SPACE–TIME MEASURES OF DEMAND FOR SERVICE: BRIDGING LOCATION MODELLING AND ACCESSIBILITY STUDIES THROUGH A TIME‐GEOGRAPHIC FRAMEWORK

Demand for service in location modelling is often evaluated based on the spatial proximity of fixed and static reference locations of demand (e.g. home) to a facility, which ignores person‐specific activity–travel patterns and the temporal changes in demand for service throughout the day. To address these limitations, this study draws upon recent developments in space–time measures of individual accessibility to explore the spatial and temporal structures of demand by considering individuals' space–time constraints and impact of existing urban structures. Based on a time‐geographic framework, eight space–time demand measures were developed and compared with three conventional location‐based demand measures for 12 hospitals through an empirical study conducted in Columbus, Ohio. The results show that geographic proximity between clients' home and facilities may not be an effective indicator for service demand, and conventional demand measures tend to underestimate potential demand for service in most situations. The study concludes that space–time demand measures that take into account people's activity‐travel patterns in space–time would lead to better estimation of demand for service in most cases.     

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.     

Accessibility interrupted: the Shimshal road,Gilgit‐Baltistan,Pakistan

Geographers working in mountainous northern Pakistan note that gains in accessibility following the Karakoram Highway's official opening in 1978 significantly reshaped social organization, economic activity, and land use across the region. These valuable regional‐scale analyses provide few insights regarding the contingent and variable ways new roads are conceived and experienced at the community and household level by the people whose mobility they drastically impact. This article addresses that limitation of regional research by focusing on an individual agricultural community called Shimshal that in 2003 completed a 40‐kilometre link‐road connecting it to the highway. Drawing from qualitative information gathered before and after the Shimshal road's completion, we briefly describe the community's motivation for constructing the road, villagers’ accessibility‐related hopes and concerns as it was being built, and some of the social, cultural, and economic changes that followed the road's completion. The article concludes by summarizing the community's response so far to landslide‐induced destruction of over 20 kilometres of the Karakoram Highway which, since January 2010, has left community members without vehicular access to the rest of Pakistan just seven years after their link‐road's completion.     

Dealing with Timing and Synchronization in Opportunities for Joint Activity Participation. 公共活动参与机会中实时性与同步性处理

The ability of people to access opportunities offered by the built environment is circumscribed by various sets of space–time constraints, including the requirements to meet other persons at particular times and places to undertake activities together. While models of space–time accessibility recognize that joint activities may constrain the performance of activities in space and time, their specifications do not explicitly acknowledge the opportunities that individuals of a group have for joint activity participation. Therefore, this article focuses on joint activity participation and argues that collective activity decisions are the outcome of a complex process involving various aspects of timing, synchronization, and social hierarchy. The utility‐theoretic model proposed here quantifies the extent to which opportunities can be jointly accessed by a particular group of people within a specific time period. Central to the approach are three key variables: the attractiveness of an opportunity, the time available for activity participation, and the travel time to an activity location. Because of the multiperson character of joint activities, the determination of these variables is subject to individual preferences, privileges, and power differentials within a group. Specific attention is given to how time‐of‐day and synchronization effects influence the opportunities accessible to a group of individuals. The impact of these factors on joint accessibility is illustrated by a real‐world example of an everyday rendezvous scenario. The outcomes of a simulation exercise suggest that time‐of‐day and synchronization effects significantly affect the benefits that can be gained from opportunities for joint activities.     

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.     

Land suitability assessment for locating industrial parks: a hybrid multi criteria decision‐making approach using Geographical Information System

Industrial areas play a critical role in urban and regional planning, especially for developing countries where reliable strategies for these areas can promote economic and environmental efficiency. The present study provides an integration of hybrid multi‐criteria decision‐making (MCDM) theories and Geographical Information System (GIS) processes in order to assess the suitability of an industrial location. Unlike traditional models, an efficient decision analysis demands handling uncertainties and considering dependencies between criteria. The proposed MCDM framework uses fuzzy theory because of the vagueness of experts' judgements. Moreover, Decision‐Making Trial and Evaluation Laboratory (DEMATEL) is employed to investigate interrelationships among the criteria. In the proposed empirical solution, analytic network process (ANP) principles are used to deal with systematic interactions. We considered several factors such as accessibility, topography, proximity, and socioeconomic characteristics in the decision‐making procedure for a sustainable industrial park. The system is applied to Hamadan province, Iran to determine appropriate locations that are the results of the aggregation of criteria maps in a GIS environment. The results demonstrate that accessibility and economic indicators are essential for choosing an industrial park's location. Additionally, the proposed method can be applied for an efficiency evaluation of available industrial parks.     

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.     

Estimating the Size of Social Networks

It is notoriously difficult to define and estimate the size of individuals' social networks. Methods are suggested for estimating the size of such networks, using known rates of mobility together with survey data on the number of acquaintances of individuals who have recently moved. Special attention is given to the likely correlation between mobility rates and network size. Estimates are found to be consistent with previous estimates in the literature. The relation of this approach to multiplicity sampling and to “the small-world problem” is also discussed.     

General practice access in regional and remote Australia for ageing populations

Identifying and removing access barriers to the timely provision of comprehensive health care is increasingly important for the wellbeing of Australia's rapidly ageing and frail populations, particularly those in non‐metropolitan settings. This study has examined if current general practice (GP) locations in non‐metropolitan South Australia (SA) and Western Australia (WA) are geographically accessible to the rapidly growing frail and prefrail populations known to have a high level of health service use and reduced mobility. Geospatial analysis linking 60‐kilometre GP service catchments, 2016 population counts, and 2027 population projections has estimated that the size of the frail and prefrail population that live outside these GP service catchments will double, reaching 7,800 people by 2027. The maldistribution of GP locations was most evident in WA. As regional and remote populations continue to age, the challenge of health service provision, including geographic access to care, must be resolved to ensure that populations in these areas have the best opportunity to age well. Geospatial methods linking service and demographic information, such as the approach used in this analysis, can aid in planning the equitable provision of health care for older Australians.     

A Socio‐Geographic Perspective on Human Activities in Social Media

Location‐based social media make it possible to understand social and geographic aspects of human activities. However, previous studies have mostly examined these two aspects separately without looking at how they are linked. The study aims to connect two aspects by investigating whether there is any correlation between social connections and users' check‐in locations from a socio‐geographic perspective. We constructed three types of networks: a people–people network, a location–location network, and a city–city network from former location‐based social media Brightkite and Gowalla in the U.S., based on users' check‐in locations and their friendships. We adopted some complexity science methods such as power‐law detection and head/tail breaks classification method for analysis and visualization. Head/tail breaks recursively partitions data into a few large things in the head and many small things in the tail. By analyzing check‐in locations, we found that users' check‐in patterns are heterogeneous at both the individual and collective levels. We also discovered that users' first or most frequent check‐in locations can be the representatives of users' spatial information. The constructed networks based on these locations are very heterogeneous, as indicated by the high ht‐index. Most importantly, the node degree of the networks correlates highly with the population at locations (mostly with R² being 0.7) or cities (above 0.9). This correlation indicates that the geographic distributions of the social media users relate highly to their online social connections.     

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.     

The geographies of UK university halls of residence: examining students' embodiment of social capital

Recent investigations into ‘student geographies’ have recognised the complex ways in which students from different backgrounds go about ‘fitting in’ among their peers within university-managed accommodation. Halls have been characterised in the literature as highly pressurised spaces in which multiple (and potentially conflicting) identities can perpetuate disadvantage through incongruous accessibility to student-centric social activities and behaviours. This paper joins these debates by critically examining universities' ‘Student Accommodation’ web pages alongside qualitative interviews in order to question notions of halls being inclusive and encouraging a cultural mix. Using Bourdieu's reading of social capital this paper suggests that, while these spaces may perpetuate disadvantaged access to social capital, some students may transcend this, drawing on other forms of non-student social capital which legitimises their position among their peers in halls. This adds to previous discussions of ‘difference’ by highlighting the power of social capital in transforming individuals' positions within social groupings.     

‘IT IS MY HOME. I WILL DIE HERE’: TOURISM DEVELOPMENT AND THE POLITICS OF PLACE IN LIJIANG,CHINA

Although “home” is an established topic in the literature, what home means for an in situ, non‐travelling population that nevertheless is confronted by the influx of great numbers of tourists and migrants is an important question that has not been widely researched. This article examines the construction and practice of home in a highly mobile world, in the case of Lijiang Ancient Town, a World Heritage site in Yunnan, China. Situating Lijiang in the context of China's emerging consumer society, this article has two objectives. First, I will sketch a conceptual framework within which to address the construction of home in relation to mobility, displacement and socioeconomic changes. The second objective is to examine the multiple ways in which Lijiang's town residents dwell in displacement. Even as Lijiang ancient town largely falls into the hands of migrant businesspersons, town residents employ spatial strategies to maintain a public–private boundary, reconcile themselves to living under the same roof with tourists, or forsake their homes for economic benefit. Hence, this article contributes to the geographies of everyday life by illustrating individuals' multiple forms of strategic rationalization in handling socio‐spatial transformation.     

Smart growth strategies,transportation and urban sprawl: simulated futures for Hamilton,Ontario

North American cities have undergone dramatic changes over the last century. Locations that were once inconvenient have become accessible through extensive road networks leading to population decentralization from the traditional urban centre to suburbia, creating polycentric sprawls from once monocentric communities. Hamilton, Ontario is one such city. The decentralization and urban decline of the city is widely attributed to sprawling development. This change in the sociospatial structure creates challenges for transportation planners as we see greater automobile dependency, greater commuting distances and increased congestion. Smart growth policies such as urban residential intensification (URI) aim to increase population densities in the urban core. This exploratory study estimates the benefits of such policies from a transportation aspect. It is predicted that the City of Hamilton will experience household growth of approximately 80,000 households over the period 2005–2031. Using IMULATE, an integrated urban transportation and land‐use model, a variety of development scenarios model this anticipated growth. Changes in vehicular emissions, traffic congestion and energy consumption as a result of URI are examined. Models of the land‐use/transportation relationship demonstrate how increasing population densities within a city's urban centre drastically reduce congestion, emissions and gasoline consumption.     

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。     

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.     

医院可达性评价与规划——以江苏省仪征市为例

医院作为公共服务设施的一个重要组成部分,为居民提供了必不可少的医疗机会,其空间分布以及可达性的优劣,直接影响到居民能接触到医院的机会和方便程度。把可达性的概念引入到医院规划中,利用Mapinfo公司的控件MapX和Borland公司的可视化编程语言Delphi,开发了基于时间最短的路径选择信息系统,生成了医院可达性的等时线图和医院服务范围图,通过该系统可直观的看到区域内任何一点到达同一级医院所花费的最短时间以及通过的路径。以江苏省仪征市的医院为例,运用该系统对医院的可达性进行了评价,并提出了医院的规划方案。     

Evolutionary Series of Physical-Geographic Phenomena and Finite Automata

Evolutionary series of the type rill—furrow—gully—ravine are analyzed in terms of the theory of finite automata, in which the input and state at time t determine the output and state at time t + 1. External factors of evolution are treated as the inputs of the automaton. If the probabilities of one state's turning into another state are considered, the model becomes a simple Markov chain or, in the language of the theory of automata, a probabilistic finite automaton. It is shown on the basis of a matrix of transition probabilities that after a certain length of time the system reaches a state of equilibrium, or ergodic state.