Road Network Accessibility Research Articles

ACCESSIBILITY ASSESSMENT OF EMERGENCY VEHICLES IN TOKYO METROPOLITAN AREA AFTER A LARGE EARTHQUAKE

Abstract. At the time of a large earthquake, property collapse (e.g., building collapse and street blockage) will obstruct emergency activities (e.g., firefighting activity and ambulance service) and cause the expansion of secondary damage. For reducing the secondary damage of a large earthquake, it is important to assess the accessibility of emergency activity under property collapse. However, the accessibility index, which can evaluate the emergency activity considering the effect of property collapse, is not developed nor applied in actual urban area. In this paper, we propose the street network accessibility: indices of assessing the movement of emergency vehicles. Then, we construct a simulation model that describes property collapse and the movement of emergency vehicles. Performing the simulation in Tokyo Metropolitan Area, we evaluate the damage of each building/street and assess the street network accessibility after a large earthquake. Finally, analysing the relationships among indices, we indicate that it is important to evaluate the street network accessibility from multiple viewpoints.

Assessment of Street Network Accessibility in Tokyo Metropolitan Area After a Large Earthquake

It is difficult to evaluate the street network accessibility after a large earthquake occurs. In this paper, we construct a model to evaluate the street network accessibility for wide-area emergency behaviors under the condition of property damage in the Tokyo Metropolitan Area after a large earthquake. Additionally, we analyze the relationships between a local environment and street network accessibility by using multiple regression analysis. Finally, we discuss some important factors for evaluating risk mitigation strategies.

Improving post-disaster road network accessibility by strengthening links against failures

We study a network improvement problem to increase the resilience of a transportation network against disasters. This involves optimizing pre-disaster investment decisions to strengthen the links of the network structurally. The goal is to improve the expected post-disaster accessibility. We first propose a new dependency model for random link failures to predict the post-disaster status of the network. We show that the probability of any network realization can be computed using a Bayesian network representation of the dependency model. As the computational effort grows with the network size, we use our proposed dependency model in a network sampling algorithm. We then estimate an accessibility measure, namely, the expected weighted average distance between supply and demand points by checking pre-generated short and dissimilar paths in the sample. We minimize this measure and decide on the links that should be strengthened in a two-stage stochastic programming framework. As the failure probability of a strengthened link decreases, the discrete scenario probabilities depend on the first-stage decisions. To tackle this challenge, we develop an efficient tabu search algorithm. We apply our methods to a case study of Istanbul under the risk of an earthquake, both to illustrate the use of the methods and to derive insights for decision makers.

Assessing the implications of the recent community opening policy on the street centrality in China: A GIS-based method and case study

Recently, the Chinese government raised an urban planning policy which suggests communities open their private roads for public transport and establish street networks with high spatial density in cities. In this context, the purpose of this study is to analyze the potential changes to street network accessibility using GIS techniques and to provide spatial information that may influence the decision making of urban managers. In addition to the existing street network data in the case study city, Shenzhen, intra-community roads are extracted from building footprints in GIS topographic database and used to construct a potential street network with respect to the community opening policy. An automatic GIS-based method is proposed here to analyze the location advantage information in the simulated urban environment, by combining Delaunay triangulation model and graph theory concepts. Specifically, we establish a two-step framework based on the spatial relationships between roads and buildings. Firstly, intra-community roads between neighboring building footprints are generated using a Delaunay triangulation skeleton model, and with the existing inter-community roads they form the simulated network. Secondly, street centrality indices of the current and simulated networks are compared in terms of closeness, betweenness and straightness. Results indicate that after applying the policy the global accessibility in the city would be increased at some places and decreased at others, and places' directness among others would be generally improved. In addition, the skeleton of central routes for through traffic would not change much. The presented method can also be applied to other cities.

Accesibilidad y conectividad geográfica en áreas rurales. Caso de la comuna de María Pinto, Chile

En América Latina y especialmente en Chile, las áreas rurales son espacios que todavía presentan brechas de desarrollo en torno a la accesibilidad y la conectividad geográfica del territorio. La geografía puede aportar enfoques conceptuales y metodológicos para superar las brechas espaciales. Este artículo apunta a determinar y categorizar la accesibilidad y conectividad geográfica que tiene la población rural respecto de su centro urbano. Consideramos el estudio de caso como enfoque para analizar este tema, abordando de este modo la situación de la comuna de María Pinto, localizada en la Región Metropolitana de Santiago, Chile. Los objetivos que guían esta investigación son: caracterizar la red vial existente, determinar la conectividad y la accesibilidad geográfica intracomunal y determinar áreas homogéneas de accesibilidad en relación con el centro urbano de la comuna de María Pinto. En la discusión y conclusiones planteamos la relevancia que estos conceptos tienen con la movilidad de la población rural como parte de las políticas de desarrollo.

SPATIAL LINKAGE AND URBAN EXPANSION: AN URBAN AGGLOMERATION VIEW

Abstract. Urban expansion displays different characteristics in each period. From the perspective of the urban agglomeration, studying the spatial and temporal characteristics of urban expansion plays an important role in understanding the complex relationship between urban expansion and network structure of urban agglomeration. We analyze urban expansion in the Yangtze River Delta Urban Agglomeration (YRD) through accessibility to and spatial interaction intensity from core cities as well as accessibility of road network. Results show that: (1) Correlation between urban expansion intensity and spatial indicators such as location and space syntax variables is remarkable and positive, while it decreases after rapid expansion. (2) Urban expansion velocity displays a positive correlation with spatial indicators mentioned above in the first (1980–1990) and second (1990–2000) period. However, it exhibits a negative relationship in the third period (2000–2010), i.e., cities located in the periphery of urban agglomeration developing more quickly. Consequently, the hypothesis of convergence of urban expansion in rapid expansion stage is put forward. (3) Results of Zipf’s law and Gibrat's law show urban expansion in YRD displays a convergent trend in rapid expansion stage, small and medium-sized cities growing faster. This study shows that spatial linkage plays an important but evolving role in urban expansion within the urban agglomeration. In addition, it serves as a reference to the planning of Yangtze River Delta Urban Agglomeration and regulation of urban expansion of other urban agglomerations.

Research of Road Accessibility under Emergency Coupling in Tibet

With the improvement of living conditions and booming tourism in Tibet, more and more people choose Tibet as a tourism destination. More emergency events may happen when lots of people swarm into Tibet. This paper focuses on the accessibility of road network near Jokhang Temple in Lhasa at a peak tourist season with different events coupling. Some data about path lane, path width and trips of road has been collected and accessibility of road near Jokhang Temple has been computed with two disparate events. The result shows different emergencies coupling may cause different consequences to road network. So highway management department can set up various strategies to speed up traffic flow based on the degree of events coupling and make relevant measurements.

A Study on Improvement of Road Ratio Index Consideringthe Accessibility of Road Network

지역 내 또는 지역 간을 이동할 경우에 이용하는 도로는 지역마다 시설 수준이 상이하여 지역별로 차이가 발생한다. 따라서 도로율이라는 지표로 해당 시설의 수준을 간접적으로 파악할 수 있다. 도로율의 개념은 사용하고자 하는 목적에 따라 다소 차이는 있으나, 보통 행정구역 면적당 도로의 총연장으로 산정하고 있다. 그러나 단순히 물리적인 통계자료로만 도로율 지표를 산정함에 따라 도로의 등급 또는 도로의 차로수 차이, 나아가 지역 간 통행에 있어서는 고속도로와의 접근성 등 전반적으로 도로의 질적 수준인 교통의 처리 능력을 고려하지 못한 채 사용하고 있다. 이에 본 논문에서는 기존 도로율 지표가 갖고 있는 한계점을 극복하기 위하여 통행의 이동을 고려한 도로의 지역 내 및 지역 간 접근성 지표를 각각 산출하고, 이 두 지표의 조합을 통해 최종적으로 도로의 서비스 지표를 구축하였다. 사례 분석은 충청남도의 시 · 군을 대상으로 하였고, 충청남도 시 · 군의 도로 수준을 결정하는 요인을 파악하기 위해 해당 지역의 지역개발정책 및 공공투자사업 업무를 담당하는 지역전문가를 대상으로 설문을 실시하였다. 분석결과 도로의 서비스 지표 순위는 기존 도로율에 따른 순위와는 차이를 보이는 것으로 분석되었다. 면적 대비 도로의 연장이 상대적으로 큰 도시의 경우 통행량이 많아 도로의 서비스 수준은 낮은 것으로 분석되었다. 즉 인프라가 잘 되어 있는 도심지라 하더라도 서비스 지표는 낮게 추정되는 지역이 발생하는 것으로 나타났다. 모형의 적합도에서는 서비스 지표가 도로율에 비해 혼잡지도에 따른 순위와의 차이가 적은 것으로 도출되어 현 도로 수준에 대한 설명력이 보다 높다는 것을 알 수 있다. 본 논문의 결과를 토대로 다소나마 지역낙후도지수 산정을 위한 도로율 지표 순위를 합리적으로 반영할 수 있어 궁극적으로 타당성 판단 시 지역균형발전에 대한 평가를 개선할 수 있을 것으로 기대된다.

Road Network Accessibility and Socio-economic Disadvantage Across Adelaide Metropolitan Area

Transport mobility is important in defining the population’s accessibility to services and facilities. Few studies have investigated the relationship between geographical accessibility of urban services for the population living in residential areas and socio-economic parameters. In this paper, the distribution of residential parcels is analyzed from a rarely explored angle—that is, its location in relation to services and facilities. The aims of this study are first to develop an index of the accessibility of various urban resources to each residential parcel in a metropolitan area of Adelaide using spatial data analysis in Geographical Information Systems and then to develop a relationship with socio-economic and land use attributes of statistical areas using ordinary least squares (OLS) and geographically weighted regression analysis. As expected the ‘Distance to CBD’ variable has a positive relationship with metropolitan Accessibility/Remoteness Index of Adelaide (metro-ARIA) meaning that the farther away statistical areas have lower accessibility to services. In the case of population density variable, the relationship is mostly negative except few areas in the far south, west and northern areas, which showed a positive relationship. When similar results for median family income were studied, in some of the southernmost parts of Adelaide, it showed a strong positive relationship with metro-ARIA. This research will not only provide new insight into spatial differences between metropolitan areas but also potentially help in assessing the impact of the changes in services on land use. The findings of this paper, therefore, have important implications for service provision and social infrastructure investment.

Road network emergency accessibility planning after a major earthquake

In the aftermath of disasters such as major earthquakes, several roads may be blocked by rubble and the population tends to search refugee in certain gathering points of the city. Road network accessibility becomes an important issue for logistic operations, specially on the first days after the quake, when the relief distribution is crucial for survival. This study focused on the Road Emergency Rehabilitation Problem, divided into the Road Network Accessibility Problem (RNAP) and the Work-troops Scheduling Problem (WSP). The first one consists in finding traversable paths for relief teams to reach the population, and the later generates a repairing schedule to improve access to refugee areas. The contributions of this study are two-fold: we present the process of transcribing satellite imagery data into graphs, and mathematical formulations for the RNAP and WSP, along with heuristics to solve the WSP. The proposed methods are able to handle large-scale graphs in an acceptable running time for real scenarios. They are tested on simulated instances and on the graph of Port-au-Prince, with more than 10,000 vertices and edges. The Port-au-Prince graph was generated from satellite images obtained by the International Charter “Space and Major Disasters” a few hours after the 2010 earthquake.

Work-troop scheduling for road network accessibility after a major earthquake

The road network accessibility is an important issue for earthquake relief operations, since several roads may be damaged obstructing the access to certain areas. This work proposes a mathematical model and two heuristics for the road repairing work-troops scheduling in order to increase accessibility to the population as fast as possible after a major earthquake. Solutions for randomly generated instances given by the model are used to evaluate the heuristics' performance. The heuristics are tested on a graph with more than ten thousand vertices and edges from Port-au-Prince 2010 earthquake in Haiti.

Straw effects of new highway construction on local population and employment growth

Growing concern surrounding the existence of ‘straw effects’ is evident in recent studies that reveal how new road network accessibility negatively causes lower economic productivity in lagging areas by increasing the level of local dependency on major metropolitan areas. This paper examined the potential ‘straw effects’ of two new highways, the Central Inland Highway and Seoul–Chuncheon Highway, on regional population and industry growth in Korea using Difference-In-Differences (DID) analysis, including specific analysis of lagged areas of the Central Inland region. The findings revealed that there is no evidence of the ‘straw effects’ and that it is not only the newly built highways that contribute to increasing local population and employment in lagging areas but also existing highway accessibility.

Integrated Co-evolution Model of Land Use and Traffic Network Design

An integrated co-evolution model with the consideration of land use and traffic network design is proposed in this paper. In the suggested model, two kinds of economic agents are considered. On the one hand, the government makes the investment decision for the traffic network improvement based on the current traffic condition under the limited budget. On the other hand, households and companies will choose their locations according to the attraction of each traffic zone related to the road network accessibility and the housing price. Therefore, the land use is indicated by the population and employment distributions through the evolution process. Besides, the improvement of road capacity is modeled by a general bi-level programming of traffic network design. Simulation experiments show that the city will be more efficient and will have higher average accessibility for employment and population in the evolution process.

Road accessibility and articulation of metropolitan spatial structures: the case of Madrid (Spain)

In the last few decades, rapid growth in mobility has facilitated the inclusion of distant places in metropolitan processes and the modification of traditional metropolitan areas into Polycentric Urban Regions. This paper aims to understand the articulation of metropolitan urban regions through a diachronic road network accessibility analysis with a focus on the Madrid Metropolitan Region (Spain) over a period of general increase in accessibility. The findings reveal that the metropolitan core has been reinforced and that its influence area has expanded. However, the main contribution of this work is the proposal of a methodological approach to identify city-profiles among the sub-centres organising the emerging polycentric urban structures.

The Study of the Relationship between Accessibility and Mixed Land Use in Tainan, Taiwan

Mixed land-use is one of the long-term policies to land management in most Asian countries. In the recent, it not only been advocated by new urbanism, but also the important land planning concept of smart growth and compact city in America and many European countries. Land use and transportation both are the important elements for urban and regional development. In the recent, new urbanism promoted mixed land use to be a land developmental type, in the meantime, the concept and importance of Transit-Oriented Development was emphasized. It was mean that mixed land use and transportation need to cooperate to achieve the goal of good urban development. In this paper, in addition to measure the degree of mixed land use, it also provides the new method and concept of accessibility, adopting the spatial accessibility of road network to examine the relationship between transportation system and mixed land-use, to view whether transportation system and mixed land-use can coordinate each other that it contributes to establish strategies for land use, transportation planning and management; on the other hand, the analysis theory and method can be used to explore the structure and patterns of urban development further for other relevant departments reference when establishing the policies.

Urban built environment configuration and psychological distress in older men: Results from the Caerphilly study

BackgroundFew studies have examined the impact of the built environment configuration upon mental health. The study examines the impact of objectively assessed land use and street network configuration upon psychological distress and whether this association is moderated by the natural environment and area-level deprivation.MethodsIn a community sample of 687 older men from the Caerphilly Prospective Study, built environment morphological metrics (morphometrics) were related to differences in psychological distress as measured by the General Health Questionnaire. Cross-sectional data were taken from the most recent (5th) phase. A multi-level analysis with individuals nested within census-defined neighbourhoods was conducted. Environmental measures comprised GIS-constructed land use and street network metrics, slope variability and a satellite derived measure of greenness.ResultsReduced psychological distress was associated with residing in a terraced dwelling (OR = 0.48, p = 0.03), higher degrees of land-use mix (OR = 0.42, p = 0.03 for the high tertile) and having higher local-level street-network accessibility (‘movement potential’) (OR = 0.54, p = 0.03). Hillier topography with higher slope variability was associated with increased risks of psychological distress (OR = 1.38, p = 0.05).ConclusionsThe findings support our hypothesis that built environment configuration is independently associated with psychological distress. The study underscores the need for effective intervention in the planning and design of residential built environment to achieve the goal of health-sustaining communities.

Spatial accessibility and the spread of HIV-1 subtypes and recombinants

The global spread of HIV-1 main group (group M) has resulted in differential distributions of subtypes and recombinants, with the greatest diversity being found in sub-Saharan Africa. The explanations for the current subtype distribution patterns are likely multifactorial, but the promotion of human migrations and movements through transportation link availability and quality, summarized through 'accessibility', have been consistently cited as strong drivers. We sought to address the question of whether accessibility has been a significant factor in HIV-1 spread across mainland Africa through spatial analyses of molecular epidemiology, transport network and land cover data. The distribution of HIV-1 subtypes and recombinants in sub-Saharan Africa for the period 1998-2008 was mapped using molecular epidemiology data at a finer level of detail than ever before. Moreover, hypotheses on the role of distance, road network structure and accessibility in explaining the patterns seen were tested using spatial datasets representing African transport infrastructure, land cover and an accessibility model of landscape travel speed. Coherent spatial patterns in HIV-1 subtype distributions across the continent exist, and a substantial proportion of the variance in the distribution and diversity pattern seen can be explained by variations in regional spatial accessibility. The study confirms quantitatively the influence of transport infrastructure on HIV-1 spread within Africa, presents an approach for examining potential future impacts of road development projects and, more generally, highlights the importance of accessibility in the spread of communicable diseases.

Effect of Environmental and Lifestyle Factors on Hypertension: Shimane COHRE Study

BackgroundIn recent years there has been increasing evidence of an association between residential remoteness and hypertension (HTN); however, no study has examined the effects of residential remoteness-lifestyle associations on HTN. The objective of this study was to evaluate the effects of residential remoteness, as measured by road network distance and elevation, and lifestyle associations, including access to daily products as a measure of car use, on HTN in a rural region in Japan.MethodThis is a cross-sectional population based study. We analyzed data from the Shimane COHRE study conducted from 2006 to 2009 in the rural mountainous regions of Japan. After excluding missing data, we conducted a logistic regression analysis of the data for 1,348 individuals and examined the effects of residential remoteness and lifestyle associations, including road network distance, elevation and access to daily products as a measure of car use, on the prevalence of HTN.Principal FindingsIn participants without access to car use, the odds ratios for self-reported HTN (i.e. taking antihypertensive medication) were significantly increased in those living in moderate (odds ratio (OR): 2.21, 95% confidence interval (CI): 1.19–4.08) and far (OR: 2.55, 95% CI: 1.00–6.51) road distances, whereas there were no significant associations in participants with access to car use. There were no significant associations between elevation and HTN for participants either with or without access to car transportation.ConclusionsOur findings show that specific residential remoteness-hypertension associations vary according to access to daily products as a measure of car use in a rural mountainous area of Japan. These results advance the understanding and importance of considering residential environment, “where people live,” in establishing health policy.

Built environment configuration and change in body mass index: The Caerphilly Prospective Study (CaPS)

There exist no long term longitudinal studies assessing BMI trends of older adults in relation to the built environment. We employed cohort data from the Caerphilly Prospective Study (CaPS) to analyze the long term independent associations between a broad set of built environmental factors and change in BMI measured at three time points over a 12-year period. Built environment morphological metrics (morphometrics) used include measures of land use accessibility and space syntax modelled street network accessibility. A multilevel modelling framework was adopted wherein measurement occasions were nested within individuals and individuals were nested within LSOA census areas. BMI was observed to be significantly (p<0.05) associated with a number of built environment factors including mix; density of retail, churches, recreational and leisure services; street network accessibility as well as slope variability. Controlling for socio-demographic and lifestyle factors and for vascular diseases had negligible impact upon the influence of built environmental factors highlighting the importance of urban design and planning in community public health interventions.

Measuring national accessibility to cardiac services using geographic information systems

The Cardiac Access-Remoteness Index of Australia (Cardiac ARIA) used geographic information systems (GIS) to model population level, road network accessibility to cardiac services before and after a cardiac event for all (20,387) population localities in Australia., The index ranged from 1A (access to all cardiac services within 1 h driving time) to 8E (limited or no access). The methodology derived an objective geographic measure of accessibility to required cardiac services across Australia. Approximately 71% of the 2006 Australian population had very good access to acute hospital services and services after hospital discharge. This GIS model could be applied to other regions or health conditions where spatially enabled data were available.