首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 401 毫秒
1.
Measuring the Structure of Road Networks   总被引:8,自引:0,他引:8  
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.  相似文献   

2.
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.  相似文献   

3.
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.  相似文献   

4.
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.  相似文献   

5.
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.  相似文献   

6.
This paper presents four ‘knowledge maps’ or ‘schemes’ which can be used as aids to knowledge management in spatial planning. The schemes relate to the four dimensions of knowledge, i.e. content, sources, application and methods. The schemes are based upon theoretical considerations as well as on practical experience with knowledge management for planning projects, some examples of which are given. They are, furthermore, tested in various ways as to their usefulness. Their primary purpose is, in fact, to make aspects of knowledge management which in practice are often applied in an intuitive manner more explicit, and thus to enhance their reliability.  相似文献   

7.
石飞  朱乐  原榕 《人文地理》2022,37(6):20
公共交通可达性拥有空间属性、时间属性、社会属性和经济属性,它是一种衡量区位价值的综合性指标,不仅可以反映城市空间特征,同时对城市中生活的人的社会经济属性和生活习惯,具有一定的解释力。为了不断适应新形势下的交通发展要求,减少环境负担,早日实现低碳绿色发展,创新公交都市规划与分析方法迫在眉睫。本文对基于个人的、基于效用的、基于基础设施的和基于位置的可达性研究进行了回顾,并归纳了七种公共交通可达性的分析方法,分别为:基于缓冲区的公共交通站点可达性、基于供需模型的公共交通面状可达性、基于网络分析法的公共交通网络可达性、基于成本栅格法的公共交通可达性、基于成本栅格与网络分析的集成法的公共交通可达性、基于高性能图形数据库的公共交通高精度可达性、基于开放地图 API 的公共交通高精度可达性。 以期为我国未来公共交通可达性的分析方法提供指引和借鉴。  相似文献   

8.
Accessibility, measuring the ease of reaching potential destinations, is increasingly being considered as an effective indicator to evaluate the performance of transport and land use interactions. Primal accessibility, a generalization of the first accessibility formulation proposed by Hansen, has been widely used in many studies and demonstrated to be a reliable tool for project, program, and policy evaluation. The dual of accessibility, measuring the time required to reach a given number of opportunities, is less often considered but can be used for optimization in location covering-type problems. This article, hence, clarifies the definitions of primal and dual access, and applies both measures to the Minneapolis—St. Paul metropolitan area for auto and transit to demonstrate their practicality as a metropolitan-level measurement. We explore the correlations and differences between the primal and dual access to better understand the relative strengths of the measures. It is found that, as with primal accessibility, dual accessibility is an efficient approach to evaluate accessibility, which is straightforward to calculate and to explain to policy-makers and the public.  相似文献   

9.
Abstract

The energy policy in Germany encourages an ever-greater utilization of biomass to produce biogas. But this utilization interferes on the natural resources and affects new conflicts regarding other forms of land use particularly flood prevention measures, drinking water supply and recreation. A forward-looking planning is needed to minimize these conflicts. Hence, this paper aims to derive quality and protection standards, summarized in checklists, assessing the effectiveness of different planning instruments with respect to the impact of biogas production in practice. These checklists were used in four model districts in Lower Saxony to evaluate the effectiveness of planning instruments on the regional level. The results show that the investigated Regional Planning Programmes do not contain any explicit planning statements as to the production of biomass or biogas. Specific regulations regarding potential conflict situations are mainly to be found in the respective Protected Area Regulations. However, generally the German spatial planning and sectoral planning provide options to control the production of biogas in a way that it is compatible with the majority of competing land uses.  相似文献   

10.
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。  相似文献   

11.
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.  相似文献   

12.
ABSTRACT This study provides an empirical evaluation of employment accessibility as a determinant of urban land price. We find that the monocentric model, despite recent criticism, can perform satisfyingly if the hedonic value of land is identified in an account of structural and neighborhood characteristics. Gravity employment accessibility measures, however, can explain the residential land gradient entirely and disentangle positive accessibility effects from negative congestion effects related to transport infrastructure. They can therefore be recommended as an appropriate mean to account for labor market accessibility in an environment of dispersed employment, at least if the transport geography is accounted for.  相似文献   

13.
The metropolitan urbanization shows evidence that planning at the regional, subregional and municipal levels with its wide range of territorial, urban and sectorial competences is now longer able to significantly influence territorial development. This has led to a greater demand for alternative approaches, methods and instruments. For this research study, the metropolitan area of Granada was used as a field laboratory to assess the capacity of metropolitan planning to have an impact on metropolitan processes and dynamics. For this purpose, a method for metropolitan planning evaluation, MPE methodology, was proposed, which involves two evaluation processes. This method first evaluated the coherence of plans of different competences and at different scales within the metropolitan context (trans-scalar evaluation); it then evaluated the interaction between methods and proposals in plans and metropolitan dynamics (interactive evaluation).  相似文献   

14.
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。  相似文献   

15.
The assessment of the performance of planning is debated. The evaluation of the conformance of a given national planning system with a set of principles is similarly received with critical and favourable remarks. A relevant case study consists of the conformance of European landscape planning practice with the principles of the European Landscape Convention (ELC). Italy incorporated in 2004 the principles of the ELC with the Code on Cultural Assets and Landscape (CL), which opened the way for new laws, tools, observatories and atlases. The aim of this article is to demonstrate the usefulness of an assessment exercise concerning the conformance with the ELC of planning practice in Italy. We scrutinize planning systems and tools established by peripheral administrations, according to a qualitative and comparative framework. We refine our analysis by focusing on 10 most recent cases and identifying critical issues in current landscape planning practice. The results are promising and show that landscape planning in Italy is increasingly in line with the ELC.  相似文献   

16.
医院可达性评价与规划——以江苏省仪征市为例   总被引:5,自引:0,他引:5  
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。  相似文献   

17.
Using qualitative research methodologies for pedagogic research can provide informative insights into student experiences of the teaching and learning environment in Higher Education. This paper considers the practicalities of undertaking a pedagogic study using focus groups by outlining strategies for effective focus group organization, highlighting good practice from the social sciences and pedagogic literature and providing a critique of a recent geographical study, in which focus groups were used as the sole research method. Furthermore, the paper illustrates how a pedagogic research study can be used to enhance teaching and learning and to inform curriculum planning and course management.  相似文献   

18.
This paper describes a protocol for quantification of heritage copper alloys by energy‐dispersive X‐ray fluorescence spectroscopy (ED‐XRF). The protocol, nicknamed CHARMed PyMca, is designed for users who wish to maximize inter‐laboratory reproducibility of quantitative ED‐XRF results for the wide range of copper alloys found in heritage materials. By maximizing reproducibility, this protocol should facilitate collaboration and allow the rigorous use of shared data and databases. The protocol uses free, open‐source, fundamental parameters software called PyMca. PyMca allows for a consistent and transparent application of the fundamental parameters approach independent of the ED‐XRF instrumentation used. The proposed protocol calls for calibration of standardless PyMca results against a set of certified reference materials designed specifically for use with heritage copper alloys, the so‐called copper CHARM set. Finally, this protocol calls for the calibration‐to‐standards to be carried out following a consistent strategy, including error modelling and the incorporation of a validation procedure. A reproducibility study was conducted using CHARMed PyMca and eight different ED‐XRF instruments of six different types. In comparison to a 2010 study conducted according to the same method, CHARMed PyMca showed a dramatic improvement in reproducibility and method sensitivity.  相似文献   

19.
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.  相似文献   

20.
This paper aims to highlight the problems and possibilities for improving the nature protection zoning of protected areas (PA) in spatial planning. It analyses and compares the systems of spatial planning and the legal basis for protecting nature in PAs in selected EU countries and Serbia. It investigates and compares the role of nature protection zoning and the practice of spatial planning for selected European countries. The case study of a national park in each of the selected countries is used to analyse the nature protection zoning and its role in the coordination of spatial planning for PAs and their surroundings. The initial hypothesis is tested and confirmed that, regardless of differences in the planning systems of the selected European countries, the models of nature protection zoning established for PAs are defining for the coordination of planning instruments in achieving the protection and sustainable development of PAs. The lessons learnt concern the identification of similarities and differences in approaches to nature protection zoning, and their relationship with the spatial planning for PAs in six European countries. Based on these lessons and existing research, recommendations are given for improving the legal basis for the nature protection zoning and spatial planning of PAs in Serbia.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号