Evaluation Research On Interchange Renovation

Renovated interchange refers to this type of interchange: they need renovation because of the traffic capacity of existing interchange can not meet the traffic demand,the transformation of road network or any other reasons.This dissertation first analyzes the reasons for interchange renovation. These reasons include the saturation of the traffic capacity, road network transformation factors, interchange dysfunction and the low criterion of its design. The saturation of the traffic capacity of these interchanges could lead to serious traffic congestion, so it comes up with one question: whether or not the interchange needs to be renovated? Therefore, it is necessary to make scientific assessments of the status of the interchange and provide basis for decision-making.This paper introduces the evaluation method of service level of the interchange which based on the traffic capacity theory and points out the inadequacy of this evaluation method: (1) Every part of the interchange (the main line, the ramp and intertwined areas, etc.) has its own evaluation indicator, there is no indicator which could make overall evaluation. (2) Specific to objects of this study, the existing service level evaluation method could not reflect the severity of traffic congestion, so it can not provide a scientific basis for decision making. (3) The service level evaluation method essentially evaluates the hardware of the transportation facilitie itself rather than the quality of service accepted by users.This paper established evaluation system of the interchange status based on the average vehicle delay. Compared with the service level evaluation method, the evaluation system of the interchange status has several advantages: (1) Based on average delay time of vehicles driving through the interchange area, the integral and every part of interchange (the main line, the ramp, intertwined areas, etc.) has single uniform evaluation indicator. (2) The evaluation system of the interchange status can quantitatively describe the average delay time in every routes (ramp) and directly reflect the severity of traffic congestion. (3) Based on average delay time, the evaluation system of the interchange status could directly reflect the service quality of transportation facilities accepted by users, so it embodies the "people-oriented" principle. This paper briefly introduces the microscopic traffic flow simulation system VISSIM. Then, it made evaluation of Chongqing Xinpaifang interchange through the data of average delay time simulated by VISSIM and testified the practicability of this evaluation system.