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.     

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.     

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.     

景点可达性对不同出游时间游客流动的影响研究——以西安市为例

景点可达性是实现游客流动的先决条件,受到旅游可利用时间的影响和制约,游客流动亦表现出明显的出游时间异质性,探讨出游时间制约下景点可达性如何影响游客流动,对于进一步深化厘清旅游目的地发展机制,完善旅游交通配置和布局,促进城市旅游业发展具有重要意义.本文以典型旅游城市西安为研究区域,综合利用百度出行实时数据、网络游记数据和...     

Space–Time Sequential Similarity for Identifying Factors of Activity‐Travel Pattern Segmentation: A Measure of Sequence Alignment and Path Similarity

The article develops a new method that compares activity‐travel patterns in both terms of the sequential order of activities and the shape of activity‐travel trajectory in time and space. The similarity of the list of activities and their order between activity‐travel patterns are computed by a sequence alignment method. The shape of activity‐travel trajectory is compared between the patterns using a path similarity technique that captures the direction and speed of a movement from the current location and the duration of staying at each location. The comparison results, therefore capture how people move around in three‐dimensional space–time choreography that indicates how people conduct which activities in what order. A total of 1,000 individuals are sampled from the data of 2016 Household Travel Survey, South Korea. The data provide the information of individual activity‐travel behavior and personal characteristics. The suggested method computes the pairwise distance matrix, and Ward clustering algorithm segments the pattern groups of similar activity sequences and space–time trajectories. A CHAID analysis then associates personal and household characteristics with the pattern groups to identify important factors for the segmentation. The analysis provides a significant implication in both terms of research and practice in transportation.     

Geographic information system‐based evaluation of spatial accessibility to maternal health facilities in Siaya County,Kenya

Maternal mortality is a major problem in middle‐income and low‐income countries, and the availability and accessibility of healthcare facilities offering safe delivery is important in averting maternal deaths. Siaya County, in Kenya, has one of the highest maternal mortality rates in the country—far more than the national average. This study aimed to evaluate geographic access to health facilities offering delivery services in Siaya County. A mixed‐methods approach incorporating geographic information system analysis and individual data from semi‐structured interviews was used to derive travel time maps to facilities using different travel scenarios: AccessMod5 and ArcGIS were used for these tasks. The derived maps were then linked to georeferenced household survey data in a multilevel logistic regression model in R to predict the probability of expectant women delivering in a health facility. Based on the derived travel times, 26 per cent (13,140) and 67 per cent (32,074) of the estimated 46,332 pregnant women could reach any facility within one and two hours, respectively, while walking with the percentage falling to seven per cent (3,415) and 20 per cent (8,845) when considering referral facilities. Motorised transport significantly increased coverage. The findings revealed that the predicted probability of a pregnant woman delivering in a health facility ranged between 0.14 and 0.86. Significant differences existed in access levels with transportation‐based interventions significantly increasing coverage. The derived maps can help health policy planners identify underserved areas and monitor future reductions in inequalities. This work has theoretical implications for conceptualising healthcare accessibility besides advancing the literature on mixed methodologies.     

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.     

Space-Time and Integral Measures of Individual Accessibility: A Comparative Analysis Using a Point-based Framework

Conventional integral measures of accessibility, although valuable as indicators of place accessibility, have several limitations when used to evaluate individual accessibility. Two alternatives for overcoming some of the difficulties involved are explored in this study. One is to adapt these measures for evaluating individual accessibility using a disaggregate, nonzonal approach. The other is to develop different types of measures based on an alternative conceptual framework. To pursue the former alternative, this study specifies and examines eighteen gravity-type and cumulative-opportunity accessibility measures using a point-based spatial framework. For the latter option, twelve space-time accessibility measures are developed based on the construct of a prism-constrained feasible opportunity set. This paper compares the relationships and spatial patterns of these thirty measures using network-based GIS procedures. Travel diary data collected in Columbus, Ohio, and a digital data set of 10,727 selected land parcels are used for all computation. Results of this study indicate that space-time and integral indices are distinctive types of accessibility measures which reflect different dimensions of the accessibility experience of individuals. Since space-time measures are more capable of capturing interpersonal differences, especially the effect of space-time constraints, they are more “gender sensitive” and helpful for unraveling gender/ethnic differences in accessibility. An important methodological implication is that whether accessibility is observed to be important or different between individuals depends heavily on whether the measure used is capable of revealing the kind of differences the analyst intends to observe.     

信息技术对南京城市居民休闲活动与出行的影响

从网络休闲角度出发,运用结构方程模型就信息技术对南京城市居民休闲活动与出行的影响进行实证研究,探索居民社会经济属性、信息化水平、网络休闲活动和出行之间的关系。结果显示:信息技术对南京城市居民的休闲活动已经产生了广泛的影响;而网络休闲活动的增加也确实减少了居民每日的非必要性出行时间,说明对居民出行有替代或修正性的影响;此外,居民的社会经济属性是影响居民网络休闲活动和出行选择的根本,其中,年龄和学历,学历和收入,分别是当前影响居民网络休闲活动状况以及居民出行方式选择的关键。     

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.     

HISTORIOMETRICS,HISTORICAL AND CARTOGRAPHIC INFORMATION,AND COMPUTERS

Abstract

Accessibility is frequently used in transportation planning to measure the efficiency of new infrastructure in terms of travel time and population served. In this article, the authors apply accessibility concepts based on the geo-historical angle. The aim of this study is to investigate the relationships between population dynamics and the railway expansion from 1830 to 1930. Their approach considers a local scale composed of some 36,000 French communes for the demographic data and more than 28,000 kilometers for the railway network. The methodological framework of this database is based on historical geographic information systems completed by anamorphosis analysis. In this way, they are able to map the changing contours of accessibility from the local to the regional and national scales for historical time.     

Identifying Functional Urban Areas in Ecuador Using a Varying Travel Time Approach

Identifying integrated urban areas is an important issue for urban analysis and policy evaluation. In this article, we provide a set of FUAs suitable for monitoring urbanization in Ecuador, a less developed country without commuting data. We do so substituting such socioeconomic flows by available information on road structure, which allow us to work with accessibility based on a varying travel time. In order to build Ecuadorean FUAs, we calibrate our methodology considering Colombian data. We perform several sensitivity analysis and robustness checks to Ecuador with alternative sources of socioeconomic flows. We conclude that the use of GIS data and the calibrated thresholds provide a set of FUAs similar to the ones that would result of using commuting information.     

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.     

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.     

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.     

海口城市建成环境对高峰期网约车通勤出行的影响——基于滴滴出行数据

网约车的普及重塑了居民的通勤行为。城市建成环境作为居民通勤出行的制约因素,是交通地理学的重要研究议题。采用海口市滴滴出行订单数据,刻画格网尺度的居民通勤时间与通勤距离的空间分异格局,并运用地理探测器分析城市建成环境对居民通勤出行的影响。结果表明：(1)早晚高峰通勤时间在空间上表现为中间集聚、四周分散的分布特征;早晚高峰通勤距离呈现梯度递增的圈层结构。(2)不同维度的建成环境因素对通勤时间和通勤距离的影响程度不一;其中距公交站距离、距市中心距离、职住比、道路邻近度是核心影响因素;人口密度、就业可达性、路网密度产生较为显著的影响。(3)从影响效应看,交通区位优越、职住趋于平衡、道路邻近度高、就业可达性好能引导网约车与多元交通协同发展。结果可为改善交通出行环境、优化居民通勤结构提供借鉴。     

Empirical Analysis of a Travel-Time Forecasting Model

The purpose of this article is to analyze empirically a travel-time forecasting model that estimates link travel times on congested road networks. In separate studies by You and Kim, a nonparametric regression model has been developed as a core forecasting algorithm to reduce computation time and increase forecasting accuracy. In this article, the sensitivity of model parameters is evaluated so that the proposed travel-time forecasting model could be utilized in transportation information and management systems such as location-based services and intelligent transportation systems applications.     

Problematizing ‘Knowledge‐for‐Development’

This article argues that measures designed to improve the availability and accessibility of information as a key strategy to facilitate development have become ends in themselves, de‐linked from their potential to have an impact on Southern knowledge systems that may lead to improved development outcomes. The production and dissemination of ever‐greater volumes of information in response to concerns about the uneven availability of information, particularly for individuals and intermediaries based in the global South, are unable to address the persistent problem of the fragmentation of knowledge systems that result from knowledge for development (K4D) initiatives in which information and knowledge are treated as isolated entities. The article presents the findings of a study into the K4D practices of a network of women/gender information intermediaries. It reveals that attempts to strengthen Southern knowledge systems are forestalled by efforts that merely improve the supply of information rather than engaging with knowledge processes in their entirety, thus limiting their potential to promote improved development outcomes. Proxy measures of success are used that fail to challenge the typically neoliberal underpinnings of the dominant knowledge infrastructure. The author concludes that, if knowledge‐based development interventions are to be made more effective, K4D stakeholders need to find ways to engage not just with the supply but with the demand for information, as part of broader efforts to strengthen entire knowledge systems in ways that take account of concerns around hegemony.     

交通投资与经济发展的关系及其区域效应评价方法研究

交通投资与经济发展的内在关系一直没有公认的结论。大家普遍同意交通条件是经济发展的重要支撑要素之一。交通投资只有在生产条件充足的情况下,才会促进经济发展。但交通投资并不是越多越好,而是必须与生产投资保持适当比例。交通投资对交通条件改善的区域影响较为复杂,不同的范围有不同的影响。通达性是目前进行交通网络影响评价最为常用的手段。通达性指标有时间通达性、经济潜能和日通达性。不同的通达性指标从不同的角度对交通网络区域效应进行评价。本旨在对我国主要交通设施区域影响的评价研究起抛砖引玉的作用。