Gradient Mechanism Analysis Of Urban Rail Transit Network Scale And Model Study

With the rapid socio-economic development of cities, the urbanization process accelerates quickly, causing the issues such as traffic demand increasing, the residents increasing the average trip distance constantly. The number of cars increased to a range has brought tremendous pressure to road construction, traffic management, as well as the environment; the road network capacity has been unable to meet the growing demand for urban transport. Urban rapid transit which has special technical advantages such as quickly, timely, safety, cleanly, environmentally become the first choice of many large and medium-sized cities to solve the traffic problems. However, Urban rapid transit, being one of the most significant infrastructures in the city, is a systematic engineering with broad effect, deep comprehension, and huge invest, so the pre-planning of urban transit projects should be given highly admiration. Meanwhile, the network scale goes through the whole jobs of network planning, so it is very important to give research on the network scale.Starting with the meaning of urban rail transit network scale, the paper mainly studies network density and stations spacing. Based on the gradient effect of network density gradually reduced and stations spacing increased from the city center to suburbs, it analyses the mechanism of gradient. From analyzing the urban rail transit network scale factors (qualitative analysis), taking Chengdu city as an example to process quantitative analysis by means of factor analysis (selecting variable parameters——getting public factor by the way of factor analysis——structuring determine function and calculating to prove the existence of gradient effect). To learn more about regional network density grade, cluster analysis is made to grade the regional network density. Using the same way to analyze the regional stations spacing scale, by selecting variable parameters and structuring determine function to prove the existence of gradient effect, we also can obtain the stations spacing grades by using the cluster analysis.Based on attraction geometric analysis, which means line spacing projects network density, the attraction of transit station being abstracted as a circle by the radius of R, while the city center and suburbs being simplified into regular graphics, a network density model is established. Combined with the front research of network density grading, different R by different region levels is determined here. According to the traffic balance between supply and demand principle, network density of different regions are developed. Since the model is based on the attraction of station, it can determine stations spacing scale.In this paper, qualitative analysis provided is helpful to study the rail transit planning program on the basis of the grade of network density and stations spacing scale, network density and stations spacing model established provide quantitative analysis, thus the paper is able to provide a guide to urban rail transit network planning study.