Academic journal article Geographical Analysis

Individual Accessibility Revisited: Implications for Geographical Analysis in the Twenty-First Century

Academic journal article Geographical Analysis

Individual Accessibility Revisited: Implications for Geographical Analysis in the Twenty-First Century

Article excerpt

Analytical methods for evaluating accessibility have been based on a spatial logic through which the impedance of distance shapes mobility and urban form through processes of locational and travel decision making. These methods are not suitable for understanding individual experiences because of recent changes in the processes underlying contemporary urbanism and the increasing importance of information and communications technologies (ICTs) in people,s daily lives. In this paper we argue that analysis of individual accessibility can no longer ignore the complexities and opportunities brought forth by these changes. Further, we argue that the effect of distance on the spatial structure of contemporary cities and human spatial behavior has become much more complicated than what has been conceived in conventional urban models and concepts' of accessibility. We suggest that the methods and measures formulated around the mid-twentieth century are becoming increasingly inadequate for grappling with the complex relationships among urban fibrin, mobility, and individual accessibility. We consider some new possibilities for modeling individual accessibility and their implications for geographical analysis in the twenty-first century.

I. INTRODUCTION

Accessibility has traditionally been conceptualized as the proximity of one location (whether zone or point) to other specified locations. Analytical methods for evaluating accessibility have been based on a spatial logic through which the impedance of distance shapes mobility and urban form through processes of locational and travel decision making. As a result, traditional models of urban form and accessibility are based upon a similar conceptual foundation and spatial logic, and the relationships between models of urban form and conceptualizations of accessibility are inextricably intertwined.

Conventional concepts and measures of accessibility are useful for studying a variety of phenomena, especially the aggregate analysis of social groups within an area-based spatial framework. Gravity-based and cumulative-opportunity measures, for example, are helpful for identifying changes in the accessibility of different locations (place accessibility) and the effect of competition on access to urban opportunities (e.g., Shen 1998; van Wee, Hagoort, and Annema 2001; Wachs and Kumagai 1973). Nodal measures are also useful for addressing issues of accessibility within transportation or information networks (e.g., Lee and Lee 1998). These conventional accessibility measures have the general form [A.sub.i] = [SIGMA][W.sub.j]f([d.sub.ij]), where [A.sub.i] is the accessibility at location i, [W.sub.j] is the weight representing the attractiveness of location j, [d.sub.ij] is a measure of physical separation between i and j (in terms of travel time or distance), and f([d.sub.ij] is the impedance function. The most commonly used impedance functions in gravity measures are the inverse power function and the negative exponential function, while an indicator function is used in cumulative-opportunity measures to exclude opportunities beyond a given distance limit. In nodal measures, the impedance function takes the form of an indicator function that reflects the presence or absence of a network link between two nodes.

These conventional measures are, however, less suitable for understanding individual experiences because of recent changes in four broad areas: (a) the processes that shape urban form and contemporary urbanism; (b) the complexities of and individual difference in human spatial behavior; (e) the availability of new technologies, especially GIS, and data for modeling individual accessibility; and (d) the increasing importance of information and communications technologies (ICTs) in people's everyday lives.

In light of these important changes, there is an urgent need to re-examine the concepts and methods in accessibility research, especially in the context of the lived experience of individuals. …

Search by... Author
Show... All Results Primary Sources Peer-reviewed

Oops!

An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.