| Road section with mixed traffic flow is a long-standing component of urban roads in China,especially in small and medium-sized cities.Compared with the homogeneous traffic flow,the interaction among the various traffic elements is more frequent and complex,which affects the normal operation of the traffic system and makes the traffic characteristics change at different levels.Therefore,it is necessary to discuss the mixed traffic flow from the vehicle types,physical characteristics,traffic characteristics,driving environment,driver behavior,etc.Only in this way can the actual traffic flow characteristics be presented more truly,and the establishment of microscopic model for simulation can realize better identification and classification of traffic characteristics,understand the internal interference mechanism of mixed traffic flow,and provide reference for traffic system evaluation and planning.This paper focuses on two typical traffic scenes at road section with mixed traffic flow,and adopts cellular automata idea for modeling and numerical simulation.The main research work can be summarized as follows:(1)The traffic characteristics of road section with mixed traffic flow,motor vehicles and twowheeled non-motor vehicles are analyzed by means of literature,data platform and field investigation.Detailed analysis is mainly made from the aspects of lane width,vehicle physical characteristics,vehicle types,driving behavior,current management standards of non-motor vehicles,and the phenomenon of preempting motorway,which can provide a reference for subsequent modeling work.(2)After the the analysis of the phenomenon of temporary curbside parking of passenger vehicle,a mixed traffic flow model considering this phenomenon is established.Poisson distribution and uniform distribution are adopted for the randomness of the arrival time and place of the passengers;The vehicle type and pacing are represented by the model;Under the improved CCA model,some rules are designed,such as temporary curbside parking,lane changing,preempting motorway and giving way.Through computer numerical simulation,the evolution mechanism of temporary curbside parking,traffic characteristics and the influence of parking time are studied under the opening boundary.The variation characteristics of traffic flow,phase position and space-time in the road section with the phenomenon of temporary curbside parking,which is shown by the result,indicates that the increase of temporary parking time of vehicles can aggravate the decrease traffic capacity and increase the average of extra occupation telescoping with the establishment of fixed temporary stops,it is found that the road capacity can be effectively improved by setting up one temporary stop every 625 m.(3)In order to deeply research the mixed traffic phenomenon in urban road sections with mixed traffic flow,the speed-strictive effect of transverse space is defined and analyzed.Thus,a mixed traffic model based on cellular automata considering this effect is constructed,and this model is numerically simulated and verified by a real example.The influencing factors such as driving space,driving behavior and psychology are integrated in the model,and the capacity of cellular space is sensitive to be changed according to traffic conditions.For the motor vehicle flow,rules such as limited acceleration and active deceleration were introduced.While rules of comfortable driving space,three kinds of lane changing and moving forwarding by expanding are designed.Through numerical simulation under periodic boundary,the characteristics of traffic flow are discussed from basic diagram,lateral spatial variation diagram,spatial and temporal diagram and correlative parameter influence diagram.The model can simulate the density interval in the transition of road initiative;Compared with the traditional model,it can truly reflects the cyclists that willing to pursue a safe and comfortable driving space;The segregation of mixed traffic in motorway,which is dominated by non-motor vehicles.,can be strengthened as the forced lane changing probability of non-motor vehicle decreased and the density increased And then the road congestion will be aggravated;Finally,an real example is given to verify the model,so the model can provide a reference for the modeling of mixed traffic flow considering the influence of multiple factors. |
