The Capacity Analysis Of Modern Streetcar Intersection

With the increasing diversification of public transportation modes, modern streetcar has been introduced into many cities because of its advantages in capacity, environment and landscape and has been acknowledged with great significance in aspect of building transit metropolis. However, to assure the operation effectiveness, it is necessary to provide independent right of way for modern streetcar, generating more requirement for time and space resource. Additionally, the characteristic of vehicle type aggravates the consumption of the resource. Corresponding phenomenon are more obvious at intersection. Therefore it is imminent to develop quantitative measures addition to building the computational modal for modern streetcar intersection, based on which design schemes and control methods should be put up to improve traffic capacity at intersections so as to enhance effectiveness. And it will make up for the deficiency in quantitative research of modern streetcar, beneficial for the development of multi-modal and multi-level of urban public transport system. It is a prospective and challenging research topic.At first it summarizes related theoretical results domestically and internationally. To make up the shortfalls in influence factors and models with respect to capacity of modern streetcar intersection, this paper gives out the research content and goals according to characteristics of streetcar intersection by analyzing existing theories and practices. Then it analyzes the technical characteristics of vehicles and operation and organizations aspects. Through the comparison between modern streetcar and other transit modes, it presents the difference of modern streetcar in vehicle capacity, speed and economic cost. And it analyzes traffic capacity at intersection under the influences of non-motorized traffic, intersection rebuilding, modern streetcar system, departure frequency and signal timing and control.Based on stopping line method, it builds traffic capacity modal for modern streetcar intersection and builds corresponding models for different signal control strategies in the light of streetcar trajectory. The principle model parameter is time headway which is achieved through traffic survey. In the survey schemes, data are collected at intersection of Nanjingzhong Road and Aoti Street and intersection of Jiangdongzhong Road and Hexi Street where streetcar travel through. Depending on movement and whether traversing tracks, time headway values which refer to time interval between two consecutive vehicles that pass through stopping line (not traversing tracks) or the first track (traversing tracks), are obtained. Finally the modal parameter—average time headways are obtained for different direction when traveling through tracks or not. And the results show that the time headway values are higher when travelling through tracks compared.It analyzes and summaries a process for capacity calculation based on traffic capacity models built here. The intersection of Jinshan Road and Zhujiang Road in Suzhou streetcar line 1 is chosen to conduct case study. Firstly, by substituting cycle length, phase green time and average headway for each movement into formula, the capacity of each lane can be calculated as well as phase capacity and capacity of intersection under fixed-time signal control. Then capacity for partial priority and full priority intersection are calculated similarly. The results show that:capacity under fixed-time signal control scheme is 4420pcu/h; by comparison, the capacity decreases to 3080pcu/h for partial priority signal control; the capacity is just 1764pcu/h for full priority signal control. The full priority control strategy is appropriate for intersections where traffic demand is low and streetcar should maintain high level of service. Under the circumstances of higher traffic capacity and streetcar priority, partial priority signal control should be preferred.