Road traffic control device

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.
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.
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 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 eight feet (2.4 m). 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 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.
Road surface markings are traffic control devices that are applied directly to the road surfaces. They are used to guide and channel traffic by designating lanes and indicating stopping points at intersections. Pavement markings may be permanent or removable.
Rumble strips are roughened surfaces that are either embossed or recessed. When a vehicle drives over them, they make a loud rumbling sound and vibration. They can be placed across traffic lanes to alert drivers that they are approaching a potentially hazardous location, such as a work zone, school zone, rail road crossing or an isolated intersection. They are used along the shoulders or centerlines of highways to alert drivers that they are leaving their traffic lane.
Traffic lights are traffic control signals used to alternately assign right-of-way to traffic moving in conflicting directions at an intersection. Traffic lights feature three different lights that conveys different meanings. The red light means that the vehicle facing the traffic light must come to a complete stop. A green light means that the vehicle facing the traffic light may proceed when it is safe to do so. A yellow light indicates that a red light will follow, and vehicle drivers must stop if it is safe to do so.