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"Urban structure"
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Assessing the role of urban green spaces for human well-being: a systematic review
Human has been evolving in a natural environment over a long time; thus, he is habitual to adapt it. Green spaces are obligatory landscapes in an urban structure that provide a natural environment and accelerate other life events. In contrast, unplanned urbanization, and conversion from green to grey structures have damaged natural environmental resources. Studies through different angles have highlighted the importance of urban green spaces for human well-being but now need to identify their role according to the potential. The demands of urban green spaces may differ with the change of population size, types of grey structure, urban expansion, the altitude of the place, and geographical location. Therefore, this systematic review aims to analyse the significance of urban green spaces for human well-being. The study opted for a systematic process during the selection and organization of studies for this review. After analysing, 46 studies were finalized with the consensus of three review authors. Accordingly, literature was analysed under the central theme of “Urban Green Spaces for Human Well-being.” Human Well-being was assessed under six sub-themes; physical, psychological, mental, social, subjective, and environmental well-being. The review concluded that urban green spaces are the primary pillar for a sustainable urban place and human well-being due to highly positive and positive correlations. Moreover, the study did not find any demarcation line between green spaces and grey structures according to any specific need. Therefore, the study suggested that the role of urban green spaces for human well-being should be analysed according to their potential and required optimal ratio under different communities’ urban specific environments and social behaviour.
Journal Article
Does the monocentric model work in a polycentric urban system? An examination of German metropolitan regions
In explaining the determinants of urban spatial structure, researchers have relied on the traditional monocentric ‘Alonso-Mills-Muth’ model. This article contributes to this discussion by testing the viability of the monocentric model when applied to metropolitan areas in Germany, a country traditionally associated with a polycentric urban structure, regional differences and urban shrinkage. We estimate the model with a unique dataset covering 92 metropolitan areas over two time periods (2000 and 2014), which allows estimation in both a cross-sectional and a panel framework. Using spatial and panel regression techniques, we test whether the underlying determinants of urbanisation vary according to factors unique to the German context, including the roles of historical geography, regional polycentricism and urban shrinkage. We found that, similar to the US studies, the model performed reasonably well, particularly with the overall fit and the performance of the population variable, which was significant and positively related to urbanised area. Personal income and land prices showed mixed results, and the coefficients for transportation costs proved to be challenging. We also found that regional geography matters: a region in eastern Germany is smaller than one in the west. A proxy variable for regional polycentricity was not significant. Finally, we found that the model’s behaviour differs between growing and shrinking regions, most notably in the differing impacts that population change has on the change in urbanised area.
在解释城市空间结构的决定因素时，研究者们一直依赖传统的单中心“阿隆索-米尔斯-穆特 (Alonso-Mills-Muth)”模型。本文通过测试单中心模型在德国大都市地区的有效性来促进这一讨论。德国传统上是一个多中心城市结构、地区差异和城市萎缩的国家。我们使用涵盖两个时间段（2000年和2014年）的92个大都市地区的独特数据集来估计模型，这允许在横截面和面板框架中进行估计。利用空间和面板回归技术，我们测试了城市化的潜在决定因素是否因德国独特的因素而有所不同，包括历史地理、区域多中心主义和城市收缩的影响。类似于针对美国的研究结果，我们发现该模型的表现相当好，特别是总体拟合和人口变量的表现，其与城市化地区显著正相关。个人收入和土地价格显示出混合的结果，运输成本的系数显示出对模型的挑战。我们还发现区域地理很重要：德国东部的一个区域比西部的一个区域显示的相关性要小一些。区域多中心性的一个代理变量未显示出显著的相关性。最后，我们发现增长和萎缩地区的模型表现不同，最显著的是人口变化对城市化地区变化的不同影响。
Journal Article
New spatialities of work in the city
This introduction discusses the objectives and concepts underlying the Special Issue on the new spatialities of work in the city. It highlights the urban impact of both the changing spatiotemporal working patterns and the increased diversity of workspaces that have resulted from post-industrial restructuring, globalisation, labour market flexibilisation and digitisation. Even pre-COVID-19, when the research in this Special Issue was undertaken, this impact on the urban structure and the social fabric of cities was significant, but it had remained underexplored. Here, therefore, we question models of work and commuting that continue to assume the spatially ‘fixed’ workplace, and explore how new understandings of workspace and multi-locality, developed in this Special Issue, can inform future research. This, we argue, is more important than ever as we come to understand the medium- and long-term impacts of pandemic-altered work practices in cities. We further argue that the spatialities of work need to be connected with research on health, job quality and wellbeing in cities – such as, for example, on the risks that COVID-19 has exposed for driving and mobile work.
这篇介绍探讨本期关于城市工作的新空间性的特刊的基本目标和概念。我们凸显了不断变化的时空工作模式和工作空间日益多样化对城市的影响，这些都是由后工业重组、全球化、劳动力市场弹性化和数字化带来的结果。甚至在新冠疫情爆发之前，当本期特刊的研究工作正在进行时，这种对城市结构和城市社会组织的影响就已经非常明显了，但却未得到充分研究。因此，在本文中，我们质疑继续以空间“固定”工作场所为假设的工作和通勤模型，并探讨本期特刊中所发展的对工作空间和多地点的新理解对未来研究的参考价值。我们认为，随着我们越来越了解疫情造成的城市工作实践的改变的中长期影响，这比以往任何时候都更加重要。我们进一步认为，工作的空间性需要与城市健康、工作质量和幸福感的研究联系起来，例如，新冠肺炎所暴露的驾驶和流动工作的风险。
Journal Article
A longitudinal study of changes in intra-metropolitan employment concentration in Beijing
This article explores the spatial trend of intra-metropolitan employment concentration in the Beijing metropolitan area from 2004 to 2013. We use multiple-year economic census data and construct a unique longitudinal dataset of employment at the subdistrict level, applying the locally weighted regression method to identify employment centres in Beijing. The results show that jobs continued to decentralise from the urban core to the suburbs in Beijing over the studied period; however, different from the common trajectory of Western metropolitan spatial evolution, decentralised jobs tended to be more concentrated in subcentres and the polycentric urban structure prevailed in Beijing. Polycentricity strengthened in Beijing from 2004 to 2008, but job dispersion increased at the expense of polycentricity during 2008–2013. However, job dispersion did not follow an unstructured model; instead, subcentres played an increasingly important role in structuring the dispersed jobs. Job dispersion in Beijing has been more associated with the scatteration of service jobs, while manufacturing jobs tended to be more concentrated in subcentres, which contributed to the polycentric development of the capital. We also observe the persistence in the location of employment centres in Beijing over the studied period, as well as substantial spatial changes in the boundaries of employment centres, which suggests that the employment concentrations within the metropolitan area are persistent but not static.
本文探讨了2004-2013年期间北京大都市区内就业集中度的空间趋势。我们使用多年经济普查数据，构建了一个独特的街道一级就业纵向数据集，应用局部加权回归方法确定北京的就业中心。结果表明，在作为研究对象的期间，北京的就业持续从城市核心向郊区分散；然而，与西方大都市空间演变的通常轨迹不同，分散的工作往往更集中在次中心，而北京的多中心城市结构非常明显。从2004年到2008年，北京的多中心性得到了加强，但在2008年到2013年期间，工作分散的增加是以多中心性为代价的。然而，工作分散并不遵循非结构化模型；相反，次中心在构建分散的工作岗位方面发挥着越来越重要的作用。北京的就业分散更多地与服务业就业分散联系在一起，而制造业就业往往更集中在次中心，这有助于首都的多中心发展。我们还观察到，在作为研究对象的期间，北京就业中心位置的持续性，以及就业中心边界的显著空间变化，这表明大都市地区的就业集中是持续的，但不是静态的。
Journal Article
Spatial gradients of urban land density and nighttime light intensity in 30 global megacities
The spatial agglomeration of urban elements results in the center-periphery urban structure, but the difference in spatial gradients of socioeconomic and physical elements is unclear. This study investigates how urban land density (ULD) and nighttime light intensity (NLI) decline with the distance to center(s) using the inverse-S function. Taking 30 global megacities as examples, we acquired their urban land and nighttime light in 2020 to represent urban physical and socioeconomic elements, respectively. ULD and NLI in concentric rings have been calculated to compare their spatial gradients from the city center(s). Results show that both ULD and NLI decrease slowly around city centers, followed by a relatively quick decline to suburban areas, and then decrease slowly again to a background level, showing an inverse-S shape. This spatial gradient can be well-fitted by the inverse-S function, whose parameters reflect disparities in urban extents and urban forms. NLI decreases faster than ULD, resulting in smaller radii (extents) of NLI, which shows the spatial agglomeration of socioeconomic elements is more obvious than that of physical space. This gap requires balanced development of socioeconomic and physical elements in megacities to avoid low-density urban sprawl and promote sustainable urban development.
Journal Article
The impact of urban spatial structure on air pollution: empirical evidence from China
For a long time, air pollution caused by unreasonable urban spatial structure and excessive urban sprawl has been a prominent environmental problem in China. From the level of all cities, three economic zones and different city scales, panel data of 194 prefecture-level cities in China from 2006 to 2017 were used to construct a dynamic panel model and to analyze the impact of urban spatial structure on SO
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, industrial smoke and dust emissions. The results showed that: (1) air pollution had a time cumulative effect year by year, the air pollution of the last year could add air pollution in the script year; (2) urban space expansion could effectively curb air pollution; (3) the urban spatial structure with high population compactness made the air pollution change in an inverted \"U\" shape; (4) in different economic zone levels and different urban scale levels, the direction of influence and intensity of urban spatial structure on air pollution was different. In the eastern region of China, the residential land, public facilities land and traffic land in the urban structure mainly affected the air pollution. In the central region, the residential land, industrial land, traffic land and municipal land in the urban structure had a significant impact on the air pollution, while the urban scale was the main cause of the air pollution in the western region. Based on this, we recommended the reasonable planning of land use structure, establishment of a population density regulation mechanism, and paying attention to regional differences and urban size differences. This study can help managers of different economic zones and cities of different sizes to improve urban spatial structure and control air pollution in the process of urban development.
Journal Article
Measuring polycentricity via network flows, spatial interaction and percolation
Polycentricity, or the number of central urban places, is commonly measured by location-based metrics (e.g. employment density/total number of workers, above a threshold). While these metrics are good indicators of location ‘centricity’, results are sensitive to threshold choice. We consider the alternative idea that a centre’s status depends on its connectivity to other locations through trip inflows/outflows: this is inherently a network rather than place idea. Three flow and network-based centricity metrics for measuring metropolitan area polycentricity using journey-to-work data are presented: (a) trip-based; (b) density-based; and (c) accessibility-based. Using these measures, polycentricity is computed and rank-centricity distributions are plotted to test Zipf-like or Christaller-like behaviours. Further, a percolation theory framework is proposed for the full origin–destination matrix, where trip flows are used as a thresholding parameter to count the number of sub-centres. Trip flows prove to be an effective measure to count and hierarchically organise metropolitan areas and sub-centres, tackling the arbitrariness of defining any threshold on employment statistics to count sub-centres. Applications on data from the Greater Sydney region show that the proposed framework helps to characterise polycentricity and sub-regional organisation more robustly, and provide unexpected insights into the connections between land use, labour market organisation, transport and urban structure.
多中心性、或中心城市地点的数量通常通过基于位置的度量指标（例如，高于阈值的就业密度/工人总数）来衡量。虽然这些指标是位置“中心性”的良好指标，但结果对阈值选择很敏感。我们考虑另一种概念，即中心地位取决于其通过出行流入/流出与其他位置的连接性：这本质上是一个基于网络而非基于位置的概念。我们采用通勤数据，提出了用于测量都市区多中心性的三种基于流量和网络的中心性度量指标：（a）基于出行的；（b）基于密度的；（c）基于可访问性的。使用这些度量指标，我们计算多中心性并绘制中心性分布，以测试齐夫（Zipf）定律行为或克里斯泰勒（Christaller）定律行为。此外，我们针对完整的始发地—目的地矩阵提出了渗流理论框架，其中出行流量被用作计算次中心数量的阈值参数。出行流量被证明是计算大都市区和次中心数量并确定其结构的有效度量指标，解决了定义就业统计数据的任意阈值以计算次中心数量的任意性。对大悉尼地区数据的应用表明，提议的框架有助于更好地描述多中心和次区域结构，并对土地利用、劳动力市场组织、运输和城市结构之间的联系提供意想不到的见解。
Journal Article
15-min Cities: the Potential of a Medium-Sized Polycentric Latin American City
Urban sustainability and sustainable mobility have become the central focus of sustainable development initiatives. The city of 15 models seeks to ensure that urban development is sustainable. This paper evaluates the current state of mobility and the use of sustainable transport in the specific context of the city of Antofagasta, which, due to its characteristics of urban expansion and its mining activity, has been considered an international reference case. In particular, we study how the current urban structure shapes the city’s travel patterns and identify opportunities for public policy actions to focus their investment and urban intervention efforts on the essential aspects that make it possible to achieve 15- or 20-min territories. The results reveal the need for urban development initiatives to focus on improving the supply of goods and services in areas with low installed capacity, promoting the culture of micro-neighbourhoods, and encouraging cycling. In particular, only 10% of trips, for all purposes and all modes of transport, are completed in less than 15 min. And about 58% of trips, for all purposes and all modes, are completed in less than 30 min. In the marginal effects of the multinomial logit model, a one-unit increase in travel time increases the probability of choosing to travel by public transport by 63% and decreases the probability of walking by 41%.
Journal Article
A complex network perspective for characterizing urban travel demand patterns: graph theoretical analysis of large-scale origin–destination demand networks
Urban travel demand, consisting of thousands or millions of origin–destination trips, can be viewed as a large-scale weighted directed graph. The paper applies a complex network-motivated approach to understand and characterize urban travel demand patterns through analysis of statistical properties of origin–destination demand networks. We compare selected network characteristics of travel demand patterns in two cities, presenting a comparative network-theoretic analysis of Chicago and Melbourne. The proposed approach develops an interdisciplinary and quantitative framework to understand mobility characteristics in urban areas. The paper explores statistical properties of the complex weighted network of urban trips of the selected cities. We show that travel demand networks exhibit similar properties despite their differences in topography and urban structure. Results provide a quantitative characterization of the network structure of origin–destination demand in cities, suggesting that the underlying dynamical processes in travel demand networks are similar and evolved by the distribution of activities and interaction between places in cities.
Journal Article