15,052 research outputs found

    A GIS toolkit to evaluate individual and joint accessibility to urban opportunities

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    Spatial Typology of the Greek Territory Based on Transport Accessibility Indicators:A Cartographical Approach Using G. I. S.

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    Accessing the infrastructure networks, the urban concentrations, the commercial and other activities or key locations, is considered by the spatial planners as a significant and sensitive variable for the territorial analysis. The spatial policies are determined today by the principals of equal and balanced distribution of human resources and activities, as well as by the systematic study of territorial disparities in the deepest territorial analysis detail level possible. The traditional calculative methods of accessibility indicators, does not take into account the entire space of the study area. In the contrary, it’s mainly based on calculating the travel cost on linear networks using the "arc-node" topologies. According to these methodologies, the variables (time, distance, or other types of cost) are calculated only for the network elements (nodes, lines). During the recent years, some published studies have appointed the above issue. Accessibility is faced as continuous data thus it is valued and attributed in the entire area of study and not just on the network body. This study’s main objective is to generate an accumulative travel cost indicator for the Greek territory, using all major transportation means. In addition the respective spatial typology will be created. The indicator is produced using three distinctive spatial levels representing the three transportation means (land, sea and air transportation). The study’s methodology is based on the formation of continuous cost surface model, in raster format, using all the aforementioned transportation nodes. The travel cost value that each cell on the surface will be assigned to, is the absolute time of traveling towards the transportation nodes or towards specific linear network elements. An emphasis is given to the study’s cartographic component as well as to the comprehensive use of spatial analysis techniques which are available on GIS software.

    Network geography: relations, interactions, scaling and spatial processes in GIS

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    This chapter argues that the representational basis of GIS largely avoidseven the most rudimentary distortions of Euclidean space as reflected, forexample, in the notion of the network. Processes acting on networks whichinvolve both short and longer term dynamics are often absent from GIscience. However a sea change is taking place in the way we view thegeography of natural and man-made systems. This is emphasising theirdynamics and the way they evolve from the bottom up, with networks anessential constituent of this decentralized paradigm. Here we will sketchthese developments, showing how ideas about graphs in terms of the waythey evolve as connected, self-organised structures reflected in theirscaling, are generating new and important views of geographical space.We argue that GI science must respond to such developments and needs tofind new forms of representation which enable both theory andapplications through software to be extended to embrace this new scienceof networks

    Concepts, reflections and applications of social equity: approaches to accessibility to primary goods and services in the region of Flanders, Belgium

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    Mobility presents a variety of opportunities as it allows users to access locations and services, and to meet people beyond their immediate surroundings. While the concept of mobility primarily focuses on the ease of moving, accessibility delineates the actual potential to participate in out-of-home activities. As a result, accessibility is a complex concept with a multitude of foci. This complexity is presented in the first section, which explains the general concept of accessibility, how it is defined and how it is related to the notion of transport-related exclusion. This section also gives an overview of the body of literature on the measures to determine area-based as well as personal accessibility levels and points out the important contrast between the simple, easy-to-interpret methods, adopted by policy makers and the complex methods preferred by experts. The second section clarifies how the dichotomous relationship between the urban and rural environment is reflected in transport policy that emphasizes on (especially car-based) mobility rather than on accessibility. Furthermore, the environmental and economic points of view are highlighted and the common policy strategies focused on sustainability are illustrated. Subsequently, the shortcomings in the way in which the contemporary debates concerning mobility, sustainability and the social implications of transport planning are conducted, are criticized. Finally, the last part of this section is dedicated to an extensive discussion on the ability of transport policies to, on the one hand, generate spatially as well as temporally uneven accessibility effects that give preference to certain population groups above others, and on the other hand, their ability to strive for a more equitable distribution of transport services amongst the population. The third section proposes two methodologies for measuring transport-related social exclusion implemented in a literature-based case study in Flanders. These studies comprise the following topics: measuring transport gaps by relating the social to the transport disadvantage and measuring modal disparities by comparing accessibility by private and public transport. The former investigates in which areas the provision of the public transport system is not tailored to specific public transport needs. The latter examines the disparity in access by private and public transport in order to highlight the car dependency. Both case studies incorporate the temporal variability in provision through the private and public transport network, as the time-of-day strongly influences accessibility levels

    Modelling potential movement in constrained travel environments using rough space-time prisms

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    The widespread adoption of location-aware technologies (LATs) has afforded analysts new opportunities for efficiently collecting trajectory data of moving individuals. These technologies enable measuring trajectories as a finite sample set of time-stamped locations. The uncertainty related to both finite sampling and measurement errors makes it often difficult to reconstruct and represent a trajectory followed by an individual in space-time. Time geography offers an interesting framework to deal with the potential path of an individual in between two sample locations. Although this potential path may be easily delineated for travels along networks, this will be less straightforward for more nonnetwork-constrained environments. Current models, however, have mostly concentrated on network environments on the one hand and do not account for the spatiotemporal uncertainties of input data on the other hand. This article simultaneously addresses both issues by developing a novel methodology to capture potential movement between uncertain space-time points in obstacle-constrained travel environments

    A Methodology to Evaluate Accessibility to Bus Stops as a Contribution to Improve Sustainability in Urban Mobility

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    Walking and transit are the backbone of sustainable mobility. Bus stops not only represent the connection between the two, but are also central in dictating the attractiveness of the latter. Accessibility of bus stops becomes, then, pivotal in increasing both attractiveness and sustainability of public transport. The paper describes a multi-step methodology to evaluate bus stops’ accessibility starting from a cluster of seven indicators describing objective and subjective features influencing passengers’ choice toward a given bus stop. The indicators are weighed by a questionnaire submitted to experts. Finally, a multicriteria analysis is developed to obtain a final score describing univocally the accessibility of each stop. Outcomes are mapped and a case study in Rome is reported as an example, with 231 bus and tram stops assessed accordingly. Results shows the relevance of the urban network and environment in evaluating the accessibility and in promoting more sustainable mobility patterns. Research innovation relies on the possibility to merge data from different fields into a specific GIS map and easily highlight for each bus stop the relationships between built environment, passengers’ comfort, and accessibility, with the concluding goal to provide advanced knowledge for further application

    Identifying public transport gaps using time-dependent accessibility levels

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    One of the concerns that has aroused much scholarly attention in transport geography lately is the extent to which public transport provision enables the less privileged population segments, especially those without privately owned motorized vehicles, to participate in activities that are deemed normal within the society they live in. This study contributes to this line of inquiry by proposing a methodology for identifying public transit gaps, a mismatch between the socially driven demand for transit and the supply provided by transit agencies. The methodology draws on the latest accomplishments in the field of modeling time-continuous, schedule-based public transport accessibility. Accessibility levels to key destinations are calculated at regular time intervals, and synoptic metrics of these levels over various peak and off-peak time windows are computed for weekdays and weekends. As a result, a temporally reliable picture of accessibility by public transport is constructed. The obtained index of public transport provision is compared to a public transport needs index based on the spatial distribution of various socio-demographics, in order to highlight spatial mismatches between these two indices. The study area consists of Flanders, which is the northern, Dutch-speaking region of Belgium. The results indicate that mainly suburban areas are characterized by high public transport gaps. Due to the time-variability of public transport frequencies, these gaps differ over time

    Does Accessibility Planning address what matters? A review of current practice and practitioner perspectives

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    'Accessibility' has become commonplace in transport planning and as such there is a plethora of interpretations of what accessibility means, what constitutes a good measure of accessibility, and how this might be applied in practice. This paper presents an overview of approaches to measuring accessibility and presents a case study of Accessibility Planning in England — one approach to formalising the concept of accessibility. Results of semi-structured interviews with local authority officers are discussed to establish whether current approaches, allow their desired outcomes to be met. This approach demonstrates where there might be gaps between measured or modelled accessibility and the perceptions of the individuals. Findings suggest that while the process is deemed useful in raising the profile of accessibility issues, measures of accessibility do not necessarily easily translate into quantifying benefits of those improvements that are perceived by practitioners to improve accessibility and reduce transport disadvantage

    Study on behavioral impedance for route planning techniques from the pedestrian's perspective: Part I - Theoretical contextualization and taxonomy

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    The interest of researchers for analyzing of best routes and shortest paths allows a continuous technological advance in topological analysis techniques used in the geographic information systems for transportation. One of the topological analysis techniques is the route planning, in which the constraint management must be considered. There have been few studies where the constraint domain for pedestrian in an urban transportation system was clearly stated. Consequently, more studies need to be carried out. The aim of this paper is to provide a theoretical contextualization on identification and management of constraints to ascertain the behavioral impedance domain from the pedestrian perspective. In this part of the research the grounded theory was the research method used to develop the proposed theory. A meta-model was used to (1) define the behavioral domain structure, (2) hold the behavioral data collection and (3) verify the design of the proposed taxonomic tree. The main contribution of this article is the behavioral domain taxonomy from the pedestrian perspective, which will be used to implement a module responsible for the constraint management of an experimental application, named Router. Within this context, the proposed taxonomy could be used to model cost functions more precisely.Postprint (published version

    New technologies for urban designers: the VENUE project

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    In this report, we first outline the basic idea of VENUE. This involves developing digital tools froma foundation of geographic information systems (GIS) software which we then apply to urbandesign, a subject area and profession which has little tradition in using such tools. Our project wasto develop two types of tool, namely functional analysis based on embedding models of movementin local environments into GIS based on ideas from the field of space syntax; and secondlyfashioning these ideas in a wider digital context in which the entire range of GIS technologies werebrought to bear at the local scale. By local scale, we mean the representation of urban environmentsfrom about 1: 500 to around 1: 2500
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