroreflective materials that reflect light from headlights back towards the driver's eyes. This is to achieve maximum visibility, especially at night.
Traditional
Regulatory signs are traffic signs used to convey traffic rules and regulations such as intersection controls, weight limit, speed limit, one way, no parking and others. These signs are generally rectangular in shape and use white, black and red/or as their primary colors. Warning signs are traffic signs that are used to warn road users about a potential danger. These signs are usually diamond in shape and, except for temporary traffic control signs, have black legends and borders on a yellow background. Work zone signs have orange backgrounds, and incident management signs have pink backgrounds. Examples of warning signs are crosswalk signs. curve warning signs, intersection ahead signs, flagger signs, workers signs, or road machinery signs. Guide signs help road users navigate to their destination. These signs are generally rectangular in shape and have white text on green backgrounds. When a guide sign provides temporary guidance due to a work zone, it will have a black legend and border on an orange background. Examples of guide signs are street name signs, destination and distance signs, and place name signs. Work zone guide signs include detour markers, length of work signs, and end road work signs.
Variable
Variable-message signs, or VMS, are electronic traffic control signs which can display different traffic messages according to the needs of a specific road. Permanent VMS displays are mounted on large sign structures overhead or alongside the road. These devices are often placed on urban freeways which have traffic problems. Portable CMS (PVMS) panels are usually mounted on trailers, although some may be carried by trucks. They are often used in work zones or other events that disrupt traffic. CMS devices also follow a uniform shape, design and color that were set by the Manual on Uniform Traffic Control Devices.
High-level warnings
High-level warning devices are traffic control devices that are high enough to see over other vehicles, such as vehicle roofs, poles, and other places not lower than . These devices are also called "flag trees" because they feature two or three square fluorescent orange flags and, sometimes, a flashing warning light. This type of traffic control devices are used in work zones in high traffic density urban areas.
Channelizing devices
Channelizing devices are used to warn drivers and pedestrians and to guide them through a work zone. Common channelizing devices are traffic cones and drums. These types of traffic control devices are usually placed between traffic and road construction zones, or between opposing traffic streams.