Exploring The Impacts Of Urban Expressway Toll Lane On Road Segment Capacity

This paper proposes a traffic management model in which the urban toll lane will be set up on the urban expressway in order to alleviate traffic congestion and improve passing efficiency, especially to meet different requirements of travel time. The urban toll lane is a separate lane set on the urban expressway which is free for public transport vehicles but needs payment from private cars. Public transport vehicles include all the vehicles which can provide public services, like city bus, coach bus, company shuttle bus, ambulance and other emergency vehicles. The separate toll lane can not only ensure bus priority but can also adjust the rate of charge according to the degree of traffic congestion to control the private traffic flow. To some extent, as an efficient way of traffic management, the urban toll lane has both advantages of charge for congestion and bus priority. At the same time, it can avoid slack in utilization of bus lane and the matter of fairness caused by charging congestion fee.Based on the national key basic research program of China 973 ?Project No.: 2012CB725402? and the graduate student innovation projects of Jiangsu Province?Project No.:CXZZ13₀121?, this paper has implemented a research to explore how urban toll lane of expressway exerts influence on the road section capacity through analyzing the real traffic flow data from mechanistic, theoretical and case-applied aspect. In this paper, a new traffic flow data collection method has been designed at the beginning. And then, we construct the car-following model and lane-changing model which can apply to the characteristics of mixed traffic flow after studying the property of urban expressway in our country. In this section, the influence of toll lane on expressway traffic flow is theoretically discussed on the basis of fundamental diagrams of traffic flow models. Build upon this, a simulation system of expressway traffic flow, combined with the cellular automaton model, are established to study the changing mechanism of expressway capacity. At last, a certain expressway is selected to study the actual influence of toll lane on road section capacity. The main content of the whole study can be explained as follows:At first, comparing to the adaptability of existing mainstream traffic flow data, a combination of roadside laser and microwave radar detector was appropriately chosen as the data collection method of expressway traffic flow. We subsequently determined when and where to carry out the traffic flow data collection according to the set up requirements of different detectors. And then the obtained data was cleaned by its own characteristics due to vehicle classification, flow fluctuation and speed fluctuation. The research data was discussed from the aspects of distribution differences of traffic flow, speed and density on lanes in order to constructing a traffic flow model applied to the expressway transit rule in our country. Furthermore, choice preference of drivers on lanes,capacity wastage and so on were taken into consideration as well.Second, compared to the existing research results of car-following model, we found car-following behaviors of different vehicles, restricted conditions of vehicle's acceleration and deceleration and time headway of different car-following behaviors play a great role in building the exclusive car-following model applied to the characteristic of expressway in our country. Therefore, the least square estimator in nonlinear regression model was selected to analyze the obtained car-following data of expressway to fit the parameters of car-following model we proposed in the paper. What's more, the model we proposed was also used to contrast Edie car-following model and Gazis process model respectively.Third, a new lane-changing model of expressway was established on the basis of utility function model through analyzing the characteristics of lanes changing on the expressway. The explaining variables of different utility functions in this model can be used to discuss the lanes changing preference of drivers when they are in the face of dynamic and complicated traffic flow. Then, according to the actual survey data, the lane-changing model was calibrated by the maximum likelihood equation. With the help of Receiver Operating Characteristic Curve, our model was contrasted with Choudury Model on the aspect of the efficiency of lane-changing behaviors.Fourth, the influence of mixed traffic flow on road section capacity is theoretically discussed on the basis of fundamental diagrams of traffic flow models. With the reference of Shifting Bottleneck Theory, the characteristics of toll lane traffic flow and their impacts on the traffic flow of the other lanes were completely analyzed to determine the traffic operating conditions of toll lane. Furthermore, how toll lane improves traffic capacity of expressway has been studied in theory as well.Fifth, on the basis of cellular automata model, combined with the car-following model and lane-changing model proposed in this paper, a complete simulation system of urban expressway traffic flow was constructed. And the system can not only contribute to discuss the microscopic varying patterns of expressway traffic flow, but can also describe the macroscopic properties of actual traffic flow.At last, on the basis of the simulation system proposed previously, we take Longpan Road for example to study the changing rules of road section capacity before and after setting toll lane.As a new traffic management and control technology, toll lane has already achieved success in many engineering projects. A large amount of research achievements have also been made in the academic community, but Chinese researches and practical engineering application are relatively less. As the supplements and perfect of national mixed traffic flow study, the research results in this paper help to quantitatively analyze the influence of toll lane on road section capacity, and understand the increase of expressway's utilization made by toll lane. In addition to this, our research will provide the theoretic support for setting toll lane and be beneficial to encourage innovation in reducing urban traffic congestion.