Intelligent Transportation System

Detailed introduction of aligreencom Intelligent Traffic System
Http://rise.cd-china.net/lanmu/bumen/kaifa/lvtong.htm
Development of Intelligent traffic signal control panel based on ARM
Http://article.ednchina.com/2006-07/2006740942021.htm

Background: Urban Road Traffic Management System (urtms) it is composed of multiple subsystems, including road traffic monitoring system, dynamic traffic information detection system, comprehensive road information analysis and processing system, intelligent traffic signal control system, vehicle satellite positioning system, and traffic management and command system. integration.

Urban road intelligent traffic signal control system

Urban road intelligent traffic signal control system

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The intelligent traffic signal control system is a subsystem in the urban road traffic management system that uses signal control for intersections, pedestrian crossings, and loop entrances and exits, it is an application system that uses multiple disciplines such as traffic engineering, psychology, applied mathematics, automatic control and information network technology, and system engineering. It mainly includes traffic engineering design, vehicle information collection, data transmission and processing, and control model.AlgorithmAnd simulation analysis, optimization of control signals to adjust traffic flows, etc. The existing traffic signal control systems in domestic and foreign large and medium-sized cities are established based on the planning and development level of their respective urban roads according to different environmental conditions. The second-level project "Urban Traffic Monitoring System" set up in the "information technology and high-performance software" of the national key basic research plan (973) project, combined with the characteristics of China's urban traffic development, the development direction of Intelligent Management for establishing a real-time adaptive traffic signal control system for urban roads is determined. Basic Components of intelligent traffic signal control system The basic components of the intelligent traffic signal control system are the main control center, intersection traffic signal control machine and data transmission equipment. The master control center includes the operating platform, interactive data warehouse, benefit indicator optimization model, and data (image) analysis and processing. For detailed structure, see. Framework of smart traffic signal control system for urban roads Core of intelligent traffic signal control system The core of the intelligent traffic signal control system is the control model algorithm software, which is a management platform for signal control policies throughout planning and design. It reflects the control ideology of traffic managers, it includes the function and position of the signal control system. Currently, most of the signal control systems that have been used at home and abroad are based on optimizing the periodic scheme, optimizing the green signal ratio of intersections, and coordinating the traffic capacities of relevant intersections, it is a passive control strategy that selects an appropriate signal ratio control scheme based on historical data and automatically detected traffic information through the set control model algorithm. The SCOOT system (split cycle offset optimization technique) developed by the British Institute of Transport and Road research (trrl) is used as the core software to optimize benefit indicators) and the SCATS system developed for the application background in Sydney, Australia, which was an early representative of Dynamic Real-time adaptive control systems, it is also the basis for the intelligent development of the traffic signal control system in the future. With the development of network technology, interactive control strategies enable real intelligence for signal control from sensory control to guidance. The traffic signal control system can not only detect traffic information parameters such as traffic flow, regulate the green signal ratio at intersections, change traffic restrictions, prohibitions, and other traffic signs, and complete information exchange with traffic participants based on the data warehouse connected by the system, displays Road Traffic Information and parking lots information to traffic participants, and provides reasonable routes to traffic participants to achieve active control strategies for balancing road traffic load. In particular, the computer network technology and digitization have ensured reliable data transmission and information utilization. It can be said that the intelligent traffic signal control system of urban roads is a comprehensive product of the rapid development of information industry technology in urban road traffic management. Main terms and parameters of traffic signal control system Cycle: it refers to the time required for displaying a cycle when the color of the signal lamp changes. It is also called a long cycle, that is, the sum of the red, yellow, and green time. Phase: the signal phase. It refers to a sequence group of one or more traffic flows that are manually set during the cycle and obtain the right of access at the same time. Phase Difference: the start time difference between two related phases in the same direction at the intersection with the same cycle length, which is called the phase difference. Green ratio: the ratio of the green time and cycle length of each phase within a long cycle. Saturated traffic: it is an important parameter to measure the traffic flow cast ability at an intersection. It usually refers to the maximum traffic flow continuously passing through the intersection during a green time. Traffic coefficient: the ratio of actual traffic to saturated traffic. It is not only an important parameter for calculating signal configuration, but also a measure of the degree of congestion at intersections. Green Time Interval: refers to the time used to start from the end of the phase in which the permission is lost to the next phase in which the permission is obtained. Valid Green Time: indicates the actual vehicle traffic time that is effectively used. It is equal to the sum of the green light time and the yellow light time minus the loss time of the start of the head car. Delay: The time loss caused by traffic conflicts or restrictions on signal control facilities. It is an important parameter for calculating the signal timing and measuring the traffic at the intersection. It is also an important parameter for determining the performance of the signal control system. Main Control Methods of intelligent traffic signal control system Coordinated Control of multiple phase signals during single-point configuration (preset clock call scheme, Traffic Conflict point reduction, early disconnection and delayed start) Real-time adaptive control of vehicle induction (adjustment cycle, green ratio, effective green time is added. The user is given priority to coordinated control without cable trunk lines (coordination cycle and phase difference, taking care of pedestrians, buses, and special vehicles) real-time adaptive area control (Traffic Flow Simulation, optimization benefit indicators, and balanced regional traffic flow) Steps for grading the intelligent traffic signal control system The original traffic flow data is designed and analyzed based on the current situation and Forecast of traffic flow at intersections. The control mode is determined based on the simulation model validation, configure traffic parameters according to the design requirements of traffic channelization design and control mode, and complete the traffic engineering design (including the detection area location of vehicle detectors) based on the correlation of the equipment configured at each intersection, complete the Coordination Design and determine the optimization target function of the system and single point of control, obtain the optimal signal control scheme, configure the solid basic parameters of the intersection signal control machine, and configure the master control center database and data transmission settings. Intelligent traffic signal control system operation management and hierarchical control The operation management of the signal control system mainly includes updating the data on the operating platform of the master control center database, including geographical information, and servicing and implementing the intersection facilities, especially the vehicle detection equipment, ensures integrity and accuracy. Because the construction of the traffic signal control system is closely related to urban planning and road planning, the construction and improvement of facilities are subject to certain constraints, and it is impractical to implement one-step traffic signal control system, the management mode of the intelligent traffic signal control system is centralized management, hierarchical control, full use of existing facilities, adaptive coordination of a single intersection according to the actual traffic status, and then coordinated control of the main trunk line, achieve distributed and coordinated hierarchical control, and ultimately achieve the optimal regional control system. Conclusion The intelligent traffic signal control system is indeed a professional and comprehensive application system that solves the most direct basic problems in our daily life. Everyone can give their views and opinions, however, it is difficult for everyone to systematically explain the cause of the problem and find a solution to the problem. Professionals can design ideal models and algorithms to differentiate the cognition and cultural level of traffic participants, so that the actual effect is not optimistic. Therefore, the technical knowledge of traffic management is popularized, increasing tolerance and understanding of the traffic status quo will promote the gradual improvement of the intelligent traffic signal control system, so that people can enjoy the fun of intelligent traffic as soon as possible. Question 1: What is the phase difference? Answer: There is a time difference between the start of two related phases in the same direction at the intersection with the same cycle. Question 2: Can traffic flow simulation play a role in the real-time adaptive coordination control system? Answer: Yes. Traffic flow simulation can be used to analyze and simulate historical data to provide a basis for the design of traffic canalization and traffic models. It can also be used for Dynamic Traffic Flow Simulation Based on the traffic data collected by the vehicle detector, make future traffic forecasts for the region and optimize the system control model. Question 3: What is the most basic work for the Hierarchical Design of the Intelligent traffic signal control system? Answer: design the traffic channelization based on the current situation and Forecast of traffic flows at intersections.