New Variable Speed Control Approach For Freeway

Freeway is constructed for the purpose of providing a fast, safe and smooth services to passenger and freight vehicles, but the speed, safety and smooth flow are always in contradiction. The drivers always expect to obtain high speed and efficient transport efficiency as much as possible according to the road and traffic conditions, however, traffic accidents and traffic congestion are often caused as their choice of speed is often inappropriate. Now, the management and implementation of speed limit has become a matter of worldwide hot topic of human security.Over speed driving is the main reason for Freeway accidents, unreasonable method of speed limit as well as imperfect technology of speed control is imperfect and is the source of speed accident. With a strong nonlinearity, ambiguity and uncertainty, the transport system is a typical distributed system affected by many factors and the basic law within is difficult to accurately model and descript using mathematical approach. Therefore, static methods of speed limit and fixed the speed limit can not reflect the dynamic characteristics of the road traffic system, which intensified the contradictions among speed management, traffic safety and transport efficiency. Based on the character of inaccurate model or no model, intelligent control theory takes information as the basis for learning and reasoning and uses heuristics to guide the solution process of the non-traditional mathematical formulation process. From the above, the combination of advanced intelligent control technology, information fusion technology, intelligent information processing technology and traffic engineering is an effective way to solve the current problem and is also inevitable direction of the speed limit in the future.Firstly, based on the analysis of road traffic safety system, this article studies the relationship among driving behaviors, effect factors of high-speed road speed limit and road traffic system, analyzes the current main approaches of speed limits and their applicability, clarity the basic idea and mechanism of variable speed control.Secondly, using advanced intelligent control method, theoretical model of the variable speed control of Freeway is studied. A mainline speed control model of freeway is established based on immune genetic algorithm and fuzzy neural network, the coordination optimization control method of traffic volume control of ramp and variable speed limit control of mainline is also proposed.Thirdly, combining information fusion technology, intelligent information processing techniques and traffic engineering, a long-range transport speed control system is architected, within which speed collection, management and dynamic remote control, are discussed. A prototype simulation system based on ArcGIS is implemented, which can provide new insights and ideas for reasonable and scientific speed limit as well as traffic management strategy.The following aspects are studied in this article:1.Based on cognitive psychology and Ergonomics, various factors that affect the speed, the relationship among speed limits, driver behavior, accident probability and severity and relationship between speed limit and traffic congestion are analyzed. Current main approaches of speed limits and their applicability is summarized and basic idea and mechanism of variable speed control is clarified.2.A mainline speed control model of freeway is established based on immune genetic algorithm and fuzzy neural network, which can fit the Freeway speed characteristics of nonlinear dynamics in structure and features and overcome the defects of separation of optimization of structure and parameters in the past models, leading to a faster convergence speed and higher accuracy of the network. Simulation results show that the control method can adjust the control value of online traffic to adapt to different environmental changes and can better reflect the road conditions, weather, traffic status and the impact of vehicle speed, thus achieve variable speed control on Freeway, effectively reduce accidents and reduce driver driving strength.3.Considering the characteristics and applicability of ramp metering and variable speed limits, the coordination optimization control method of traffic volume control of ramp and variable speed limit control of mainline is established. Based on conclusions of traffic control simulation experiment, traffic control methods is proposed based on traffic volume, which can lead to a reasonable distribution and optimization of traffic flow and can provide scientific and feasible basis for traffic control decisions.4.A new, efficient speed control mode-Remote speed intelligent control system is proposed, and within which the overall design concept, main functions of the system and subsystems, working mechanism of each module are clear described and explained. The implementation method for the functions of information collection, dynamic management and remote control of speed is proposed. A prototype simulation system based on ArcGIS geographic information platform is developed. With the good performance, the system can provide new insights, ideas and engineering solutions for reasonable and scientific speed limits values for Freeway as well as traffic management strategy.