Research On Mixed Non-motorized Flow Simulation Based On Social Force Model

Bicycle and electric bicycle travel play an important role in the urban travel structure,and the mixed flow composed of them has become the main manifestation of the current non-motorized line.However,its traffic environment is not optimistic.There are too many problems,such as the imperfect supporting facilities,the encroachment on right of way and so on.Furtherly,the electric bicycle brings more frequent and serious vehicle conflicts because of its high speed and acceleration,which makes the non-motorized flow more complex.Therefore,studying individual vehicle and mixed flow characteristics,establishing and improving non-motorized vehicle simulation model are of great significance to improve the micro movement behavior and macro traffic flow theory of non-motorized vehicle,as well as guide the operation management and facilities construction of non-motorized vehicle.This paper takes the basic section of the non-motorized vehicle lane as the research scope,assuming that the section is smooth,without retrograde and influence of other participants,and takes the non-motorized mixed flow composed of bicycles and electric bicycles in the section as the research object,constructs the micro simulation model of non-motorized mixed flow.The specific work is as follows:(1)The macro and micro traffic characteristics of non-motorized vehicles are summarized and analyzed.Using the data collected from three non-motorized lanes,Chegongzhuang Street,Shouti South Road and Xizhimen South Street,cyclist and vehicle attributes,arrival distribution,parallel and surpassing proportion of non-motorized vehicles are summarized.In addition,mainly considering proportion of electric bicycle,categories of non-motorized vehicle,riding states,boundary forms and lane width,the horizontal spacing,lateral distance,headway,riding track,speed and density,acceleration and deceleration are analyzed.(2)A micro traffic simulation model based on Social Force is established.Comparing and analyzing related non-motorized vehicle models at home and abroad,Social Force Model is then determined as the main simulation method.Furtherly,the individual unit composed of human-vehicle system and its perception domain is constructed to optimize the force range and improve the calculation efficiency of the model.The influence of different forms of boundary on non-motorized vehicles is refined so as to optimize the boundary force.At the same time,overtaking force is proposed from formula and mechanism to make up Social Force Model's imperfect description on transcendence behavior in non-motorized mixed flow.Through the above-mentioned work,combined with traditional driving force and repulsive force,the micro simulation model of the non-motorized mixed flow is finally constructed.Based on Python,the micro simulation platform is built,then the validity of the model is verified from the simulation scenario and basic diagram.(3)All parameters of the simulation model are calibrated.on the basis of measured data and existing research results,the calibration process of model relevant parameters is described one by one.Especially,calibrate the key parameters supporting model improvement,such as the lateral response coefficienta_i,the longitudinal response coefficient ?_i',the boundary force intensity ?_i,the expected speed coefficient and the transcendental vector (?)(t).(4)Debugging different simulation scenarios via Python simulation platform,single flow and mixed flow are respectively studied to provide suggestions for operation and management of non-motorized vehicle.In terms of single flow,capacities under different boundaries are obtained.The reduction coefficient of boundary to capacity and the conversion coefficient of electric bicycle to bicycle are further analyzed and calculated.In terms of mixed flow,taking the non-motorized lane with roadside parking on the left side and physical isolation on the right side as an example,capacities under different widths and proportions of electric bicycle are simulated.The relationship between capacity,single lane capacity,lane width and electric bicycle proportion is found.At the same time,the overtaking times of 3m non-motorized lane under different flow and proportion of electric bicycle are studied.