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Journal ArticleDOI

Integrating people and place: A density-based measure for assessing accessibility to opportunities

28 Jul 2014-Journal of Transport and Land Use (Journal of Transport and Land Use)-Vol. 7, Iss: 2, pp 23-40

TL;DR: The goal here is to understand the magnitude and nature of the opportunities a mobile object had access to, given known location points and a time budget for its movement.

AbstractMobile object analysis is a well-studied area of transportation and geographic information science (GIScience). Mobile objects may include people, animals, or vehicles. Time geography remains a key theoretical framework for understanding mobile objects' movement possibilities. Recent efforts have sought to develop probabilistic methods of time geography by exploring questions of data uncertainty, spatial representation, and other limitations of classical approaches. Along these lines, work has blended time geography and kernel density estimation in order to delineate the probable locations of mobile objects in both continuous and discrete network space. This suite of techniques is known as time geographic density estimation (TGDE). The present paper explores a new direction for TGDE, namely the creation of a density-based accessibility measure for assessing mobile objects' potential for interacting with opportunity locations. As accessibility measures have also garnered widespread attention in the literature, the goal here is to understand the magnitude and nature of the opportunities a mobile object had access to, given known location points and a time budget for its movement. New accessibility measures are formulated and demonstrated with synthetic trip diary data. The implications of the new measures are discussed in the context of people-based vs. placed-based accessibility analyses.

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Citations
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Journal ArticleDOI
TL;DR: Results show that individual and place-based differences in food accessibility may be delineated with the metrics, and possible ‘deserts’ or areas of inaccessibility may be identified through a bottom-up analysis of the travel and mobility experience of a representative sample of individuals.
Abstract: Within the geography, transportation, and public health communities there has been intense interest in better understanding the linkages between health outcomes such as obesity rates and people's access to healthy foods. In this nexus, personal access to healthy food is shaped by a number of individual and geographical factors including people's time available for shopping, the quality of proximal food vendors (e.g. supermarkets vs. convenience stores), and the nature of the transportation systems available to facilitate mobility. Building on recent research in disaggregate accessibility modeling, including that of time geography, this paper describes an individual-level modeling approach for quantifying peoples' food environments. The approach works by measuring the accessibility people have to local food shopping opportunities given their activity patterns and available time budgets. Individuals' food accessibility may be compared to one another and the underlying mobility afforded by the transportation system is accounted for. Moreover, the individual-level measure is such that it may be resolved to places, whereby the aggregation and mapping of multiple individuals' food accessibility experiences is possible. Hence, possible ‘deserts’ or areas of inaccessibility may be identified through a bottom-up analysis of the travel and mobility experience of a representative sample of individuals. These ideas are demonstrated with spatial data from a smaller urban area in Florida. Results show that individual and place-based differences in food accessibility may be delineated with the metrics.

57 citations


Journal ArticleDOI
Abstract: Accessibility is facilitated by well-organized transportation systems that move people efficiently, and it is improved as more activities are reachable to people given the means of available travel. As the current population ages, it will ultimately challenge those who manage transportation systems in their attempts to satisfy the older population’s basic needs. Scanning the literature, accessibility has not been fully explored in relation to aging and older populations. We construct a systematic quantitative analysis of the older population’s accessibility to potential activities. Given their residential patterns and the prevailing transportation system, we ask whether they have as much potential accessibility to activities as their younger counterparts. Our study area is a smaller metropolitan area in the state of Florida. Using highly disaggregate spatial data containing the locations of populations and possible activities, we implement accessibility models in a Geographic Information Systems (GIS) environment, accounting for mode of transportation. Scenarios and activities analyzed are informed by a review of the broader literature as well as our own analysis of the 2009 National Household Travel Survey. We find that the potential accessibility of the aging population varies by activity type and differs with other age group cohorts. When we look in detail at subgroups within the aging population, the oldest group (those 85+) tends to have higher levels of accessibility.

49 citations


Journal ArticleDOI
Abstract: Improving job accessibility can increase the probability for individual persons to be employed and reduce their commutes. Empirical research suggests that the relationship between job accessibility and employment outcomes differ across income groups, but no research has investigated the difference or explored which income groups benefit the most from job accessibility improvements. This research fills the gap by examining six income groups in the Los Angeles metropolitan area. Results show that job accessibility affects the employment status of medium-to-low income groups (household income between US$25,000 and US$75,000). For the lowest-income group (household income lower than US$25,000), owning a car significantly improves their chances to be employed, but job accessibility has no effect. On the other hand, higher job accessibility is associated with shorter commuting distance for the other five income groups, but not for the lowest-income group. These results suggest that transportation and land use policies need to address the specific needs of distinct population groups and underscore the importance of spatial access for the middle-class, which tends to be overlooked in the literature on transportation equity.

40 citations


Journal ArticleDOI
TL;DR: The results of the case study show that the proposed location-based space-time accessibility measures can well capture the temporal variation of accessibility, due to the dynamics both of traffic conditions and of individuals' intensities in performing activities at different times of day.
Abstract: Conventional location-based accessibility measures are static and cannot represent accessibility fluctuations at different times of day. To fill this gap, this study proposes location-based space-time accessibility measures to capture the temporal variation of location-based accessibility. Using the space-time utility perspective, the accessibility of a location is conceptualized as the space-time utility offered by a set of facilities accessible from the location. Individuals' facility choice behaviors among multiple alternatives are explicitly considered. A time-dependent facility attractiveness function is introduced to represent the temporal variation of individuals' needs to perform activities at a certain facility. The introduced function is formulated as two components: a time-invariant component representing individual satisfactions derived from activity participation at the facility, and a time-varying component expressing individuals' dynamic intensities to perform a certain type of activities at different times of day. To demonstrate the applicability of these proposed measures, a comprehensive case study has been carried out in Wuhan, China. The results of the case study show that the proposed measures can well capture the temporal variation of accessibility, due to the dynamics both of traffic conditions and of individuals' intensities in performing activities at different times of day. The proposed measures require moderate level of data, in terms of rich facility information; and most of these data could be extracted from social media applications.

26 citations


Journal ArticleDOI
Abstract: As accessibility becomes an increasingly relevant concept in the analysis of sustainable transport and urban development, the accuracy of accessibility measures becomes increasingly vital. While more complex measures are gradually gaining popularity with increasing data and computational resources, policy makers and planners are still prone to opt for less complex methods that are easy to use and interpret. The cumulative opportunities measure is the most widely applied accessibility measure in planning practice, but it is also among the least accurate due to its lack of consideration of the impact of competition for those opportunities. This study seeks to highlight the impact of addressing competition for different urban services in the cumulative opportunities measure. A competition component is added to the measure, which is applied to a case study of three types of urban services in the Perth metropolitan area; jobs, primary/secondary education and shopping. The results show that considering competition changes the spatial patterns of accessibility and its equity. Since this approach reveals demand-supply imbalances, it can more accurately determine spatial inequalities in accessibility, and hence increases the utility of the cumulative opportunities measure. We also find that the three services had varying levels and spatial patterns of accessibility and spatial equity, thus relying on any single one of them for assessing spatial structural performance can be misleading.

23 citations


References
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4,813 citations


"Integrating people and place: A den..." refers background in this paper

  • ...Note that this does not express the raw probability of finding the object at a location; rather it provides a relative measure of that likelihood, which that can be directly compared across all locations in the map (Silverman 1986)....

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Journal ArticleDOI
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Journal ArticleDOI
Abstract: An empirical examination of the residential development patterns illustrates that accessibility and the availability of vacant developable land can be used as the basis of a residential land use model. The author presents an operational definition and suggests a method for determining accessibility patterns within metropolitan areas. This is a process of distributing forecasted metropolitan population to small areas within the metropolitan region. Although the model presented is not yet sufficiently well refined for estimating purposes, the concept and the approach may be potentially useful tools for metropolitan planning purposes.

2,529 citations


"Integrating people and place: A den..." refers background in this paper

  • ...…approaches (Levine et al. 2012; Neutens, Schwanen, and Witlox 2011; Li et al. 2011; Harris 2001; Miller 1999; Burns 1979; Weibull 1976; Ingram 1971; Hansen 1959; Shen 1998)While precise definitions vary across disciplines and analytical contexts, generally accessibility is thought to mean the ease…...

    [...]

  • ...Accessibility-related research has thrived during the last few decades, with new data and computational tools facilitating innovations rooted in classical approaches (Levine et al. 2012; Neutens, Schwanen, and Witlox 2011; Li et al. 2011; Harris 2001; Miller 1999; Burns 1979; Weibull 1976; Ingram 1971; Hansen 1959; Shen 1998)While precise definitions vary across disciplines and analytical contexts, generally accessibility is thought to mean the ease with which activities can be reached in space....

    [...]


Journal ArticleDOI
Abstract: Accessibility is an important characteristic of metropolitan areas and is often reflected in transportation and land-use planning goals. But the concept of accessibility has rarely been translated into performance measures by which policies are evaluated, despite a substantial literature on the concept. This paper is an attempt to bridge the gap between the academic literature and the practical application of such measures and provide a framework for the development of accessibility measures. Issues that planners must address in developing an accessibility measure are outlined, and two case studies suggestive of the range of possible approaches are presented.

1,269 citations