Accessibility Measurement in Transportation Networks and Application to the Seoul Bus System

This study presents an algorithm for measuring the time‐distance accessibility based on the flow data of actual transportation networks and examines resulting accessibility distributions. Specifically, we construct an extended graph of the transportation network to take into account not only the average speed and transfer time extracted from the data set but also various possible trajectories taken via transfers. Employing the modified Floyd algorithm which finds the shortest time distance, we compute the time‐distance accessibility of every bus stop in the Seoul bus system, which yields distinctive skew distributions. We then introduce a time‐distance cutoff to focus on effective connections and probe the emergent spatial distributions as the cutoff is varied. Revealed are the characteristic scales as well as spatial structures of the system. It is suggested that the time‐distance accessibility can serve as a significant measure to describe and predict the urban land use pattern.     

Slum Wars of the 21st Century: Gangs,Mano Dura and the New Urban Geography of Conflict in Central America

The political economy of violence in Central America is widely perceived as having undergone a critical shift during the past two decades, often pithily summarized as a movement from ‘political’ to ‘social’ violence. Although such an analysis is plausible, it also offers a depoliticized vision of the contemporary Central American panorama of violence. Basing itself principally on the example of Nicaragua, the country in the region that is historically perhaps most paradigmatically associated with violence, this article offers an alternative interpretation of the changes that the regional landscape of violence has undergone. It suggests that these are better understood as a movement from ‘peasant wars of the twentieth century’ ( Wolf, 1969 ) to ‘urban wars of the twenty‐first century’ ( Beall, 2006 ), thereby highlighting how present‐day urban violence can in many ways be seen as representing a structural continuation of past political conflicts, albeit in new spatial contexts. At the same time, however, there are certain key differences between past and present violence, as a result of which contemporary conflict has intensified. This is most visible in relation to the changing forms of urban spatial organization in Central American cities, the heavy‐handed mano dura response to gangs by governments, and the dystopian evolutionary trajectory of gangs. Taken together, these processes point to a critical shift in the balance of power between rich and poor in the region, as the new ‘urban wars of the twenty‐first century’ are increasingly giving way to more circumscribed ‘slum wars’ that effectively signal the defeat of the poor.     

Urban Systems of Accumulation: Half a Century of Chilean Neoliberal Urban Policies

We analyse a half‐century of Chilean urban reforms to explain the introduction of a system of urban accumulation by dispossession of public resources and opportunities. Three stages have been conceptualised in the imposition of a neoliberal creative‐destructive process: proto‐neoliberalism, roll‐back and roll‐out periods. Empirical studies have traditionally analysed this process by examining a single urban policy's evolution over time. In this paper, we go beyond these types of studies by performing a systemic analysis of multiple urban policy reforms in Santiago, Chile. We use a genealogical thematic analysis to track changes in laws, government programmes and planning documents from between 1952 and 2014. Our analysis identifies different “urban systems of accumulation” by looking at the interplay of four urban policies: (1) urban planning deregulation; (2) social housing privatisation; (3) devolution of territorial taxes; and (4) decreased public service provision. Moreover, our multidimensional policy analysis in Santiago characterises a more radical, fourth expression in the creative destruction process of “accumulation by dismantling”. Consequently, we advocate for more multidimensional urban policy research that goes beyond a three‐period analysis in order to gain a deeper understanding of contemporary neoliberal creative‐destructive processes in variegated geographies.     

南京市社区服务设施可达性的空间格局与低收入社区空间剥夺研究

社区服务设施的空间可达性事关城市公共资源分配的社会公平与公正,是反映城市居民生活质量的重要标志。以南京市居住用地作为基本分析单元,对南京市的教育、医疗、商业和公园绿地四大类社区服务设施的空间可达性进行分析;并通过对相关低收入社区的实地调研,研究城市边缘区低收入群体的服务设施空间剥夺问题。研究表明：南京市四类服务设施的可达性水平均呈现出由城市中心区向郊区衰减的空间分异格局;较低的社区服务设施可达性不仅直接造成低收入社区居民对社区服务设施较低的满意度,导致其空间剥夺感的产生,还极大地阻碍着社区归属感的形成,导致社区居民强烈的迁居欲望,在他们较低的支付能力下进一步加剧其空间剥夺感。政府未来在规划面向低收入群体的保障性社区时,更应注重相关服务配套设施建设,做到社会与空间的公正性。     

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.     

基于GIS的徐州市城乡交通基础设施通达性研究

以徐州市城乡交通网络数据为数据源,利用GIS空间分析技术,选取长度-半径维数、分枝维数、距离可达性、时间可达性和可达性系数5个指标对该区交通网络的空间形态、空间分布、距离关系、时间关系等进行多角度分析。结果表明,徐州市城乡交通网络长度-半径维数呈现明显的空间分异,徐州市区及周边地区交通网络密度最大,其次是东部,西北部县域交通网络密度最小,分枝维数和长度-半径维数的空间分布基本一致。区内各节点的时间和距离可达性均随距离徐州市区的增大而增大,通达性高于全区平均水平的节点有徐州市辖区各节点,接近全区平均水平的节点有邳州市、沛县和睢宁县,而丰县和新沂市的通达性水平则低于全区平均通达性水平。     

Suburbanization and sprawl in post-socialist Belgrade and Sofia

The goal of this research is to examine the processes of suburbanization and sprawl in two post-socialist capital cities in Southeast Europe – Belgrade, Serbia and Sofia, Bulgaria. Our analysis begins with a survey of relevant historical developments in the two cities, which illustrates the impact of major political, economic and social drivers on urban development processes and form. We follow this with an empirical study aimed at identifying contemporary features of peri-urban processes occurring in the two cities. Specifically, we explore spatial patterns, general population trends and changes in urban densities. Our study confirms earlier observations by other researchers that processes of suburbanization are occurring in Belgrade and Sofia. Yet this research goes further and emphasizes the specific combination of conditions inherited from the era of state socialism and the features of South-east European urban culture. Thus regarding the form of urban expansion, we observe relatively weak trends of sprawl with strong local specifics. On this basis, we discuss our empirical results with the objective of identifying the specifics of studied processes in Belgrade and Sofia as a grounds for the articulation of an appropriate policy framework.     

Placing Transport Workers on the Agenda: The Conflicting Logics of Governing Mobility on Bishkek's Marshrutkas

Transport workers are conspicuously absent from both mobilities and urban studies literature. This paper therefore starts out with a double critique. First, transport workers, primarily drivers, are largely disregarded in mobilities and urban transport research. Second, the literature we find on transport workers—mostly based in empirical settings in the global South—remains outside recent and ongoing debates in critical urban transport studies. Providing empirical insights from post‐Soviet Central Asia, this paper strives to close these gaps and delve into the struggles and cleavages that structure informal transport workers’ positions and livelihoods. We argue that the diverse and contradictory logics that govern urban mobility affect the livelihoods and working conditions of informal transport workers, as well as their choices and motivations. These, in turn, significantly shape mobility provision, in terms of urban transport's (lack of) affordability, accessibility, convenience and safety.     

SPATIAL DIFFERENTIATION OF POPULATION DEVELOPMENT IN A DECLINING REGION: THE CASE OF SAARLAND

We increasingly understand the causes of population decline: these can be, among others, processes of deindustrialization, decreasing fertility or the succession of a city through the stages of urban life as the city matures. However, we are still insufficiently able to explain why differences still exist between cities within regions experiencing the same macro‐processes and between cities of the same “level of maturity”. This research addresses this intra‐regional differentiation in population development in the declining former mining region of Saarland (Germany). Quantitative and qualitative analysis reveals that the differentiation in current decline stems from (1) the differentiated population development trajectories of the past, with a massive population boom followed by an aged and declining population in the industrial municipalities; and (2) the spatial distribution of amenities over the region; and (3) the spatial distribution and accessibility of housing opportunities steering migration flows. The latter are not necessarily concentrated in those areas that are attractive. Rather, the distribution of these housing opportunities strictly follows the planning logic of the supra‐local institutional framework, with a concentration of housing within easy access of major transportation infrastructure and in larger centres. The case study thus reveals that the mechanisms behind this intraregional differentiation are much more complex than often portrayed in the urban development and decline debate.     

Measuring Accessibility for People with a Disability

This paper discusses some of the inherent problems associated with measuring accessibility for people on a landscape of surfaces, barriers, and travel modes. Along with this discussion we propose a new perspective for measuring accessibility with a focus on people with differing abilities. Even though our focus is on people with a physical disability, such an approach can be easily extended and is able to be generalized to other needs and differences. Traditional measurements of accessibility are flawed, as they fail to directly account for mobility and physical differences among people. They ignore structural barriers and individual mobility limitations that affect travel time, effort, and even successful completion. To make sense of this dilemma, we propose an accessibility measurement framework that includes measures of absolute access, gross access, closest assignment access, single and multiple activity access, probabilistic choice access, and relative access. Most of these measures of access have been proposed by others, but our framework attempts to codify an approach that helps to overcome weaknesses in using only the absolute access measurement currently used in ADA compliance. Such measures can be used to map accessibility as well as to help select the mitigation or renovation projects that yield the greatest increase in accessibility for people with disabilities. We argue that for many urban and building design problems providing absolute access for people with physical disabilities should be accompanied by the use of a relative access measurement, so that removing barriers can be done in the order that provides the greatest improvement in access for a given level of expenditure.     

Gender and daily mobility in a New Zealand city, 1920–1960

Although it is widely accepted that transport—like other social practices—is gendered, the concept of gender used in transport research is often one‐dimensional, with the focus on gendered variations in behaviour rather than on gendered meaning and identities. In this paper, I develop a more complex and multi‐stranded way of approaching the issue of gender and transport (or rather, daily mobility). A case study of a neighbourhood in the New Zealand city of Dunedin in the early decades of last century is presented to explore how the practices of daily mobility constituted gender. A three‐part concept of gender is developed as a basis for analysis: gender as a pattern of social relations, a cultural system of meaning and a component of personal identity. This is then used to analyse a collection of sixty oral histories. The period 1920–1960 is particularly interesting; in these decades extensive and widely used public transport systems (notably electric trams) shared urban streets with bicycles and pedestrians, and the emerging private modes of motorcycle and motor car. As new transport technologies were taken up, they offered the opportunity for new social practices to be formed around their use, for cultural meanings to be assigned to the technologies and for embodied individual subjectivities to be constructed. I argue that we can usefully interpret the shifting patterns of transport use through the lens of gender, and that we can come to understand the process by which gender is constructed by attention to everyday trip‐making and presence on the street.     

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.     

Linking Gentrification and Labour Market Precarity in the Contemporary City: A Framework for Analysis

The interplay between intensifying labour market precarity and gentrification constitutes a hitherto under‐researched topic in the fields of labour and urban geography. To rectify this lacuna, we argue that gentrification and labour flexibilisation are both socio‐spatial manifestations of capital's efforts to confront crises of accumulation. Distinguishing between what we call “weak” and “strong” links between them, and drawing upon the concepts of “gentrification‐supporting” and “gentrification‐fostered” labour flexibility, we outline a framework for connecting gentrification and precarity. This allows us to make links between the restructuring of the built environment and the reorganisation of work in the post‐industrial city; it also allows us to show how workers, through their agency, can shape rent gaps in the contemporary city.     

高速铁路对湖南城市群可达性的影响

引入可达性的概念,以现阶段与预期2030年的湖南城市群综合铁路网数据为基础,选取加权平均旅行时间、经济潜力和日常可达性3个度量指标,比较分析了高速铁路的发展对湖南城市群城际间8城市可达性的影响。结果表明:高速铁路大大缩短了城际之间的时空距离,将全面提升湖南区域可达性水平,促进区域均衡化空间结构的形成;另一方面,尽管高速铁路将推动多中心空间结构的形成,但对湖南城市可达性水平的影响具有明显的区域差异,可分为两个层级,各城市在新的交通格局下应抓住机遇,探寻符合自身特点的发展道路。     

基于可达性与场强模型的中国地级以上城市空间场能测度

空间场能是区域中心城市借助区域联系通道带动腹地发展而产生的"势能差"的抽象表达,可有效刻画区域发展格局与空间差异。采用主成分分析法与指标体系计算城市结节性指数,借助ArcGIS软件平台,采用累积耗费距离法、K阶数据场和ESDA等方法,综合测度了中国287个地级以上城市可达性与空间场能,并分别从省域、市域、县域等单元探讨了中国东中西三大地带与南北场能差异的空间格局与演变特征。结果表明:中国地级以上城市的可达性条件不断改善,平均可达性时间从1991年的246.98min缩短为2010年的193.43min。空间场能显著增长且空间分异性显著,分布结构由单核向多极网络状形态转变。县域场能存在显著的空间极化现象,场能热点区域的分布呈现显著的热点-次热点-次冷点-冷点自东向西带状分布的格局。依据场能分析结果,将全国划分为3个一级经济区和26个二级城市经济区。     

PATHS IN TRANSNATIONAL TIME-SPACE: REPRESENTING MOBILITY BIOGRAPHIES OF YOUNG SWEDES

This article sets out to capture and describe individual transnational mobility from a long‐term, biographical perspective. The purpose is to discuss the use of a time‐geographical form of notation to represent people's transnational mobility as paths in time and space, and to demonstrate how such representations can contribute to explaining some of the dynamics of longdistance mobility. An advantage of using time‐space paths is that several aspects of an individual's travel biography can be represented in a single image: intensity and extensity are immediately evident, and the temporal and spatial relationships between the various mobility actions are made visible. Using data describing all transnational trips taken during childhood and adolescence by sixty‐two Swedish youth with different backgrounds, three aspects of how trajectories develop over time are discussed in more detail. The first concerns overall change in travel pattern with time. A dominant pattern of increase in travel with increasing age is observed, indicating the importance of further investigating how travel behaviour is related to experience and life‐course transitions. Second, sequential relationships between migration and temporary mobility are examined. In spite of the relatively small number of respondents, a wide range of such relationships are disclosed in the material. Third, regularity and repetition in long‐distance travel patterns is discussed as an increasingly important aspect of contemporary transnational mobility. Among these young people, highly regular travel is often motivated by enduring long‐distance social relationships, but is also generated by leisure or holiday travel alone.     

Using Fractal Dimensions for Characterizing Intra‐urban Diversity: The Example of Brussels

The objective of this paper is to compare fractal‐based parameters calculated by different fractal methods for urban built‐up areas and to link the observed spatial variations to variables commonly used in urban geography, urban economics, or land‐use planning. Computations are performed on Brussels, Belgium. Two fractal methods (correlation and dilation) are systematically applied for evaluating the fractal dimension of built‐up surfaces; correlation is used to evaluate the fractal dimension of the borders (lines). Analyses show that while fractal dimension is ideal for distinguishing the morphology of Brussels, each estimation technique leads to slightly different results. Interesting associations are to be found between the fractal dimensions and rent, distance, income, and planning rules. Despite its limitations, fractal analysis seems to be a promising tool for describing the morphology of the city and for simulating its genesis and planning. The model is robust: it replicates the urban spatial regularities and patterns, and could hence fruitfully be integrated into intra‐urban simulation processes.     

公交站点可达性测度及其在停车分区中的应用

考虑公交与小汽车方式间的可达性差异,提出了依据公交服务水平调控小汽车可达性的停车分区思路,以期实现对小汽车方式的合理限制,支持城市公交优先发展。首先根据居民出行对不同类型公交站点具有不同可达性需求,将以需求点为圆心、站点时空可接近距离为半径的覆盖范围作为基本分析单元,构建基于微观个体时空约束下的公交站点可达性测度模型。其次借助ArcGIS,以昆明市公交网络数据为基础,对站点可达性空间分布特征进行可视化分析,所得结果与城市用地开发整体特征相吻合,验证了模型的合理性。最后以公交可达性水平为主要依据划分停车供给分区,从而对不同分区停车泊位供给的科学配置提供支撑。     

SPATIAL MOBILITY AND COMMUTING: THE CASE OF TWO‐EARNER HOUSEHOLDS*

ABSTRACT We examine the effects of the spatial configuration of workers' residence and workplace location on intraregional residential and job moving decisions of workers belonging to two‐earner households. We hypothesize that two‐earner households' residential mobility depends positively on the commuting distance of both spouses, but negatively on the distance between workplaces. Further, we hypothesize that workers' job mobility depends positively on the worker's commuting distance, negatively on the spouse's commuting distance, and positively on the distance between workplaces. Using data for Denmark, it appears that these hypotheses hold, and that the effects of the spatial configuration are rather large.     

Bipolar antagonism and multipolar coexistence: framing difference and shaping fear in two Caribbean cities

This article proposes a new approach to urban geographies of fear, focusing on the connection between fear and cultural understandings and representations of difference. Much of the existing work on the relationship between fear, urban space, and social difference tends to take social difference as more or less given. In this article, we argue that how differences (such as ethnic, political or class differences) are framed has strong implications for geographies of fear. The article suggests that dualistic and nondualistic framings of difference influence levels of fear and that this becomes visible in the use and perceptions of urban space, and in the built environment through the erection of physical barriers. These spatial factors, as they limit mobility and interaction, tend to reproduce the specific framing of difference. Two discursive modes of representing difference are discussed. The first, ‘bipolar antagonism’, is based on a dualist rhetoric of irreconcilable opposites. This is contrasted with ‘multipolar co-existence’, in which social categories are understood as multiple or hybrid, with flexible or fluid boundaries, and as not necessarily antagonistic. This argument is elaborated through a comparative analysis of social–cultural and spatial processes in two Caribbean cities: Kingston, Jamaica, and Paramaribo, Suriname.