Measuring compactness of the urban landscape within a city territory for environmental capabilities: the case of 50 cities in eastern China

[EN] When a compact city is pursued as the strategy for urban sustainability the understanding of compactness is varied from the developed countries to the developing countries. In China the historical cities are characterized with high density and mixed land use. After a short time of motorization they still show compact forms in the central city. A large amount of newly developed areas are distributed in clusters near or far from the center. The crop land and natural habitat are encroached to different degrees. This paper developed an approach to measure the structural compactness of urban landscape patches within a city territory. It included six spatial metrics to measure the shape and density of the central agglomeration, the area configuration and distant relationship between the central agglomeration and the other clusters, and the distribution of all urban patches. By this approach the 50 cities in eastern China were categorized into five classes of forms: one center, multi-centers, centralized groups, cluster groups and scatter. Then the vegetation biomass loss with urban expansion was calculated based on remote sensing data, and used to assess the environmental capability of the five types of urban form. The suggestions of urban form optimization could be put forward for the five categories of cities.Shuang, CS.; Tong, Z.; Guangyu, L.; Yue, Y. (2018). Measuring compactness of the urban landscape within a city territory for environmental capabilities: the case of 50 cities in eastern China. En 24th ISUF International Conference. Book of Papers. Editorial Universitat Politècnica de València. 13-20. https://doi.org/10.4995/ISUF2017.2017.5094OCS132

Measuring heterogeneity in urban expansion via spatial entropy

The lack of efficiency in urban diffusion is a debated issue, important for biologists, urban specialists, planners and statisticians, both in developed and new developing countries. Many approaches have been considered to measure urban sprawl, i.e. chaotic urban expansion; such idea of chaos is here linked to the concept of entropy. Entropy, firstly introduced in information theory, rapidly became a standard tool in ecology, biology and geography to measure the degree of heterogeneity among observations; in these contexts, entropy measures should include spatial information. The aim of this paper is to employ a rigorous spatial entropy based approach to measure urban sprawl associated to the diffusion of metropolitan cities. In order to assess the performance of the considered measures, a comparative study is run over alternative urban scenarios; afterwards, measures are used to quantify the degree of disorder in the urban expansion of three cities in Europe. Results are easily interpretable and can be used both as an absolute measure of urban sprawl and for comparison over space and time.Comment: 23 pages, 7 figure

Urban form indicators as proxy on the noise exposure of buildings

Available online 27 September 2013The present paper aims to address the problems of the urban environment as an area of interaction between urban forms and urban noise. This interaction is intended to be monitored using urban indica-tors, by comparing the effects of noise propagation using models of urban forms. The model of noise pre-diction allowed developing noise studies in facades, resulting in noise levels in a calculation grid located in the building facades. The study will allow the creation of different scenarios and anticipate as early as in the preliminary building design phase, which facades would be exposed to higher noise levels. The effects of noise in facades can then be minimized in advance, by adjusting the layout of the urban typology

Low-income housing layouts under socio-architectural complexities: A parametric study for sustainable slum rehabilitation

Lack of sustainable slum redevelopment guidelines in India is a policy gap that needs immediate attention. A rational design and planning route is necessary to ensure sustainability of the upcoming low-income (LIG) housing stocks. In this study, we performed a cross-sectional evaluation of LIG housing layouts through a socio-architectural and site-based wind-flow analysis route. We hypothesise that a better indoor environment in the LIG housing can be achieved through a better wind driven natural-ventilation in the living spaces, which is a function of the housing layout. Specific objectives of this study were: i) to investigate the influence of socio-architectural and geometric parameters on the LIG housing layouts; ii) to examine the effect of site-wind flow on LIG housing layouts using CFD simulations. BDD chawls of Mumbai were adopted as the case study. Results show that the current form of the LIG houses had a poor indoor environment and social interaction spaces, while the hypothesised iterated layout ‘Form A’ performed better in all the socio-architectural and wind-flow metrics that can promote relatively better quality of life. This study is a first-step approach for the development of regulatory guidelines in LIG housing design that is coherent to the context of the space.Ministry of Human Resource Development, Government of India Commonwealth Scholarship Commission Cambridge Trus

The impact of urban form on commuting in large Chinese cities

Studies on cities in Europe and the United States have demonstrated that travel behaviour is influenced by urban form. Based on these findings policies steering the shape of cities have been proposed to reduce urban transport emissions and limit congestion. Such policies can also be relevant for the rapidly growing and motorising Chinese cities. Yet, empirical evidence on the relationships between urban form and car usage is scarce for the specific Chinese context that is characterised by high densities, fast development and strong government steering. Using novel crowd-sourced datasets we study the impact of several urban form variables (city size, urban density, land-use mix, polycentricity and spatial clustering) on the cost of commuting expressed in time and distance. The results show that city size and spatial clustering are important determinants of commuting: large cities without clear clusters of businesses and other facilities have longer average commuting times and distances. Increased prosperity also adds to longer and lengthier commutes. Spatial planning measures that maintain or reinforce high-density clusters can help limiting commuting distance and time. Current sprawled urban development may have long-term, negative consequences for the accessibility and liveability of Chinese cities and could hamper their economic potential

The compact city in empirical research: A quantitative literature review

The ‘compact city’ is one of the most prominent concepts to have emerged in the global urban policy debate, though it is difficult to ascertain to what extent its theorised positive outcomes can be substantiated by evidence. Our review of the theoretical literature identifies three main compact city characteristics that have effects on 15 categories of outcomes: economic density, morphological density and mixed land use. The scope of our quantitative evidence-review comprises all theoretically relevant combinations of characteristics and outcomes. We review 321 empirical analyses in 189 studies for which we encode the qualitative result along with a range of study characteristics. In line with theoretical expectations, 69% of the included analyses find normatively positive effects associated with compact urban form, although the mean finding is negative for almost half of the combinations of outcomes and characteristics