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.     

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.     

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.     

年龄分层视角下医疗设施可达性对居民就医行为的影响——以上海市崇明岛为例

年龄是影响就医行为的重要因素,从年龄分层视角出发探讨医疗资源可达性对就医行为的影响有助于理解居民的就医行为决策机理.本文以崇明岛为案例,利用一手调查数据,结合两步移动搜寻算法和回归分析方法,探讨了医疗设施可达性对居民就医机构选择和惯常就医距离的影响,揭示了不同年龄群体之间就医行为影响机理的差异.研究发现,医疗设施可达性...     

A Factorial Model of Aggregate Spatio-Temporal Behavior: Application to the Diurnal Cycle

The cross-sectional nature of much social data, coupled with the static view provided by maps and current spatial data handling software, have produced a tradition of research on urban spatial structure that is largely two-dimensional and derived from residential locations. The paper presents an analysis of a space-time diary data set collected in Halifax, Nova Scotia. A series of transformations are used to convert the individual diary records to a three-mode matrix of intensities, which is then analyzed using the PARAFAC three-mode factor model. Home/work is found to be the strongest organizing dimension of the urban space-time, followed by entertainment, shopping, and education / work. We show how these dimensions appear to varying degrees in different locations, time periods, and human activities. The paper argues for a dynamic view of urban spatial structure in which only the physical facilities remain static.     

基于交通网络中心性的长春市大型综合医院空间可达性研究

交通网络中心性是测度交通网络及社会经济活动可达性的有效手段。从交通网络中心性视角,结合可达时间研究长春市中心城区大型综合医院空间可达性。大型综合医院邻近度和中间性与距离(到人民广场路网距离)均呈负相关,在距人民广场最近处二者大致相等且最高,随着距离的增加,邻近度超过中间性。距人民广场4740-5799米处中间性超过邻近度并形成高值分布区,7862-8400米处二者均降到最低。约33.3%的大型综合医院空间可达性最好,其集中分布于以人民广场为中心的城市中心。空间可达性最差的大型综合医院约占总数的24.1%,多分布于城市边缘。空间可达性较差的大型综合医院为数不多,且多分布于城市周边。但高邻近度、高中间性、可达时间较长的大型综合医院主要分布于安达街沿线。高邻近度、低中间性,可达时间较短的大型综合医院则多分布于火车站前与新民大街沿线等城市中心位置。     

北京市就业者日常活动的时间利用研究——基于2007年与2017年调研数据的对比

时间利用作为了解人类活动与生活安排的重要维度,与居民的生活质量息息相关.以往的时间利用研究从个体行为的角度透视了城市化过程带来的影响,然而少有利用交叉数据在不同年份对居民的时间利用模式进行直接的比较研究.本文基于2007年和2017年在北京进行的两次活动—出行日志调查数据,采用描述性统计、空间分析、回归分析等方法探讨了...     

Spatial accessibility and equity of playgrounds in Edmonton, Canada

Assessing spatial equity with respect to urban public amenity provision involves examining the association between amenity distribution and population need for amenities. Geographic Information Systems in coordination with local spatial autocorrelation, were used to investigate the association between neighbourhood accessibility to playgrounds and demographic and social need for playgrounds in Edmonton, while considering differences in playground quality throughout the city. The primary objectives of this study were to assess whether playground provision, for location and quality, in Edmonton is equitable and, more generally, to investigate the role that amenity quality plays in assessing spatial equity. The results indicate that playgrounds are equitably distributed within Edmonton, with the highest-social-need neighbourhoods having the greatest accessibility to playgrounds. However, once differences in playground quality are considered, there is less of an association between high-social-need and high-accessibility areas. The findings suggest that greater attention be paid to differences in playground quality within Edmonton and that spatial equity researchers give greater consideration to amenity quality when evaluating spatial equity within cities.     

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.     

基于POI的城市影子教育机构空间格局及其影响因素——以兰州市主城区为例

影子教育作为普遍而又特殊的人文社会现象尚未引起空间科学的关注。本文基于POI数据,融合GIS空间分析及地理探测器等方法,探究了兰州市影子教育机构空间分布特征及影响因素。结果表明：①兰州市影子教育机构总体表现出“西疏东密”的河谷带状分布,并呈现“一主多次”的组团式空间结构;②内部差异较大且不同类型机构的分布特征不同,区位选择的尺度差异明显且集聚形态各异;③不同类型机构的专业化水平差异显著,形成了不同功能型的专业化空间单元;④城市居住小区、商服环境、主流教育机构及交通可达性是影响影子教育空间布局的重要因素,由此驱动形成了不同类型的空间布局模式。     

广东区域可达性综合探测及空间分异特征研究

本文以广东省陆路交通网络为对象,综合利用可达性度量模型对广东省区域可达性进行测算和空间特征分析,并进一步实现广东省省域的等级分区。结果表明,广东区域日可达性和时间可达性呈现出同心圆分布特征,并具有明显交通网络指向性;但在空间、交通网络结构和社会经济等因素的综合影响下,潜力可达性表现出多中心圈层的空间分异特征。研究揭示了广东省区域可达性的空间格局及分异规律,探讨了地理区位和城市发展在可达性空间分异中作用,从而为广东产业布局优化、土地集约化利用以及区域协调发展提供科学参考。     

基于县域尺度的江苏省乡村性空间格局演变及其机理研究

基于区域城乡一体的思想构建乡村性指数RI,通过GIS-ESDA空间分析框架,运用空间自相关、空间变差函数等测度模型对20世纪90年代以来县域尺度江苏省乡村性空间格局演变和机理进行了研究。结果表明:1990年以来县域尺度江苏省乡村性表现出较强的空间自相关性,相似地区在空间聚集分布,且集聚的程度不断增强;乡村性热点区空间结构主要以徐州-宿迁-淮安为核心的圈层结构,并且不断向盐城集聚,呈现出明显的地理集中演变特征;县域尺度乡村性空间格局的连续性和自组织性越来越强,由空间自相关引起的结构化分异的机理越来越显著;东北-西南方向乡村性空间差异较小,东南-西北方向乡村性的异质性则十分明显,空间差异较大。     

线上和线下生活服务设施可达性及其协调关系——以生鲜果蔬店铺为例

作为智慧城市的重要组成部分,“新零售”得到蓬勃发展,提供当日配送服务的“新零售”深刻影响了城市生活服务的可获取性和时空可达性。本文以南京中心城区为例,运用两步移动搜索法、耦合协调度模型等方法,探究提供当日配送生鲜果蔬服务的店铺和传统生鲜果蔬实体店空间分布特征,分析线上和线下生鲜果蔬店铺的可达性及空间协调关系。研究发现,线上生活服务遵循技术扩散假说,强化了中心城区的生活服务集聚,同时线上生活服务集聚和可达性仍受实体地理空间约束;线上生活服务有悖于效率假说,对传统生活服务的空间分异具有加强作用,整体上没有提高生活服务的供给效率和空间公平性。研究结果可为新零售影响下城市生活服务设施的配置优化提供科学依据。     

Infrastructure and Growth in a Spatial Framework: Evidence from the EU regions

This paper examines the return to infrastructure in the European Union regions in a spatial framework. It innovates on the earlier literature on infrastructure and growth by a combination of regional focus, disaggregation of infrastructure types and consideration of spatial dependence. Different types of infrastructure capital are considered as determinants of economic performance at the Nomenclature des Unités Territoriales Statistiques level. To account for growth spillovers among regions, a spatial Durbin model is estimated. The results confirm the important role of infrastructure and identify the highest rates of return as associated with telecommunication, quality and accessibility of transportation networks, with a positive impact of roads and railways.     

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.     

Measuring Regional Cohesion Effects of Large-scale Transport Infrastructure Investments: An Accessibility Approach

Transport infrastructure is considered one of the main policy instruments to achieve the cohesion goal, although the inclusion of cohesion effects in assessment methodologies is scarce and uneven. Although most cohesion studies are constrained to the analysis of regional disparities in economic indicators, this approach can be broadened to include other regional performance indicators. One of these indicators could be accessibility measures, from the point of view that accessibility, representing a competitive advantage of locations, constitutes a “desirable good” closely related to the welfare of each region. This paper suggests using changes in the spatial distribution of accessibility as a proxy to assess regional cohesion effects of transport infrastructure investments. However, as the conclusions taken depend heavily on the formulation of the accessibility measure, we recommend computing a set of accessibility indicators and analysing their results in a complementary way. The proposed methodology is tested by assessing regional cohesion effects of the large-scale road and rail transport infrastructure investments carried out in Spain in the period 1992–2004. The results obtained show that cohesion has improved for the road mode, while regional disparities have increased for the rail mode. This paper identifies the main factors driving this final cohesion effect and explores the strengths and weaknesses of the different accessibility indicators that were considered. The approach suggested in this paper has the potential to be applied in transport planning processes, and may eventually complement existing strategic assessment methodologies.     

移动搜索法在教育公共服务可达性评价中的改进与应用——以福州城区幼儿园为例

采用可变步长的两步移动搜索法,以福建省福州市为典型案例,以居民点（普查小区）为分析单元,对各居民点入园空间可达性进行了测算,并与传统的两步移动搜索法进行对比分析,综合判别学前教育资源空间分布特点。研究表明：福州城区入园可达性总体情况并不理想,仅有少数地区、少量人群可以获得较好的幼儿园空间的可达性。入园可达性在地理空间上呈现出多中心结构,高可达性地区主要分布在市中心并在城市周围零星分布,边缘乡镇特别是除西部以外的乡镇地区缺教明显,入园可达性在城区内部差异较大,幼儿园资源过剩地区和稀缺地区呈两极分化的格局。可变步长的两步移动搜索法能更为客观有效地对幼儿园的布局状况进行评价。而传统方法有一定的夸大作用,且降低了内部的差异,在一定程度上掩饰了幼儿园资源分布的不公平现象。     

基于加权平均旅行时间的浙江省交通可达性时空格局研究

以浙江省69个县(市)为研究对象,利用1996、2004、2012年路网数据,借助ArcGIS网络分析功能,采用基于城镇综合发展水平的加权平均旅行时间指标,探讨浙江省综合交通网络中节点城镇可达性及其时空演变特征。研究结果表明:①1996-2012年,各城镇可达性均出现不同程度提高,彼此间联系趋于紧密;②城镇可达性存在空间分异,且提升幅度各异,均衡化趋势明显;③城镇可达性空间格局变化大,逐渐向以"四大都市区"为中心向四周递增的"∏型"多级空间结构转变。总体上来看,城镇可达性变化及空间格局演变体现了区域统筹发展的战略要求。