Research On Route Optimization Problem Of Pedestrian Evacuation For Car-free Zone

With the rapid development of urbanization and the improvement of people's material and cultural level,facing a series of urban problems such as traffic congestion,air pollution and frequent traffic accidents caused by car traffic,urban residents began to pursue a high-quality living environment and travel mode of human-oriented,green safety and ecological health.In order to meet the increasing and diversified travel needs of people,the car-free zone,which limits the use of motor vehicles and mainly serves for walking,as the gathering point and activity point of large-scale population,has significantly improved both in scale and quantity.The rise of car-free zones and the consequent dense population,while enriching the material and cultural life of residents and bringing about a great growth of consumption,also has a large number of potential security risks.At present,the research of pedestrian emergency evacuation at home and abroad mainly focuses on the pedestrian facility interior and evacuation simulation model,and less attention is paid to the pedestrian evacuation characteristics and evacuation path planning in the car-free zone under the emergency.Therefore,based on the research background of pedestrian evacuation in car-free zone,aiming at the characteristics of pedestrian evacuation in car-free zone,a scientific and reasonable theoretical method of pedestrian evacuation path planning in car-free zone is proposed to realize the safe,effective and rapid evacuation of pedestrians in car-free zone,which has important theoretical value and practical significance for promoting the development of car-free zone and ensuring the safety of public areas.Based on the above considerations,this paper studies the optimization of pedestrian evacuation path in car-free zone,and the main work is as follows:(1)This paper introduces the research background and significance,summarizes the research status of the development of car-free zone at home and abroad,the research status of pedestrian emergency evacuation and the research status of evacuation path optimization,and puts forward the research content and technical route of this paper.(2)Introduce the basic theory of the paper.On the basis of relevant theoretical analysis,the basic principle of user equilibrium theory,mathematical planning model,path impedance function and Frank-Wolfe algorithm are introduced.The definition,composition and application of cellular automata are introduced in detail.The influencing factors of pedestrian evacuation are summarized from two aspects of self factors and environmental factors.(3)Study the evacuation characteristics of pedestrians in car-free zone.The development and definition of car-free zone are given.According to the different nature of the land,the carfree zone is classified and explained.Taking the pedestrian evacuation in car-free zone as the research object,the pedestrian evacuation characteristics in car-free zone are described from two aspects: the road network characteristics and the characteristics of the evacuees,providing theoretical basis for the model construction.(4)Based on the user equilibrium,the optimal selection model of pedestrian evacuation path in car-free zone is constructed.Based on the basic idea of graph theory,considering the characteristics of pedestrian evacuation in car-free zone,a pedestrian evacuation network in carfree zone is established.Combined with the user equilibrium theory of Wardrop,from the point of view of evacuating people,taking the shortest evacuation time as the objective function,the optimal selection model of pedestrian evacuation path in car-free zone based on user equilibrium is established.Based on the theory of cellular automata,considering the impact of crowding on pedestrian evacuation,the evacuation time model based on cellular automata is established,and the reliability of the model is verified by the actual data.Combined with the evacuation time model,the Frank-Wolfe algorithm is improved,and the model solving algorithm is given.(5)Analyse the calculation example.Taking a car-free zone as an example,by determining the road network parameters,the pedestrian evacuation network in the car-free zone is constructed,the evacuation path planning in the car-free zone is carried out by using the evacuation time model,and the key nodes of the road network are determined;the effectiveness of the pedestrian evacuation path optimization method is verified by comparing and analyzing the evacuation results before and after optimization under various conditions.(6)Summarize the main conclusions of this paper,and prospect on the research direction in the future.