Experimental Investigation On Pedestrian-Bicycle Mixed Merging Flow In T-Junction

To implement the country’s long-term strategy to achieve carbon neutrality and build a green and harmonious society,the Ministry of Transport has proposed a "Green,Circular and Low Carbon Transportation Development Guide".Walking and bicycling are the ideal means of transportation for short-distance travel because of their flexibility and punctuality.And with the popularity of "bike-sharing",the number of bicycles on urban roads has increased dramatically,making walking and bicycling an important part of integrated urban transportation.Although the government has proposed to protect the basic right-of-way of walking and bicycling,the current planning and design of traffic roads and the arrangement of slow lane facilities are not perfect yet,and pedestrians and bicycles often mix when the roads are narrow or congested,which makes the phenomenon of pedestrians and bicycles mixing on the streets more and more common.T-junction,where the traffic flow merges from two branches into one,is a common traffic infrastructure.The flow efficiency could reduce dramatically at the merging intersection of the T-junction,resulting in lower efficiency of mixed pedestrian-bicycle flow and easily causing congestion.To improve traffic efficiency,it is necessary to analyze the flow characteristics of mixed pedestrian-bicycle flow at the merging area.In this paper,a controllable experiment was carried out to study the influence of the change in the total number and proportion of pedestrian-bicycle,as well as their coupling.When analyzing the influence of the changing total number,the proportion of pedestriansbicycles was fixed at 1:1,and the total number increased from 0 to 60 with a gradient of 12.When analyzing the influence brought by the changing proportion,the total number of pedestrians-bicycles was fixed at 60,and the proportion of bicycles increased from 0% to 100%with a gradient of 17%.When the coupling effects of total number and proportion are considered comprehensively,there are three ratios of pedestrians and bicycles: 1:0,1:1,and0:1 under the conditions of low density,medium density,and high density.At the same time,the experiment also set up two kinds of merging modes: symmetric merging and asymmetric merging to analyze the change of motion characteristics in different directions of merging flow.When studying the influence on the change of the total number of pedestrian-bicycle merging flow,we mainly analyzed the global travel time and found that the travel time increases linearly with the increase of the total number as well as the increase of the proportion of bicycles.Under the condition of asymmetric merging,the travel time is shorter than that of symmetric merging.In the analysis of local flow characteristics,we found that the speed of pedestrians and bicycles in each group is higher after merging than before merging.The congestion phase occurs when the total number of pedestrians reaches 60 under the condition of symmetrical merging.Under the condition of asymmetric merging,the congestion phase appeared at 36.When studying the influence on the change of the proportion of pedestrian-bicycle merging flow,we found that the proportion of bicycles reaches 50% under the condition of symmetrical merging,the channel starts to be congested,and as the proportion of bicycles continues to increase,the channel is congested.Under the condition of asymmetric merging,when the proportion of bicycles reaches 50%,the channel is congested.In the study of the coupling effect of the total number and proportion of pedestrianbicycle,it is found that the channel will not be congested when the proportion of bicycles is very small at low,medium,and high density.When the proportion of bicycles reaches 50%,the channel congestion will occur in the high-density state.When the proportion of bicycles reaches 100%,congestion occurs in both medium and high-density states.The research results of this paper can provide theoretical guidance for the analysis method and index determination of pedestrian-bicycle merging flow,provide a technical theoretical basis for traffic planning and management and road junction facility design,and also provide data reference for the safety assessment of T-junction.