Primal and Dual Access

Accessibility, measuring the ease of reaching potential destinations, is increasingly being considered as an effective indicator to evaluate the performance of transport and land use interactions. Primal accessibility, a generalization of the first accessibility formulation proposed by Hansen, has been widely used in many studies and demonstrated to be a reliable tool for project, program, and policy evaluation. The dual of accessibility, measuring the time required to reach a given number of opportunities, is less often considered but can be used for optimization in location covering-type problems. This article, hence, clarifies the definitions of primal and dual access, and applies both measures to the Minneapolis—St. Paul metropolitan area for auto and transit to demonstrate their practicality as a metropolitan-level measurement. We explore the correlations and differences between the primal and dual access to better understand the relative strengths of the measures. It is found that, as with primal accessibility, dual accessibility is an efficient approach to evaluate accessibility, which is straightforward to calculate and to explain to policy-makers and the public.     

An Examination of the Stochastic Distribution of Spatial Accessibility to Intensive Care Unit Beds during the COVID-19 Pandemic: A Case Study of the Greater Houston Area of Texas

Sufficient and reliable health care access is necessary for people to be able to maintain good health. Hence, investigating the uncertainty embedded in the temporal changes of inputs would be beneficial for understanding their impact on spatial accessibility. However, previous studies are limited to implementing only the uncertainty of mobility, while health care resource availability is a significant concern during the coronavirus disease (COVID-19) pandemic. Our study examined the stochastic distribution of spatial accessibility under the uncertainties underlying the availability of intensive care unit (ICU) beds and ease of mobility in the Greater Houston area of Texas. Based on the randomized supply and mobility from their historical changes, we employed Monte Carlo simulation to measure ICU bed accessibility with an enhanced two-step floating catchment area (E2SFCA) method. We then conducted hierarchical clustering to classify regions of adequate (sufficient and reliable) accessibility and inadequate (insufficient and unreliable) accessibility. Lastly, we investigated the relationship between the accessibility measures and the case fatality ratio of COVID-19. As result, locations of sufficient access also had reliable accessibility; downtown and outer counties, respectively, had adequate and inadequate accessibility. We also raised the possibility that inadequate health care accessibility may cause higher COVID-19 fatality ratios.     

RURAL–URBAN SPATIAL INTERACTION IN THE GLOBAL SOUTH: LONG‐DISTANCE MOBILITY CHANGES,DESIRES AND RESTRICTIONS OVER TWO DECADES IN RURAL PHILIPPINES

The spatial interaction between rural and urban areas is intense in the Global South. While research into how this interaction influences livelihood opportunities is extensive, longitudinal identification and analysis of rural people's long‐distance mobility is rudimentary. This is problematic given the possible repercussions of a greater flow of people for transport system management (congestion, emissions, investments, social exclusion, etc.). Based on longitudinal survey data from 1990 to 2008/2009, this article addresses this gap by exploring how the long‐distance mobility behaviour of households and individuals has changed over a period of intensified rural–urban interaction in a rural Philippine area. The article furthermore addresses the individuals' mobility desires and restrictions related to long‐distance travel. The results indicate that both accessibility effects and effects related to information and communication technology (ICT), concentration of activities and opportunities towards major cities, age, labour market, and economic situation. Over time, particularly since improved accessibility conditions have enabled much faster travelling, more people have come to travel more frequently (although a suppressed demand is still present and inequalities are considerable) to more distant destinations, major cities in particular, for mainly social motives. A recent countertrend is evident, partly arising from mobile phones replacing physical movement. The increase in private vehicle ownership has so far been slow, so modal choice is still highly sustainable. Overall, the findings support core ideas derived from the new economic geography, but also notes, with earlier studies in transport geography, that travel time is a prime consideration.     

A Measure of Competitive Access to Destinations for Comparing Across Multiple Study Regions

Accessibility is now a common way to measure the benefits provided by transportation–land use systems. Despite its widespread use, few measurement options allow for the comparison of accessibility across multiple urban systems, and most do not adequately control for market competition between demand-side actors and supply-side facilities in localized markets. In this article, we develop a measure of competitive access to destinations that can be used to accurately compare accessibility between regions. This measure stems from spatial interaction modeling and accounts for competition at both the supply and demand sides of analysis, regional differences in transportation networks and travel behavior, and any imbalance between the size of the population and the number of opportunities. We use this method to compute access to employment for Canada's eight largest cities to comparatively examine inequalities in accessibility, both within and between cities, and by travel mode.     

Everyday travel for families with children using wheelchairs: parents’ perceptions of constraints and adaptation strategies

ABSTRACT

There is a norm assuming high mobility in the Western world today, which can increase the social and geographical exclusion of those who have limited possibilities to travel, such as people with disabilities. When it is a child who has the disability, travel-related constraints are likely to affect the whole family’s travel patterns. This study explores travel constraints among Swedish families with children with cerebral palsy who use wheelchairs. A time-geographical framework is employed. Interviews with parents show that these families’ everyday mobility is affected by authority, capacity and coupling constraints, and that it is often a combination of these constraints that makes travelling difficult. The families use different strategies to negotiate these constraints. In addition to strategies controlled by the families, the findings suggest that there is also a need for governmental support and a barrier-free transport system to enhance their mobility.     

Universal Access for Universal Value: Creating Disabled Access at Heritage Sites for those with Mobility Impairments

Abstract

In today's society it is recognized that all people, regardless of disability, should be welcomed at heritage sites. As mobility impairments are one of the most common types of disability faced by visitors to heritage sites, this study will look at how the changing views on disability discrimination have affected heritage sites by reviewing current legislation and comparing it with visits to heritage sites in the UK and the US. For this purpose, site visits looking at adaptations for mobility impairments were carried out at fifteen sites in the UK and six sites in the US. There are additionally three case studies: a comparison between a UK and a US early nineteenth-century naval vessel, a site with traditional adaptation methods, and one that has creatively designed access. Overall, both the UK and the US have adopted similar methods for creating disabled access. Yet, the research shows that although many sites have designed some type of access, there is no conformity as to how this access is achieved. In addition, many sites use the loopholes in legislation to ensure that little is changed in the physical material. In the end, it is evident that more must be done to find a compromise between accessibility and preservation.     

Image is everything: educator awareness of perceived barriers for students with physical disabilities in geoscience degree programs

ABSTRACT

This exploratory pilot study builds on the image issues associated with geoscience degrees (namely physical geography and geology) and the potential obstacles this creates for prospective applicants with physical disabilities; departmental faculty may not be aware of the exclusive image projected that is thought to attract more students. While the industry has moved from field-based data collection to more office-based observation and interpretation of those data, universities still heavily rely on “adventurous geoscience” in their marketing, depicting students tackling challenging environments. The context of perception issues within the geoscience discipline is illustrated through selected program promotional materials, and student registration data. These issues were used for the basis of our study survey, sent out to higher education geoscience educators, which asked questions reading fieldwork and accessibility of the curriculum. These surveys were followed up with semi-structured interviews, investigating educator awareness of the perceived importance of fieldwork within the curriculum. The awareness of accessibility issues were connected with opportunities to lower perceived barriers sufficiently to encourage students with disabilities to apply for geoscience degrees. Outcomes of this exploratory investigation are hoped to provide the springboard for further conversations amongst the geoscience community.     

Individual Accessibility Revisited: Implications for Geographical Analysis in the Twenty‐first Century

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 form, mobility, and individual accessibility. We consider some new possibilities for modeling individual accessibility and their implications for geographical analysis in the twenty‐first century.     

Space–Time Accessibility Under Conditions of Uncertain Travel Times: Theory and Numerical Simulations

Recently, several accessibility measures using the space–time prism concept have been suggested in the literature. These measures fail to take into account (i) the ability of individuals to adjust their activity–travel patterns in coping with constrained choice sets, (ii) uncertainty in the perception of travel times, (iii) temporal variability of travel times, and (iv) the influence of travel information on accessibility. The aim of the present article is to contribute to this literature by addressing these four shortcomings. Theory will be developed and illustrated using numerical simulations. The results suggest that the accessibility measure proposed in this article is a useful indicator of social inclusion in terms of the time individuals can spend to conduct their preferred activities. Moreover, accessibility is found to be affected by the presence of schedule delay penalties, restrictions in time allocation to activities, and the provision of travel time information in order to reduce uncertainty.     

Measuring Space-Time Accessibility Benefits within Transportation Networks: Basic Theory and Computational Procedures

Accessibility is a fundamental but often neglected concept in transportation analysis and planning. Three complementary views of accessibility have evolved in the literature. The first is the constraints-oriented approach, best implemented by Hägerstrand's space-time prisms. The second perspective follows a spatial interaction framework and derives “attraction-accessibility measures” that compare destinations' attractiveness with the travel costs required. A third approach measures the benefit provided to individuals by the transportation/land-use system. This paper reconciles the three complementary approaches by deriving space-time accessibility and benefit measures that are consistent with the rigorous Weibull axiomatic framework for accessibility measures. This research also develops computational procedures for calculating these measures within network structures. This provides realistic accessibility measures that reflect the locations, distances, and travel velocities allowed by an urban transportation network. Since their computational burdens are reasonable, they can be applied at the urban scale using a GIS.     

Measuring Space-Time Accessibility Benefits within Transportation Networks: Basic Theory and Computational Procedures

Accessibility is a fundamental but often neglected concept in transportation analysis and planning. Three complementary views of accessibility have evolved in the literature. The first is the constraints-oriented approach, best implemented by Hägerstrand's space-time prisms. The second perspective follows a spatial interaction framework and derives “attraction-accessibility measures” that compare destinations' attractiveness with the travel costs required. A third approach measures the benefit provided to individuals by the transportation/land-use system. This paper reconciles the three complementary approaches by deriving space-time accessibility and benefit measures that are consistent with the rigorous Weibull axiomatic framework for accessibility measures. This research also develops computational procedures for calculating these measures within network structures. This provides realistic accessibility measures that reflect the locations, distances, and travel velocities allowed by an urban transportation network. Since their computational burdens are reasonable, they can be applied at the urban scale using a GIS.     

Revisiting the structuring effect of transportation infrastructure: An empirical approach with the French railway network from 1860 to 1910

The development of the French railway network was mostly planned in a centralized manner. Despite the multiplication of travel opportunities, the local impact on the demographics is often given as an indirect effect of this spatial transformation. However, this “structuring effect” is still subject to controversies within the academia.

In this paper, we construct a historical geographic information system describing the evolution of the French network. We use it to compute accessibility measures based on network access and travel durations. We first observe that the network growth indeed achieved the various planning goals in terms of functional accessibility. We then present further evidences that the “structuring effect” of the train network on cities demographics is very limited if not null.     

珠江三角洲陆路运输网络效率测度及其演化

构建运输网络效率测度模型,对珠江三角洲27个县域单元1980年代以来运输网络效率的时空演化特征进行分析,结论表明:相较传统的通达性指标,网络效率指标在识别交通网络发展状况方面更有效;珠三角运输网络效率空间分异模式与通达性空间分异模式有较大差异,网络效率低值点和高值点同时存在于核心和外围地区;1988-2008年,随着珠三角陆路交通网络的发展,运输网络效率空间格局从原有的南北向"走廊"分布态势,转变为东西向面状均衡分布格局;运输网络效率水平大幅提升,网络效率平均值从4.42减少到1.41小时,变化率达到68.09%。各城市陆路运输网络效率与其城市发展关系表现为高度支撑型、基本支撑型、基本适应型及高度适应型四类。     

Access to the Information Age: Fundamental Decisions in Telecommunications Policy

As federal and state budget sheets show more red than black ink, the private sector is delivering more social services and even protecting rights. The experience of disability rights leaders during the past five years shows that the private sector will accept such obligations as long as the burden is evenly distributed throughout an industry. They will balk if it is not. The task of ensuring access and fairness for people with disabilities in an industry where equal allocation of social responsibility is difficult is illustrated by the continuing effort of disability rights leaders for accessibility to Information Age telecommunications products and services. The effort also highlights a recurring theme in public policy: Does equity mean that all Americans pay a little more so that those with disabilities gain full access, or does it mean that overall rates are kept low while those with special needs use adaptive devices? Each point of view was illustrated in the telecommunications policy debate of the 102nd Congress-and likely will shape that of the 103rd Congress as well.     

Strengths and weaknesses of accessibility instruments in planning practice: technological rules based on experiential workshops

Accessibility instruments can play a valuable role in urban planning practice by providing a practical framework for exploring and testing relationships between land use and transport infrastructure. Despite many available accessibility instruments, they are still not widely used in planning practice. This paper explores the background of this problem by examining the findings of a EU-funded study on the usability and usefulness of existing accessibility instruments. The study applied 16 instruments in local planning contexts according to a standardized process protocol. The outcomes of these so-called experiential workshops were analysed through a standardized measurement protocol, which included participant observation along with pre- and post-workshop practitioner questionnaires. This broad investigation presents a rich analytical tool for understanding how different types of accessibility measures, spatial resolutions of output and levels of comprehensiveness affect usability and usefulness. Based on this we propose 10 technological rules that (a) can be used directly in practice to improve usability of accessibility instruments and (b) can provide hypotheses to be examined in further academic studies. Our results suggest that instead of striving for the ultimate accessibility measure, it would be more effective to identify which measures could successfully serve different user needs in accessibility planning.     

河南省人口分布与乡镇可达性空间耦合特征

人口作为区域发展的内在因素,交通可达性提高将有利于促进人口或劳动力要素的自由流动和优化配置。在考虑土地利用及地形因素的基础上,采用包含乡村道的交通网络数据集,应用改进的成本距离计算方法,分析河南省乡镇可达性及其分布特征;通过乡镇可达性与人口密度的空间叠加,揭示人口分布与可达性的空间耦合特征。结果表明：①各乡镇可达性总体呈现明显的圈层分布,可达性值由内向外逐渐降低;时段越短,内部差异越大,交通指向越明显。②乡镇可达性与人口密度在各时间圈呈现正相关关系,可达性与人口分布集聚产生作用的最大时间距离为1.5h。③人口与交通可达性的空间耦合呈现较明显的半环状分布,社会经济指向性明显。④交通可达性对人口变化的影响具有时间阶段性和区域差异性。     

“Where Can a Gypsy Stop?” Rethinking Mobility in Scotland

Abstract: This article examines mobile practices of Scottish Gypsy/Travellers and analyses how their mobility affects their socio‐spatial access to participation within Scottish society. It explores how different representations of mobility set up boundaries and limitations on travel, unravels everyday practices of mobility by Gypsy Travellers and discusses their embeddedness within Scottish society and culture. The discussion draws on empirical research results to assess attempts to accommodate mobile practices of Travellers within existing structures of political and economic organisation. It exposes dominant “punctual” understanding of movement, which lacks information about what happens during the move and overlooks important elements of ambulant lifestyles. Findings from this study suggest that formalised definitions of travel privilege specific forms of mobility to the neglect of the others and serve to perpetuate the marginalised identities of itinerant people. The paper concludes with theoretically informed observations about the new ways of re‐connecting policies tackling disadvantage with mobility.     

Note on draft plan For institute of geography

A number of measures of accessibility are applied to the road and transport networks of the N.W. Highlands and Islands. The concept of ‘accessibility’ is interpreted at the regional scale and in a physical, rather than a behavioural, sense. Although other indices are briefly mentioned, three basic approaches are examined in greater detail: travel timings from a central point, shortest paths through the network between every pair of nodes, and potentials. From all the methods discussed, there is a large degree of consensus on the spatial patterns of accessibility in the region.     

A Surface-Based Approach to Measuring Spatial Segregation

Quantitative indices of residential segregation have been with us for half a century, but suffer significant limitations. While useful for comparison among regions, summary indices fail to reveal spatial aspects of segregation. Such measures generally consider only the population mix within zones, not between them. Zone boundaries are treated as impenetrable barriers to interaction between population subgroups, so that measurement of segregation is constrained by the zoning system, which bears no necessary relation to interaction among population subgroups. A segregation measurement approach less constrained by the chosen zoning system, which enables visualization of segregation levels at the local scale and accounts for the spatial dimension of segregation, is required. We propose a kernel density estimation approach to model spatial aspects of segregation. This provides an explicitly geographical framework for modeling and visualizing local spatial segregation. The density estimation approach lends itself to development of an index of spatial segregation with the advantage of functional compatibility with the most widely used index of segregation (the dissimilarity index D ). We provide a short review of the literature on measuring segregation, briefly describe the kernel density estimation method, and illustrate how the method can be used for measuring segregation. Examples using a simulated landscape and two empirical cases in Washington, DC and Philadelphia, PA are presented.     

Measuring children's independent mobility: comparing interactive mapping with destination access and licence to roam

Children's independent mobility (IM) lacks a standardised definition and measurement protocol. Interactive mapping applications can capture geographically defined mobility data. In this study of 219 children, independent parental licences (IM Licence) and allowances to travel to certain locations unsupervised (IM Index) were collected through a questionnaire, and compared to IM-roaming areas derived from the Visualisation and Evaluation of Route Itineraries, Travel Destinations, and Activity Spaces (VERITAS-IM) mapping application. Significant relationships were found between the VERITAS-IM-derived measures and traditional measures of IM (IM Licence and IM Index). Results suggest the perceived degree of children's IM is heavily dependent on the assessment method and a combination of methods should be considered.