Analyzing Spatial Organization of Tehran Metropolitan Area Using ‎Demographic Flow

In general, not only urban systems are limited to physical structure and spatial deployment of urban settlements, but also they include flows, communications and interactions between cities in such systems. In this spatial flow, each individual node will have different situation and character based on its degree, type, composition, and its potential of relation with other nodes. In other words, the situation of each city in the hierarchy of urban network and its role in the network is influenced by its own spatial and functional organization/arrangement in flow space. Therefore, urban areas will be known as “the network” over time. The essence/nature of the network depends on complexity of relations between cities, dynamic nature of the network and cohesion and dependency of areas. According to studies based on the Tehran Metropolitan Regional Plan and other documents, in spite of existence of decentralization policies in Tehran in recent decades, this city still remains dominant to the surrounding urban areas. Besides, centralized forces toward Tehran with a large number of people and human resources that aims to use better services and facilities concentrated in Tehran will be associated with centralized and unbalanced spatial organization. On the other hand, considering numerous economic, social, environmental and structural– spatial problems, unbalanced development in regional territory, and being the capital city of the country, it is necessary to define a system which provides spatial-functional coherence and integrated and balanced spatial development in the region. The study aims to evaluate the spatial interactions among the cities located inside the Tehran metropolitan region by using the data of trip flows and making some measurements to evaluate spatial structure of that region. In this study, Relational Methods and particularly, methods based on Social Network Analysis and Graph theory are used to analyze the people movements. Origin-Destination trip data was collected by documentary method and were applied to make some measurements for network analysis. The trip flows is calculated based on the number of passengers (traveling by cars, buses or minibuses) and their origin and destination through cities located in Tehran metropolitan region. The goal of this study is to examine and analyze spatial structure of Tehran metropolitan region in the form of a regional network that consists of cities and the connections among them and to determine the range of functional impact of each city in relation to others. Regarding to the result of regional network analysis using the information of trip flows occurred among the cities during the study period (1996 to 2011), We still see the high concentration of activities in the city of Tehran and obvious dominance of this city over the region. However, there are obvious signs that the intensity of concentration and domination of Tehran is gradually decreasing and the surrounding cities in the region are gaining more functional power. Therefore, the spatial structure of the region is gradually changing from a completely mono-centric structure to the formation of a multi-centric structure. This indicates the tendency for empowering the secondary centers and having more balanced patterns in distribution of activities across the region.