Assessing the impact of accessibility on spatial variation of land values for different land use distributions : a case study of Bhopal city

Abstract

The thesis evaluates accessibility by computing centrality measures of the street network and examines the applicability of accessibility values in describing the movement pattern, land use distribution and land values variation for the Bhopal city, India. As spatial planners, we define and control the urban form, but our plans fail to take into consideration the impacts of urban form on the individuals. The thought of this thesis initiated from a question “can urban form affect movement pattern and distribution of functions within an urban spatial structure, if affirmative, then in what manner?”. From generations, various conceptual and empirical studies have attempted to quantify, model and formulate how the built environment is valued by people. Studies lack to quantify urban morphology probably due to lack of precise methods and techniques. Urban morphology entails five systems viz., natural system, street system, urban tissue, building system and plot system. Street system defines the shape of the urban structure and is associated with spatial accessibility. Streets act as channels to access places and hence, individuals decide on and select streets in order to reach their destination, thereby involving human cognition which guides the overall movement. In turn, accessibility is associated with attractiveness of the place, more accessible the place is more is its attracting potential, hence determine the functional use and market potential of the place. Therefore, the focus of this thesis is what information can be extracted from the street network which can explicate the arrangement of spaces, functional use, density and pattern of movement within the urban spatial structure. Land use planning has traditionally focused on design, physical measures and narrowly defined environmental effects, the decision that planners make, have an economic impact as well, which is generally not taken into account while formulating planning proposals resulting in land-use deviations, non-effective performance of land use with respect to transportation and etcetera. Witnessing the problem of sprawl, ribbon development and associated issues for example escalating trip lengths, pollution levels in Indian cities there is need to integrate

land use and transportation in order to develop robust, dynamic and efficient cities. There is lack of methodology which can provide a distinct picture of interaction amongst the systems and dynamics in an urban structure which may be helpful in preparing development plans and mobility plans. Therefore, there is need of methodology which considers the transportation system, economic aspects and functional dimension of space, which further, may be employed for land use zoning. In order to achieve the stated aim, the study was divided in to certain parts, purpose or milestone of each part may be regarded as an objective, which are encapsulate below: 1. To identify suitable method and calculate accessibility value associated with each segment of the selected city. Also, compute a ward level accessibility index for the sub-area selection within selected city. 2. To observe and analyse vehicular movement pattern in the identified subarea and determine its relationship with accessibility values. 3. To observe and analyse land use distribution and land value pattern with respect to computed accessibility indices and also, establish relationship between land value and accessibility values and to suggest the application of the obtained relationship in urban planning. The formulation of objectives was followed by the review of various literary works to understand concepts and notions related to urban form, land use dynamics, land valuation, accessibility, space syntax theory, graph theory and methods for measuring accessibility using network measures. The dataset required and method selection for calculation of centrality indices was the outcome of the literature review. The data sets were then compiled from both primary and secondary sources in order to accomplish the objectives. The quantitative method of analysis include multiple centrality assessment (MCA) for the calculation of network centrality indices. Other analysis and calculations include statistical analysis such as correlation, regression and probability analysis. The study involves exhaustive

use of ArcGIS software along with python coding in order to calculate network centrality indices. The multiple centrality assessment involved calculation of two indices that is closeness and betweeness for the entire Bhopal city. The closeness values highlighted the easily accessible areas and betweeness values represented the traffic attraction on the individual street segments. Remarkably, the betweeness values highlighted the major traffic corridors of Bhopal which were then crosschecked from draft comprehensive city mobility plan and development plan of the city. Using ArcGIS software package, ward level accessibility was computed for the entire Bhopal city with the help of computed centrality indices, based on which three wards were selected to carry out objective-2 and objective-3. The primary data of traffic volume and building use was collected and compiled for the selected wards which was then used in analysing the relationship between the accessibility, movement pattern and land use distribution. The circle rates (or collector rates) were marked at both levels city as well as ward level to identify the relationship between centrality measure and land value variation in Bhopal city. The results of composite accessibility index derived from centrality indices highlighted the Central Business District (CBD) as most accessible areas of Bhopal city which includes M.P.Nagar, old Subhash nagar, Old city, New Market etcetera. A high positive correlation was observed between „betweeness‟ centrality index and vehicular traffic volume on the street segments. In case of land use distribution, it was observed that the probability of having a commercial or mixed use increases with increase in betweeness centrality index value and increase in residential use as with gradual decrease in index value. The relationship of closeness index in explaining the two above stated aspects was insignificant. Also, in case of land values the spatial variation of land values at a city level was explained by closeness index and variation at ward level were explained by betweeness index, with correlation coefficient being 0.81 and 0.84 respectively.

The results showed that street network, as an element of urban form was competent in explaining the major aspects of the urban spatial structure. Therefore, in spatial planning, the derived relationship can prove to be useful in following sectors: Using the derived relationship between centrality index and vehicular volume, the traffic volume on street can be estimated and accordingly the width, services and infrastructure may be provided on streets. Land use zoning based on accessibility values to integrate transportation and land use can be helpful for spatial planners to generate a land use scenario. The relationship between land value variation and indices was significant, hence it may be used as an alternative approach in determining the circle rates. The study concludes on the note that network measure of accessibility are powerful indicators in explaining activities within the urban structure. Hence, should be incorporated in the process of preparation of development plan and formulation of development control regulation. The measure can be useful for planners to understand the dynamics of the spatial structure. The methods developed in this research offers promise for transport planning, land use planning applications in Indian context which is urgently called for. The research has contributed to with a robust, dynamic planning tool that will guide spatial planners in justifying their planning decisions in designing policies for urban