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Traffic control
- Dec 06, 2018 -

Traffic control

Traffic control, also known as traffic signal control, or urban traffic control, is the use of traffic police or traffic signal control facilities, with the characteristics of traffic changes to command the passage of vehicles and pedestrians.
Traffic control USES modern communication facilities, signal devices, sensors, monitoring equipment and computers to accurately organize and regulate the running vehicles so that they can operate safely and smoothly. Traffic control is divided into static management and dynamic management, and traffic control is the dynamic management.

Origin and development
The research of urban traffic control has an early origin.
In 1868, the advent of London gas signal lights marked the beginning of the use of urban traffic signals.
1913 the world's first traffic signal control system was introduced in Cleveland, Ohio.
In 1917, Salt Lake City in the United States began to use the linkage signal system, six junctions as a system, with manual control.
In early 1918, new manual red, yellow, and green lights appeared on the streets of New York City, much like today's signal machines.
In 1922, Houston used the first automatic traffic signal in the street, which was the beginning of the automatic traffic control signal in the city.
In 1926, the city of Chicago in the United States adopted the traffic light control scheme, with a unique traffic light at each intersection. Since then, traffic control technology and related control algorithms have been rapidly developed and improved, improving the safety and effectiveness of traffic control and reducing the impact on the environment.
In the 1930s, pneumatic rubber tube type vehicle sensor signal controller was produced in the United States and Britain to detect traffic flow and adjust the green light duration.
In the mid-1970s, an inductive traffic signal controller was developed in Beijing.
In the 1980s, Beijing, Shanghai and other big cities successively developed computerized signal control machine and trunk line coordination control system.
Modern information technology, electronic technology, automatic control technology and the development of computer technology make the lights as the main body of the traffic control means of rapid development, the traffic signal from manual to automatic, traffic signal by a fixed cycle to cycle, variable control method by point control, line control system to control, and for the development of intelligent traffic control system.
Toronto, Canada, established a centralized coordinated induction control signal system using IBM650 computer in 1963. Later, the United States, the United Kingdom, the former federal republic of Germany, Japan, Australia and other countries have built computer regional traffic control system, this system is generally equipped with traffic monitoring system to form a traffic management center.
Until the early 1980s, there were more than 300 cities around the world with traffic control centers. TRANSYT, SCOOT system and SCATS system developed by Australia are the most representative urban road traffic control systems widely used in various countries.
In recent years, Britain, Australia, Europe and the United States have established traffic control systems in some cities. In these systems, most of the intersection near the installation of magnetic loop detector, and by the intersection of the control device or staff will traffic control parameters through telephone lines, cables, closed-circuit television lines and other communication network input microprocessor, with a small computer for centralized control.
At present, there are some independently developed urban traffic control and management systems in China, but there is still a big gap in the overall performance compared with similar systems in foreign countries, which are only applied in some small and medium-sized cities. Most of the transportation systems introduced by domestic cities, especially large cities, are imported SCOOT and SCATS systems. Because our country traffic flow is mixed traffic flow, and foreign traffic flow is very different, the use effect of foreign traffic control system in China is not satisfactory. Compared with foreign countries, China's current traffic situation is relatively backward, mainly reflected in:
(1) the urban road structure is unreasonable. Most urban road space structures belong to the plane traffic state, forming the characteristics of "mixed traffic between people and cars, and mixed traffic between fast and slow cars". The proportion of main and secondary trunk roads to branch roads is out of proportion and the connection between them is out of order, making it difficult for trunk roads to play their functions. In terms of road area, the rate of urban road area in China is lower than that in large cities of the same size in the world.
(2) unbalanced traffic structure. Domestic urban traffic is mainly composed of various motor vehicles, non-motor vehicles and pedestrians, forming a special ternary mixed traffic structure.
(3) low technical level of traffic management and frequent traffic accidents. At present, there are two typical problems of urban traffic in China: poor management and disorder; There is no scientific, reasonable and effective urban traffic monitoring system. The consequence that brings from this is increasingly serious. The road network capacity is significantly lower than the design requirements and fluctuates greatly, the travel time is difficult to predict, high incidence of traffic accidents, traffic environment deterioration, travelers easy to fatigue, etc.