Estimating road network accessibility during a hurricane evacuation: A case study of hurricane Irma in Florida

Understanding the spatio-temporal road network accessibility during a hurricane evacuation—the level of ease of residents in an area in reaching evacuation destination sites through the road network—is a critical component of emergency management. While many studies have attempted to measure road accessibility (either in the scope of evacuation or beyond), few have considered both dynamic evacuation demand and characteristics of a hurricane. This study proposes a methodological framework to achieve this goal. In an interval of every six hours, the method first estimates the evacuation demand in terms of number of vehicles per household in each county subdivision (sub-county) by considering the hurricane’s wind radius and track. The closest facility analysis is then employed to model evacuees’ route choices towards the predefined evacuation destinations. The potential crowdedness index (PCI), a metric capturing the level of crowdedness of each road segment, is then computed by coupling the estimated evacuation demand and route choices. Finally, the road accessibility of each sub-county is measured by calculating the reciprocal of the sum of PCI values of corresponding roads connecting evacuees from the sub-county to the designated destinations. The method is applied to the entire state of Florida during Hurricane Irma in September 2017. Results show that I-75 and I-95 northbound have a high level of congestion, and sub-counties along the northbound I-95 suffer from the worst road accessibility. In addition, this research performs a sensitivity analysis for examining the impacts of different choices of behavioral response curves on accessibility results.     

A comparative analysis of transportation-based accessibility to mental health services

The demand for mental health services has been growing stronger over the last couple of decades. This indicates the need to study and assess the access to these mental health services especially with a focus on the vulnerable populations having the greatest need. As such, this paper presents a Geographical Information Systems (GIS)-based analysis in order to study and evaluate the accessibility of mental health facilities using the information on the spatial distributions of population and facilities, and regional traffic characteristics. For this purpose, different age group segments are utilized including the total population as well as those aged between 18 and 21, 22 and 49, 50 and 64, and those aged over 65 and 85. Focusing on the State of Florida, spatially detailed accessibility metrics are calculated with regard to healthcare facilities using travel times between population block groups and these critical mental health facilities. These estimates are used to calculate the weighted county accessibility scores for each county. Findings clearly delineate those counties that lack access to mental facilities, especially those in Northwest Florida, a demographically diverse and substantially rural region. This type of analysis can help planners and policy makers develop better strategies in order to provide adequate mental health care options needed in targeted locations.     

Logistics connectivity considering import and export for Chinese inland regions in the 21st-Century Maritime Silk Road by dry ports

This investigation studies the logistics connectivity of inland Chinese provinces along the 21st-Century Maritime Silk Road (MSR) from the perspective of the oriented cooperation relationship between seaports and dry ports in inland regions. The logistics connectivity is measured based on the import and export data. First, complex network theory is used to develop a system for evaluating logistics connectivity of inland regions, involving metrics of susceptible-infected-recovered, and improved closeness centrality proposed to drawing on the characteristics of the studied network based on closeness centrality. Second, based on collected data, 136 dry ports in China and 127 seaports along the MSR have been used to construct an empirical network that covers 15 inland provinces of China. Then, the accessibility and importance of inland provinces are analyzed, and key points that serve the improvement of the logistics connectivity of inland provinces are mined and summarized. An example of an improved scheme for the connectivity of inland provinces is presented to demonstrate the application of these key points. The conclusions drawn support decision-making for local governments to improve the logistics connectivity of inland regions in the international logistics network, and then strengthen the participation of inland provinces in the MSR.     

基于可达性指标的轨道交通外部性价值分析

城市轨道交通具有显著正外部效益,研究由此带来的价值,将有利于制定合理的城市轨道交通发展规划与融资模式。以大连市为例,基于可达性指标,建立特征价格模型,计算轨道交通外部性价值。模型结果得出城市轨道交通可达性指标提高,将使其正外部性效益增强,且合理的城市规划将极大提高城市轨道交通的外部性价值。     

就业可达性量化方法及分布特征研究——以南京市为例

基于国外传统可达性测算方法,建立适用于中国城市交通特征的就业可达性量化方法。在对比分析常用的四种可达性测算模型的基础上,以南京市为实例,针对老城区分别构建了小汽车和公共汽车出行就业可达性模型,同时建立新城区就业可达性模型,以此分析南京市就业可达性空间分布特征。研究表明：南京市主城区就业可达性随着出行距离增加而提高,且提高程度逐步降低;公共汽车出行就业可达性低于小汽车,在城市外围地区尤为明显;新城区就业可达性远低于老城区,职住失衡以及交通通道欠缺是主要原因。最后,通过借鉴国际城市发展经验,提出南京市不同片区就业可达性改善措施。     

轨道交通站点开发利益影响范围研究

利用零售力法则计算轨道站点被城市各中心吸引的概率,并利用可达性指标计算各站点在单中心影响情况下的轨道站点影响范围,结合以上两模型确定轨道站点开发利益影响范围计算模型。该模型能够用于城市多中心情况下轨道站点开发利益影响范围及相邻站点间影响范围分界线的计算,并能为轨道沿线土地利用开发、交通接驳设施设计以及轨道交通开发利益还原提供技术支持。     

Rural mobility and mode choice: Evidence from the 2001 National Household Travel Survey

This article uses data from the 2001 National Household Travel Survey (NHTS) to compare travel behavior in rural and urban areas of the U.S. As expected, the car is the overwhelmingly dominant mode of travel. Over 97% of rural households own at least one car vs. 92% of urban households; 91% of trips are made by car in rural areas vs. 86% in urban areas. Regardless of age, income, and race, almost everyone in rural areas relies on the private car for most travel needs. Mobility levels in rural areas are generally higher than in urban areas. That results from the more dispersed residences and activity sites in rural areas, which increase trip distances and force reliance on the car. Somewhat surprisingly, the rural elderly and poor are considerably more mobile than their urban counterparts, and their mobility deficit compared to the rural population average is strikingly less than for the urban elderly and poor compared to the urban average. Data limitations prevented a measurement of accessibility, however, and it seems likely that rural areas, by their very nature, are less accessible than urban areas, especially for the small percentage of car-less poor and elderly households.     

基于多路径的城市轨道交通网络末班车动态可达性研究

城市轨道交通网络末班车动态可达性基于空间可达性的时间可达性。空间可达性为路网的有效路径集,取决于路网物理结构、有效路径K值、换乘走行时间和区间运行时间等。时间可达性是在空间可达性有效路径集的基础上,匹配列车时刻表和换乘走行时间,从而确定各路径的末班车时间以及OD(起讫)对的末班车时间。分别从空间可达性和时间可达性两个方面着手,研究网络末班车动态可达性推算方法,并以广州轨道交通路网为例,验证了该方法的有效性和可行性。城市轨道交通网络末班车动态可达性计算可为乘客提供末班车时刻查询以及相应的可达路径信息。     

高铁时代甘肃省中心城市可达性演变特征分析

高铁时代,铁路网的完善与高速铁路建设对沿线中心城市可达性变化产生重要影响。选取2008年、2015年及2025年作为时间断面,以甘肃省14个地级市及全国交通数据为基础,应用可达性技术分析方法对高铁通车前后沿线中心城市的交通可达性演变进行研究。研究结果表明:2025年高铁时代,中心城市之间的交通可达性水平显著提高;沿线中心城市对周围地区辐射影响增强;宝兰客运专线建成使得天水至西安段交通可达性增幅超两倍;兰渝高铁的建成缩短甘肃省至中部及南方大部分省份时间,实现地理时空有效收敛。"一带一路"背景下,研究可达性演变有利于廓清各地市空间发展导向,明晰省内各地区和省际地区间的联系,为区域空间发展战略的制定提供参考。     

高速铁路建设对沿线城市经济发展的促进作用

国内外诸多经典理论研究表明,城市的发展与地理环境、资源、人口、交通网络等诸多因素有关,其中城市交通和城市间的铁路交通网对城市的形成与经济发展影响最大。此文在阐述国内外高速铁路发展概况的基础上,依据城市经济学相关理论,建立城市通达性与城市经济总量的关系模型,通过选取样本空间,进行相关数据归纳和分析,论述高速铁路建设缩短了城市间的时空距离,提高了城市间的通达性,加快了区域间资源、技术及信息的交流,增加了城市的GDP总量,促进了城市经济的发展,对中部城市经济发展的促进作用更加明显。