A New Algorithm for Graph-theoretic Nodal Accessibility Measurement

Accessibility is a useful concept in the study of the spatial structure of a region, if it can be calibrated appropriately. While graph-theoretic analysis has been used widely as a measurement scheme for the nodal accessibility in various transport networks, several limitations have been pointed out in the existing graph-theoretic accessibility measurements. This study proposes a new algorithm for deriving the nodal accessibility measure, as an attempt to improve the conventional graph-theoretic accessibility measurements. Corrections are made in such a way that irrelevant loops are excluded and relevant indirect connection paths are included selectively. In particular, the new algorithm is developed for intraurban subway networks, and includes the characteristics of intraurban subway traffic behavior. The concept of inconvenience of transfer is introduced, which is one of the most influential factors in the intraurban subway traffic. Nodal differentiation is allowed, if the nodes play different roles in the travel behavior and eventually in the accessibility. For this purpose, we employ a weighting procedure, according to which the influence of transfer on a sequence of linkages is taken into account. The new accessibility measurement scheme is then applied to the Seoul subway network. Here GIS techniques are utilized to generate accessibility surfaces from the discrete nodal accessibility values, and the changes in the spatial structure of the nodal accessibility are analyzed. Finally, based on the resulting changes in the spatial structure of accessibility in the subway network, the direction of changes in the land value and the land use pattern in Seoul is discussed.     

公共服务设施可达性、个人社会资本与居民心理健康——基于北京的实证研究

利用2018年来自北京的问卷调查数据,本文探讨了公共服务设施可达性、个人社会资本及其交互作用对居民心理健康的影响。研究发现：公共服务设施可达性对心理健康具有显著的正向影响,且对新市民的影响更突出。个人社会资本中密切交往的网络规模、从社会网络中获取经济支持两个维度对其心理健康有显著正向作用,但在新市民和本地市民群体间不存在显著差异。个人社会资本能够强化公共服务设施可达性对心理健康的正向影响。本文验证了社会生态学的健康促进模型的相关假设,即外部环境特征和个人社会资本相互嵌套共同影响个人健康水平。鉴于此,健康城市规划需兼顾“硬件”与“软件”层面,既要构建公平正义的空间环境,还需加强社会资本和社会组织培育。     

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.     

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.     

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.     

Multiple Allocation Hub Location Model with Fixed Arc Costs

This article formulates a model to analyze the role of fixed costs in the design of optimal transportation hub networks. The primary purpose of this article is to better model costs in hub networks, an issue that has attracted considerable attention. This article allows particular versions of hub networks to emerge from the cost structure, rather than by imposing a rigid predefined connectivity protocol. The article integrates modeling approaches from an environmental hub location model with the three‐index formulation of Ernst and Krishnamoorthy to produce a hub location model with fixed and variable costs for all arcs. Our goal is to demonstrate how the inclusion of a richer cost model in transportation hub location can generate a wide range of different network types, depending on the relative magnitudes of the cost elements. While the existence of special case network solutions is well known and has been exploited in optimization, the current research provides added insight to the cost of flow in a more, or less, connected hub network. Eight fundamental prototype networks are derived as special cases, and some additional unanticipated network types also emerge. The results are illustrated with a standard CAB25 data set.     

A Combined Cluster and Interaction Model: The Hierarchical Assignment Problem

This article presents a new spatial modeling approach that deals with interactions between individual geographic entities. The developed model represents a generalization of the transportation problem and the classical assignment problem and is termed the hierarchical assignment problem (HAP). The HAP optimizes the spatial flow pattern between individual origin and destination locations, given that some grouping, or aggregation of individual origins and destinations is permitted to occur. The level of aggregation is user specified, and the aggregation step is endogenous to the model itself. This allows for the direct accounting of aggregation costs in pursuit of optimal problem solutions. The HAP is formulated and solved with several sample data sets using commercial optimization software. Trials illustrate how HAP solutions respond to changes in levels of aggregation, as well as reveal the diverse network designs and allocation schemes obtainable with the HAP. Connections between the HAP and the literature on the p-median problem, cluster analysis, and hub-and-spoke networks are discussed and suggestions for future research are made.     

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.     

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...     

A Comparison of Simple Lattice Transport Networks for a Uniform Plain

The objective is to compare construction and transport costs for triangular, orthogonal, and hexagonal regular lattices as transport networks serving a uniform, unbounded plain. The lattices are standardized so that the average distance from the elementary area to the edge is the same for each. This standardization results in equal construction costs for the three networks; thus, the comparison can be made in terms of route factors, which favors the triangular lattice over the other two.     

From infrastructure to digital networks: accessibility and connectivity in transport geography research at Aberdeen

ABSTRACT

This paper considers the contribution made to transport geography research at the University of Aberdeen over the last century. In section one, the earliest work in transport geography emphasised the physical connectivity provided by transport through infrastructure networks. Section 2 discusses the contribution made at Aberdeen to debates around accessibility and connectivity. This work had a strong rural dimension and evidenced a growing recognition of the importance of technology in transport. It provided the springboard for research on digital connectivity with important contributions to the wider domain of transport studies in the fields of flexible transport, rural connectivity, transport and energy and social media and big data as reported in Section 3. Section 4 brings the story of transport research at Aberdeen up to the present. It frames research under the banner of intelligent mobility (IM), which links technology and mobility to the wider societal objective of enabling the smarter, greener and more efficient movement of people and goods. Contributions are reported to the fields of shared mobility, smart rural mobility, transport security and privacy and accessibility. Finally, a return to the theme of infrastructure networks and connectivity is highlighted in work on global production networks in aviation.     

Measuring the Structure of Road Networks

Spatial networks display both topologic and geometric variations in their structure. This study investigates the measurement of a road network structure. Existing measures of heterogeneity, connectivity, accessibility, and interconnectivity are reviewed and three supplemental measures are proposed, including measures of entropy, connection patterns, and continuity. The proposed measures were applied to 16 test networks, which were derived from four idealized base networks: 90°, 45°, 30°, and completely connected. The results show that the differentiated structures of road networks can be evaluated by the measure of entropy; predefined connection patterns of arterial roads can be identified and quantified by the measures of ringness, webness, beltness, circuitness, and treeness. A measure of continuity evaluates the quality of a network from the perspective of travelers. Proposed measures could be used to describe the structural attributes of complicated road networks quantitatively, to compare different network structures, and to explore the structural evolution of networks in the spatial and temporal context. These measures can find application in urban planning and transportation practice.     

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.     

NETWORK LOADING VERSUS EQUILIBRIUM ESTIMATION OF THE STOCHASTIC ROUTE CHOICE MODEL MAXIMUM LIKELIHOOD AND LEAST SQUARES REVISITED*

Daganzo (1977, 1979), Daganzo and Sheffi (1977), Sheffi (1985), and Sheffi and Daganzo (1980) have used one assumption about traveler behavior in developing estimation techniques for the stochastic route-choice problem and another assumption in predicting flows on networks by using the same model. In estimation, they calculate the congested travel costs of the network links from observed flows on the network, and the network is loaded based on these costs. In prediction, they follow their stochastic user-equilibrium assumption by which travelers evaluate costs using the mean of the observed flows (or equilibrium flows). The travel-cost coefficient obtained from the loading method systematically overestimates the true travel-cost coefficient from which the observed flow data (which must be used in loading) is generated. The estimates of the same coefficient, obtained in this paper, by constraining the estimation results to conform to the equilibrium conditions are unbiased, and only marginally less efficient (have larger standard deviations). The average percentage error and inefficiency of the link flow predictions based on the loading method increases as the level of congestion on the network rises. In contrast, the average percentage error of link flow predictions based on the equilibrium estimation method declines and their efficiency remains very high as the level of congestion on the network rises.     

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.     

基于高斯两步移动搜索法的沈阳市就业可达性评价

将高斯两步移动搜索方法引入到就业可达性测度研究中,在证明方法有效性的同时,也对研究案例沈阳市中心城区的就业可达性空间格局、形成机理进行了分析,并提出相应的调控策略。结果显示,沈阳市中心城区的就业可达性在空间上并非均匀分布,而是呈现为明显的中心-外围格局。形成这一格局的机理有:①单中心的城市形态;②城市规划的功能性布局;③居住的郊区化;④旧城改造与政策性住房;⑤地理要素的空间阻隔。提出用足规划手段促进产业与人口均衡化布局、旧城改造与政策性住房的合理落位、完善城市交通,破除路径障碍与培育多中心城市空间结构等调控策略。     

基于GIS的农村医疗设施空间可达性分析——以河南省兰考县为例

针对农村医疗设施空间分布的公平性问题,提出了使用GIS技术和空间可达性指标评估医疗设施的区域分布特征。以兰考县乡级以上卫生院为例,建立人口分布、医疗设施位置、行政区域等地理数据库,选择人均医疗资源分配、就医的最近距离、选择医院的机会、重力模型及改进的重力模型5个空间可达性模型,计算了各乡镇、各行政村的医疗设施可达性指标,并制作了相应的专题地图;在此基础上对医疗设施的空间布局进行了分析。空间可达性指标全面地反映医疗设施的空间分布特征,鉴别出资源分配较薄弱的区位,是农村医疗改革中设施规划和资源分配的重要依据。     

乡村地区公路网通达性水平研究——以广东省连州市12乡镇为例

以广东省连州市为例,设计路网连通度、可达性、农村路网与干线路网衔接的平均距离三项指标来分析乡村地区公路网的通达性水平。结果显示,连州市路网的连通度较低,布局不完善,并存在明显的干线路网指向性特征;路网可达性水平总体不高,各乡镇内部联系的便捷度普遍较低,且呈现出同心圈层的结构;农村路网与干线路网的衔接较好,具有较强的集散功能。最后,通过计算指综合分值的方法,对连州市的农村路网通达性空间格局进行分析,根据综合得分将连州市12个乡镇分为5个等级,其中连州镇、东陂镇的通达性水平最高,通达性水平最低的是三水瑶族乡;并初步探讨了其背后的形成机理,认为农村路网的通达性水平是多种因素综合作用的结果,包括区域面积、地形状况、经济实力、结点布局、道路建设等。     

Designing a socially efficient cultural policy: the case of municipal theaters in Warsaw

While public support for culture has become a less self-evident privilege than in the past, the economic evidence for benefits a society gains from these goods has become essential for both cultural economics and cultural policy. The aim of our study is to investigate socially preferred ways of allocating scarce public resources among municipal theaters in Warsaw. The problem investigated is a current issue for local policy-making, but in a broader sense, it illustrates how state-of-the-art stated preference methods can be employed to support cultural policy. We find that inhabitants of Warsaw assign a positive value to the broader accessibility of the theaters, and their willingness to pay for making them a truly public good (by introducing a program of highly discounted tickets) exceeds the costs of such a policy. However, we also find that the cost-benefit relationship varies across theaters with different types of plays in their repertories. Our results imply a different level of socially efficient support for experimental, drama, children’s and entertainment theaters.     

Rethinking Remoteness: A Simple and Objective Approach

This paper re‐examines the characteristics and assumptions of current remoteness/accessibility classifications in Australia and proposes a simple and easily understandable alternative measure for remoteness. In this study, remoteness is redefined simply as the average distance between two nearest people within an appropriate spatial unit where population distribution is assumed to be homogenous. By definition, the most straightforward remoteness and incapacity index (RII) would be remoteness times a measure of the incapacity for social and commercial interaction, where remoteness is gauged by the square root of the area divided by the population, and incapacity is measured by the reciprocal of population. Australian Bureau of Statistics Statistical Local Area (SLA) level population data and digital boundaries have been utilised for assessment of this index. The utility of the RII is demonstrated with two examples of activity measures for general practitioner services and businesses. At the State/Territory level, RIIs are negatively related to both general practitioner services per person (Pearson correlation coefficient r=?0.873), and the number of businesses per person (r=?0.546). The correlation can be further enhanced by normalising the distributions of the remoteness scores with a simple logarithmic function. The strong correlations confirm that remoteness has a substantial inverse impact on daily activities. Greater distance means longer time and higher costs for travelling, diseconomy of scale, and higher personnel costs. The RII provides an alternative measure of remoteness that is both intuitive and statistically straightforward and, at an SLA level, closely coincides with the commonly used but complex Accessibility/Remoteness Index of Australia Plus (ARIA+). Significantly, the RII is free of the service specific and policy sensitive adjustments justified by accessibility that have been introduced into existing measures.