With the development of modern science and automobile technology, the number of cars has increased, and the conflicts at intersections have intensified. In order to pass through intersections safely and quickly, people have to use the latest scientific and technological achievements to solve the traffic jam problem at intersections, thus promoting automatic control technology. Rapid development in the field of transportation. The experience of traffic management in various countries in the world shows that one of the most effective methods of traffic management at road intersections is traffic signal control. Therefore, signal light control is also the most common form of traffic management at road intersections. Practice has proved that any traffic signal control system can exert the control efficiency of the system and achieve the predetermined control goal only if it is combined with the local and actual traffic conditions at that time, continuously optimizes the signal timing, and uses new technologies to continuously innovate the signal control mode.
Article | Lee Dae Sung
Full text 4 6 00 , expected to read 12 minutes
(one)
The emergence and development of traffic signal control
In 1886, Westminster Abbey in London installed a red and green gas lighting lamp to direct the passage of horse-drawn carriages at intersections. Unfortunately, after a period of operation, an accidental explosion occurred, causing people to oppose and die.
In 1917, Salt Lake City in the United States began to use a linkage signal system, using 6 intersections as a system to be controlled manually.
At the beginning of 1918, a new manual red, yellow and green three-color signal lamp appeared on the streets of New York, USA, which was very similar to the current signal machine.
In 1922, a synchronous control system was established in Houston, USA, which controlled several intersections with a sentry box as the center.
In 1926, the first automatic traffic signal machine was built in London, England and used on the street, which can be said to be the beginning of the automatic control signal machine for urban traffic.
In 1928, people made a "flexible step-by-step" timing system on the basis of the above-mentioned various signals. Because of its simple structure, reliability, and low price, it was quickly popularized. After continuous improvement, update, and perfection, Developed into the current traffic coordination control system.
The development of computer applications is also very fast. First, the analog electronic computer was first installed in Denver, USA in 1952. After improvement, it was called "PR" system (Program Register). By 1962, more than 100 "PR" systems had been installed in the United States. "system. Then digital computers also entered the field of traffic control. In 1963, Toronto was the first to complete the urban traffic control system (UTC system) with a digital computer as the core, and then Western Europe and Japan soon established improved UTC systems.
In terms of software development, in 1967, experts from the British Transport and Road Research Laboratory (TRRL) developed "TRAN-SYT" (Traffic Network Study Tool). It is a timing program optimized for off-line simulation. It is widely used and works well. It has been continuously improved and improved, and now it has released the 17th edition.
However, because the TRANSYT timing scheme is based on historical data, it cannot be changed in a timely and effective manner with changes in traffic flow. In 1980, the British TRRL proposed the SCOOT (Split Cycle Offset Optimization Technique) real-time self-adaptive traffic control system. The vehicle arrival information collected by the installed vehicle detector is processed online to form a control scheme, and parameters such as green signal ratio, cycle length and time difference can be adjusted in due course to adapt to the changing traffic flow. The social and economic benefits produced by it are about 10% higher than that of TRANSYT (Version 8) fixed timing system. At the same time that SCOOT was launched, Sims (AGSims) of the New South Wales Arterial Road Bureau in Australia also developed a SCATS (Sydney-Coordinated Adaptive Traffic System) control system and began to apply it in Sydney. It is a real-time self-adaptive control system that can choose a scheme.
The above three systems are relatively well-known traffic control systems that are commonly used today. There are still many control software developed or used in other places, but they have not been applied in a large range.
(two)
The Beginning of Urban Traffic Signal Control in my country
my country's urban traffic control research work started relatively late, starting from the use of single-point fixed-period traffic signal controllers to control traffic lights in several cities. In 1973, Beijing launched my country's first urban traffic automatic control project - Capital Automated Traffic Control Project (also known as Beijing Qiansanmen Street Traffic Signal Automatic Control Project or 7386 Project), conducts experimental research on the coordinated control system of traffic trunk roads in Qiansanmen Street. In 1978, Guangzhou, Beijing, Shanghai and other cities began to develop and use single-point fixed-period traffic signal controllers; in 1985, the National Urban Traffic Management Work Conference was held in Guangzhou to promote the application of automatic traffic signal controller mode in Guangzhou, that is, to use fixed configuration In 1986, at the National Public Security Computer Application Exhibition, the computer traffic signal developed by Guangzhou won the third prize of National Public Security Computer Application together with the computer traffic signal developed by Beijing and Shenyang. The computerized traffic signal machine can perform inductive traffic signal control according to the traffic flow detected by the vehicle detectors in all directions at the intersection.
my country's traffic control system research and development began in the 1980s. The "Urban Traffic Real-time Adaptive Control System" ("2443" Project) developed by the country's "Seventh Five-Year Plan" key scientific and technological research and development is the first real-time traffic control system developed by my country. The self-adaptive urban traffic control system has generally reached the international advanced level at that time, and the regional traffic coordination control demonstration application has been carried out at 24 intersections in the central district of Nanjing. The "Urban Traffic Control System Application Technology" developed by the country's "Eighth Five-Year Plan" key scientific and technological research and development focused on solving the engineering technical problems of the traffic control system and provided relatively mature technology and equipment. The system software was also transplanted from AT&T UNIX to Microsoft Windows NT platform, selected for demonstration application in Tianhe District, Guangzhou. The national "Ninth Five-Year Plan" scientific and technological research project "Research and Demonstration Project of Key Technologies to Alleviate Urban Road Traffic Congestion" has developed a traffic signal control system and a traffic dynamic information system. Later, with the advancement of science and technology, many universities and companies, or based on various research programs at the national, provincial and ministerial levels, or spontaneously developed many systems such as traffic signal control systems, which have been partially applied in some cities. In the 1980s, with the introduction of international advanced traffic signal control systems such as SCOOT and SCATS in some large cities in my country, my country's road traffic entered the stage of traffic signal control system with coordinated control of points, lines and surfaces. During this period, it was mainly concentrated in big cities. Through the introduction and application of foreign advanced systems, assimilation and absorption of traffic control technology, it accumulated relevant experience for my country's independent research and development.
Since the 1980s, my country has developed and established a control system suitable for the characteristics of China's mixed traffic flow. The more representative systems are HT-UTCS and Hicon systems. The HT-UTCS system is a real-time self-adaptive system independently developed by the Ministry of Transport, the Ministry of Public Security and Nanjing City. It adopts three-level distributed control (regional coordination, line coordination and single-point control). adapt to the control system. The Hicon system is an adaptive system developed by Qingdao Hisense Network Technology. It adopts a three-level control mode, including intersection level, regional level and central level control. The intersection level is responsible for real-time data collection, uploading to the superior, and receiving superior instructions; the regional level is responsible for the sub-area Control optimization, data collection, and traffic forecasting: the central level is responsible for monitoring the operating status of the lower levels and providing a human-computer interaction platform.
(three)
Application of my country's Urban Intelligent Traffic Signal Control System
Since the 1980s, most cities in my country have successively established traffic signal control systems. According to the survey in 2020, there are more than 71,800 light-controlled intersections with traffic signals in the central areas of 130 sample cities. Among them, there are 20 cities with more than 1,000 light-controlled intersections, 22 cities with 500-1,000 light-controlled intersections, and 88 cities with less than 500 light-controlled intersections. The survey shows that the connection rate of signal machines in the sample cities is uneven. Among them, only 17 cities have achieved full network connection, and another 25% of cities have a signal network connection rate of less than 60%.
Judging from the current situation in our country, the urban traffic signal control system plays a role in balancing the distribution of traffic flow in the road network and reducing the number of parking, delay time and environmental pollution in the application of coordinating and controlling urban areas. Practice has proved that any traffic signal control system can exert the control efficiency of the system and achieve the predetermined control goal only if it is combined with the local and actual traffic conditions at that time, continuously optimizes the signal timing, and uses new technologies to continuously innovate the signal control mode .
1. Optimization of timing parameters to maximize control efficiency
Whether the control strategy of the traffic signal control system is system timing control or adaptive control, its traditional signal timing either relies on experienced traffic management department business personnel to determine the timing duration, or relies on road surface coils, geomagnetism, video, etc. The vehicle detector collects dynamic data, and the traffic signal control system automatically adjusts the signal timing through its model algorithm or settings. At present, cities in our country are developing rapidly, and roads are frequently reconstructed in various places, especially large and medium-sized cities. Due to the lack of professional technical personnel, it is difficult to make the traffic signal control system effective. Since the publication of the "Work Plan for Promoting the Standardization of Urban Road Traffic Signs and Lines" and the "Work Plan for Promoting the Intelligent Timing of Urban Road Traffic Signal Lights" (referred to as "two modernizations" documents) issued by the Traffic Management Bureau of the Ministry of Public Security, the optimization of signal control timing Socialized services have also gradually begun to explode. In the past, they were mainly concentrated in developed areas such as Guangdong, Jiangsu and Zhejiang. Now some small and medium-sized cities have also begun to gradually develop the optimization of traffic signal timing parameters to "socialized" procurement services.
Optimize social services through traffic signal timing parameters. Professional social service companies implement signal ledger systems and signal control evaluation systems in their daily work, and use control calculations and single-point intersection timing calculation platforms to optimize timing parameters. The process not only considered the balanced channeling of road network traffic, but also carefully tapped the potential and improved the traffic efficiency of intersections/arterial lines. After the optimization of traffic signal timing in Guangzhou, Shenzhen, Jinan and other cities is handed over to social services, the fine management of traffic signal control optimization is realized, and the traffic capacity of intersections and arterial roads in the region is improved, thereby achieving the goal of alleviating traffic congestion and ensuring traffic Safe and realize the control effect of orderly traffic.
2. Perception technology upgrades to improve control efficiency
Front-end traffic sensing equipment is the source and data basis of traffic signal control. Real-time, accurate, all-weather and comprehensive perception of road traffic flow and traffic behavior through traffic flow collection equipment is an important goal of the traffic perception system. At present, the main traffic collection equipment includes: video, coil, geomagnetism, radar, RFID, and Leishi all-in-one machine.
According to the survey, 51 cities have installed video capture equipment, which is the most used collection method, accounting for 86%. 20 cities have installed geomagnetic acquisition equipment, and 19 cities have installed radar acquisition equipment, accounting for 34% and 32% of the sample cities respectively.
The perception technology upgrade can more accurately extract the traffic flow, vehicle size, speed, occupancy rate, queue length, and vehicle trajectory of the corresponding detection lane, and pre-set the traffic signal control scheme according to the traffic flow at the intersection and the vehicle trajectory to achieve the goal of the system. Optimum control efficiency. For example, the traffic signal control system in Qingyuan City, Guangdong Province, through the combination of section/area detection and trajectory detection, analyzes the carrying capacity of urban roads, grasps the characteristics of road network traffic flow trends, and controls traffic signals from the perspective of traffic demand and road resource supply. The method realizes the reasonable diversion of traffic, and uses the combination of the traffic simulation first evaluation method and the traffic matching degree, travel time and traffic delay, etc., to comprehensively plan and transform the intelligent signal control system, and optimize the signal timing to make the road pass Maximize efficiency.
(Four)
Prospects for Intelligentization of Urban Intelligent Traffic Signal Control System in my country
In recent years, with the expansion of the application of next-generation ICT technologies such as big data, cloud computing, artificial intelligence, Internet of Things, 5G Internet of Vehicles, mobile Internet, digital twins, and holographic intersections, urban traffic such as Tencent, Ali, Huawei, Baidu, and Didi With the emergence of brains and "Internet + signal lights", traffic signal control has also ushered in a new stage of intelligent development based on the integration of end, edge and cloud .
On the terminal side, the traditional intelligent traffic signal control system is mainly based on the collection of data such as traffic flow and occupancy rate by road vehicle detection equipment, and the control effect is directly subject to the integrity of the detection equipment. With the upgrading of technology, the perception data of road terminals can be enhanced and integrated through various new technologies such as video AI, RFID, lidar, Levision all-in-one machine, Internet of Vehicles, etc., and is no longer limited by the integrity of the original system's self-collected detection equipment. Instead, it is based on fusion analysis of multi-source and multi-dimensional big data that can be obtained at low cost anytime, anywhere, so that it can more accurately describe the traffic flow at intersections, queuing, release and other traffic status characteristics, and better realize traffic signal control. The Internet of Things system truly achieves "visible and clear" traffic in all time and space .
On the edge side, through the transplantation of new technologies such as edge computing, machine learning, neural network, and AR, the system can no longer rely on complex data models with many formula variables and harsh boundary conditions in modern control theory, and can directly drive the intelligence of traffic signals by big data. Decision-making control and iterative learning, truly achieve "Thinking through and thinking well" in signal timing .
On the cloud side, through new technologies and applications such as holographic perception, data twins, high-precision maps, online car-hailing, and the Internet, online parallel simulation and real-time performance evaluation of traffic signal decision-making control can be realized, and real-time traffic control at the regional level can be truly achieved. Adaptive optimization iterations. Through the application of new technologies such as the Internet of Things, Internet of Vehicles, and mobile Internet, traffic signal control has gradually changed from post-traffic response to pre-guidance of traffic demand and active service of traffic information, truly realizing the full time and space of traffic elements such as people, vehicles, roads, and control. Efficient configuration and coordinated coordination .
With the advent of the 5G Internet of Vehicles era, the traffic signal control system will gradually transform from traffic control to traffic information services, promote more accurate and effective information service content, and adopt various means to push traffic signal control information to all travelers , only in this way can passive traffic signal control be transformed into active traffic signal control. The new generation of traffic signal control system will likely play a role in the realization of automatic driving, thereby promoting the large-scale application of vehicle-road coordination.
END
▎ " Talks about Internet of Vehicles" series
[5G Industry Application] The "Internet of Vehicles Hundreds of Talks" series launched by the official account invites industry experts and scholars to write in-depth analysis articles in the field of Internet of Vehicles, interpreting the standards, technologies, policies, industries, application scenarios, business models, and data open models of the Internet of Vehicles etc., explore the prospects, opportunities and challenges of the future development of the Internet of Vehicles industry, and look forward to promoting the development of the Internet of Vehicles industry.
▎Recommended reading
Internet of Vehicles Hundred Talks No. 04: Thoughts on Pain Points of Vehicle-Road Collaboration
Internet of Vehicles Hundred Talks No. 06: How LiDAR Empowers Vehicle-Road Collaboration
Internet of Vehicles Hundred Talks No. 11: The Status Quo and Challenges of V2X Pre-installed Mass Production
▎Good book recommendation
01
Published by People's Posts and Telecommunications Press, this book focuses on 5G and interprets edge computing from a point-to-plane perspective . On the basis of introducing the connotation and core technology of edge computing in the 5G era, it focuses on analyzing and introducing the situation of the edge computing industry chain and the application of seven typical industries of edge computing .
The industrial chain covers upstream, midstream and downstream . Typical industry applications include the transportation industry (autonomous driving, intelligent network connection, intelligent transportation, and smart roads), security industry, cloud gaming industry, industrial Internet, energy Internet, smart city, and smart home .
Dr. Wu Dongsheng Editor-in-Chief
Wu Dongsheng, Ph.D., Southeast University. He is currently the senior vice president of Gosuncn Technology Group Co., Ltd., the vice chairman of the Guangdong-Hong Kong-Macao Greater Bay Area Autonomous Driving Industry Alliance, the director of the Guangzhou Vehicle-Road Collaborative Industry Innovation Alliance, and the director of the Operation Center of the Guangzhou Intelligent Networked Vehicle Demonstration Zone. Committed to the research and application innovation of 5G, intelligent network connection, automatic driving, big data, artificial intelligence and other technologies. Published dozens of papers in provincial and municipal periodicals, edited books such as "5G and Internet of Vehicles Technology", participated in the compilation of "Guangzhou Intelligent Networked Vehicle and Smart Transportation Industry Development Report (2020)", etc.
purchase link
02
This book systematically analyzes the overall architecture, system standards, key technologies, typical services and application scenarios of 5G IoV, comprehensively scans and analyzes the latest developments in global and domestic IoV, and analyzes the challenges and challenges faced by the 5G IoV industry development. Prospecting and forecasting future development prospects is of reference value for practitioners who are committed to 5G and Internet of Vehicles industry research, standardization and related product realization.
purchase link
about Us
"5G Industry Application" is a research and consulting platform that gathers senior experts in the TMT industry. It is committed to providing enterprises and individuals with objective, in-depth and highly commercially valuable market research and consulting services in the 5G era, helping enterprises to use 5G to achieve strategic transformation and business refactor. This official account focuses on providing the latest developments and in-depth analysis of the 5G industry, covering communications, media, finance, automobiles, transportation, industry and other fields.
