Traffic lights are indispensable equipment in urban traffic management. Their main function is to guide vehicles and pedestrians to pass safely and orderly through different colored lights. According to different classification standards, traffic lights can be divided into several types, which will be introduced in detail below from three dimensions: function, form, and application scenarios.
Traffic lights can be categorized by function as follows:
Motor vehicle traffic lights: These are the most common type of traffic lights, typically composed of red, yellow, and green lights to indicate prohibition, warning, and permission, respectively. Motor vehicle traffic lights are widely used on urban main roads and intersections, serving as core equipment for regulating vehicle traffic order.
Non-motor vehicle traffic lights: These are traffic lights designed for bicycles, electric bikes, and other non-motorized vehicles. Their light combinations and display logic are similar to motor vehicle traffic lights, but they may use different shapes or sizes to distinguish them. Non-motorized vehicle traffic lights are commonly found in dedicated non-motorized vehicle lanes or mixed traffic intersections.
Pedestrian traffic lights: These lights indicate when pedestrians should cross the street. They typically consist of two states: "stop" (red) and "go" (green). Some lights also have a countdown timer to help pedestrians judge the remaining time. Pedestrian traffic lights are often installed at crosswalks and around schools.
Directional traffic lights: Also known as arrow lights, these use red and green arrows to indicate the right-of-way for vehicles to turn left, go straight, or turn right. Directional traffic lights effectively reduce traffic conflicts at intersections and improve traffic efficiency.
Flashing warning traffic lights: Usually yellow, these lights flash to alert drivers to potential hazards or special situations ahead, such as road construction areas or school zones. Flashing warning traffic lights do not directly control right-of-way but serve as a warning.
Traffic lights can be classified by form as follows:
Pole-mounted traffic lights: The most common type, these lights are mounted on poles and are suitable for most intersections. Depending on the installation method, pole-mounted traffic lights can be further divided into single-pole and double-pole types.
Cantilevered traffic lights: These lights are fixed above the road via cantilever arms and are suitable for wider intersections or scenarios requiring long-distance observation. Cantilevered traffic lights improve driver visibility and reduce obstruction of vision.
Gantt-type traffic lights: These consist of two uprights and a crossbeam. The traffic lights are mounted on the crossbeam, forming a portal-like structure. Gantt-type traffic lights are commonly used in scenarios requiring strict vehicle traffic control, such as highway toll booths and tunnel entrances.
Integrated traffic lights: These integrate multiple functions (such as signals for motor vehicles, non-motor vehicles, and pedestrians) into a single light unit, achieving comprehensive control through different light combinations. Integrated traffic lights simplify the equipment structure and save installation space.
