Street Morphology Research Articles

Urban Form and Urban Materials as Controller of Urban Climate in Valparaiso, Chile

The urban heat island (UHI) effect on the city and urban climate are related whit urban form and urban materials: it’s an evidence of human influence in climate change. Into the cities, the air temperature increases in downtown and go to outskirts decreases. Valparaíso, Chile, is located in a Mediterranean climate in the southern hemisphere (-33°03’). The urban area of the city is 400 km2 and its population reaches 300,000 inhabitants. The behaviour of air temperature in the city in winter and summer and on sunny days and cloudy days has been recorded. In all days heat island phenomenon is registered. A greater increase of UHI in summer and in sunny day has been recorded. The variation of the temperatures of the materials that make up the urban canyons has also been recorded, presenting different dispersions and variation according to whether it is a sunny day or a cloudy day. In sunny day all day a large dispersion is registered, at afternoon spatially. An important factor in the behaviour of the street climate is its morphology. This condition has been recorded with the visible sky factor (SVF) and with the geographic orientation of the studied canyons. Both the global urban form, the visibility of the sky, the street morphology and the materials of the city affect the urban air temperature variations. City normative planning and designers should consider these variables and its influences.

Accessibility and Street Network Characteristics of Urban Public Facility Spaces: Equity Research on Parks in Fuzhou City Based on GIS and Space Syntax Model

Urban green spaces are conducive to people’s physical, mental, and social health; however, in many cases, these benefits are unevenly distributed in cities. This study explored the equity of urban green spaces in terms of accessibility and spatial morphology, specifically, (1) applied the geographic information system (GIS) accessibility index to the equity of parks in Fuzhou City; (2) discussed the accessibility of parks and the spatial morphological characteristics of streets from a space syntax analysis; (3) examined the correlation between the accessibility of parks in Fuzhou City and the spatial morphology of streets. The results provide a valuable reference for sustainable urban design and planning.

Analysis of the Geographical-Information Impact on the Performance of ABS-CRE HetNets

In this paper, we analyze the performance of Heterogeneous Networks (HetNets) that are operating under Almost Blank Subframes (ABS) and Cell Range Expansion (CRE) by taking into consideration the effect of geographical information. In order to achieve such analyses, we develope a simulator that incorporates data from a Geographic Information System (GIS); specifically, a set of parameters that define the morphology of buildings and streets in urban areas. We describe the implemented methods to estimate the received power, as well as the average throughput, over an area of interest. Our numerical results clearly demonstrate that the overall network performance significantly depends on geographical information; hence our main contribution consists in developing a simulator that incorporates such information in the analysis and evaluation of ABS-CRE HetNets, which allows proposing design guidelines to improve the performance of these networks in realistic scenarios. To the best of our knowledge, this kind of proposal has not been reported in previous works.

Spatial morphology of an Australian high street: a century of retail change in Subiaco town centre

ABSTRACTThis paper describes an empirical case study of the Subiaco town centre in Western Australia. The research method employs geospatial mapping of archival and contemporary data sources to explore the town centre's changing spatial structure and high street morphology at the micro-scale over the past century. Once a thriving retail and business centre, Subiaco's (and possibly the state's), premier retail high street destination is now being compromised as the disruptive influence of online retailing gains further traction in the marketplace. Retail disruption provides the paper's conceptual foundation. Agents of disruption include the processes of creative destruction and innovation diffusion, which together with macro-economic factors help to explain the centre's evolution over time and space. The paper examines changes in the town centre's morphological character including residential gentrification, a growing dominance of fast food outlets, an overabundance of comparison stores and a more gendered offering in retail and personal services establishments. The paper also refers to the potential of the town centre to regain its past residential status as a means of fostering economic growth and renewal and suggests that this will only be achieved with radical intervention at the policy and planning level.

Effect of Street Morphology on Buildings’ Thermal Storage in a Hot and Arid Climate: Case Study of Biskra (Algeria)

This work is an experimental study focusing on the relationship between street morphology and thermal storage in buildings. The first aim of this study is to reduce air conditioning usage in hot and arid areas, taking as example Biskra city (Algeria), during the long summer period (5 months), by reducing thermal storage. This leads to the reduction of carbon emissions to a level higher than the individual construction level in order to design a sustainable city, using measuring instruments (kimo HD 100 and Cason CA 380), we measured outdoor air temperature, wall temperature, relative humidity and wind speed on three street morphologies ; the (canyon, dihedral and open streets). These streets are different in terms of morphological indicators such as Sky View Factor (SVF) and albedo materials (a). We also applied mathematical equations across the thermal balance to calculate thermal storage. Our second goal was to identify the morphological indicators of the streets affecting the thermal storage of buildings. In this context, the obtained results showed that SVF was the most influential parameter on the heat storage.

Characterizing the morphology of real street models and modeling its effect on thermal environment

This paper investigates the correlation between street morphology and thermal environment of six street models representing the central morphology of Barcelona (Spain), Berlin (Germany), London (UK), New York (US), Nanjing (China) and Paris (France). The morphology is first characterized through morphological indices (i.e. opening and closing ratios, smoothness ratio, symmetry ratio) obtained from a novel “street morphology extraction” method, which allows to depict a certain feature of the geometry (the presence of openings, the shape of building envelopes and the symmetry of the street, respectively). It is found that the average Sky View Factor (SVF) is negatively correlated with the building density, the closing ratio and the symmetry ratio, and positively correlated with the opening ratio. Then, air temperature (AT), Mean Radiant Temperature (MRT) and Predicted Mean Vote (PMV) are obtained from ENVI-met simulations to assess how the thermal environment is affected by the street morphology. In particular, the average AT, MRT and PMV are positively correlated with average SVF at 12:00 and with the building density at 21:00. The presence of openings, the shape of building envelopes and the symmetry of the street differently affect the local thermal environment and comfort during the day, leading to different MRT and PMV distribution. For example, the Barcelona model, due to high building density, smoothness and symmetry, which prevent ventilation, experiences slightly warm conditions also in the night. The novel morphometric method proposed allows studying which feature mostly affects the thermal environment and can thus be employed in the early planning stage.

The Influence of Urban Green Systems on the Urban Heat Island Effect in London

Urban areas are typically warmer than rural ones. This is mainly due to denser configuration dominated by impermeable surfaces such as buildings and roads, compared to rural areas which are less densely built and mainly dominated by open spaces. Rapid urban expansion in dense cities bares direct impact on surface and air temperature patterns within street canyons; a phenomena which is known as the Urban Heat Island (UHI) effect. Thus, several UK city councils such as Birmingham, Manchester, and London have started to develop strategies aiming at enhancing urban green systems (UGS) through trees, green walls and green roofs. Some of those strategies include considering the green space factor, and increasing green areas within the cities to improve street canyon microclimate and reduce UHI. The Mayor of London has adopted a strategy for London 2050 aspiring to transform it to be the greenest city in the world by increasing the green areas up to 50%. This paper investigates the influence of increasing the UGS percentage which is considered as a key solution to mitigate UHI effect which will, in turn, provide thermally comfortable outdoor environments for pedestrians. The investigation is undertaken by comparing the morphology of precincts and streets in relation to air temperature, mean radiant temperature and surface temperature within Oxford Street canyons in London city centre; being one of the world’s busiest streets. The results from this research demonstrate that different UGS interventions with varying percentage are required depending on particular canyon orientations and geometries. The study found that, in general, more trees would have significant thermal comfort effect followed by living façade, while high albedo pavement (HAP) came last. However, HAP had high influence on improving thermal comfort in North-South orientated streets with minor variance to trees and living facades which, changing their percentage levels was insignificant.

Energy Planning and Urban Form: Solar Energy as a Design Parameter in Ouargla, a Southern City in Algeria

Energy planning plays a crucial role in the built environment, particularly when aiming at reaching sustainable cities. Today, most researchers are focusing on exploring the accurate potential of renewable energies. However, few studies have explored the correlation between urban forms and renewable energy inputs. The objective of this paper is to examine the relationship between the incident solar irradiation, urban form and the potential of photovoltaic energy at a local level. The study focuses on the case of the city of Ouargla, which is located in southern Algeria. In terms of methodology, it adopts three main steps. Firstly, three different types of urban form have been identified according to three main criteria (morphology of streets and lot, buildings use and environment). Secondly, numerical simulations were performed based on 3D models of these urban forms, with the purpose of evaluating the distributions of solar irradiations on the different building roofs, which helps to determine the most appropriate urban form for solar energy use. The study demonstrates that urban form has an impact on solar energy potential, which means that the latter provides a significant increase in the photovoltaic energy production.

Exploring the association between the built environment and remotely sensed PM2.5 concentrations in urban areas

Haze, especially PM2.5, poses a serious threat to public health in China. PM2.5 primarily originates from urban activities, and built environment may affect its formation and dispersion. Previous studies were based on limited data from ground-monitoring stations, and high resolution pollution maps are unavailable for statistical analyses. In this study, a 1 km*1 km wall-to-wall map of PM2.5 concentration is developed with remote sensing data in Wuhan, China, and spatial statistics are used to figure out the influence of the built environment on PM2.5 concentrations. In terms of land cover, high-rise high-density building areas have the largest impact on PM2.5 concentrations, and the effect of forestland on the concentrations is not obvious in winter. In terms of land use, industrial lands are unrelated to air pollution in the downtown, while transportation has become a main source of PM2.5 pollution. In terms of urban form, floor area ratio and building density are positively associated with PM2.5 concentrations, and different types of road densities have different effects on air pollution. Finally, the implications of the study for urban planning and development are given. It is necessary to develop a polycentric urban structure to balance high population density and reduce traffic emissions in downtown areas. Road and bus networks should be optimized simultaneously to reduce traffic emissions and “small blocks and narrow roads” may be considered as an alternative for urban development. The spatial morphology of streets and buildings should be considered during urban design and urban renewal. In general, the study contributes to the application of remote sensing in urban planning and development, and remotely sensed PM2.5 concentration data could provide further findings than the air pollution data obtained from ground monitoring and “bottom-up” models in past studies.

Public participatory historical GIS

Building historical geographic information system (HGIS) datasets is time consuming and very expensive, especially when built at the scales that permit analysis of the lived experiences of individuals or the morphology of buildings or streets. Further, these datasets are often built exclusively in the academy, with little input from the contemporary communities they represent. In this paper, we review the use of the public in crowdsourcing historical data creation, and using the Keweenaw Time Traveler set in Michigan’s Copper Country as a case study, we call for a new approach to HGIS scholarship that includes a robust public partnership to building HGIS datasets. The creation of a public participatory HGIS approach to HGIS scholarship can increase efficiencies of, public relevance in, and extend the reach of, HGIS projects beyond the academy. We have established a set of best practices that include, incorporating the public in the HGIS interface design, providing immediate public data access, contextualization of spatial data in space-time, comprehensive public history outreach in person and online, and creating affordances for the public to contribute their own historical spatial knowledge through spatial storytelling. Together, these activities can promote the long-term sustainability and success of historical data crowdsourcing projects.

Spatiotemporal patterns of street-level solar radiation estimated using Google Street View in a high-density urban environment

This study presents a method for calculating solar irradiance of street canyons using Google Street View (GSV) images and investigates its spatiotemporal patterns in a high-density urban environment. In this method, GSV images provide a unique way to characterize the street morphology from which the diurnal solar path and solar radiation exposure can be estimated in a street canyon. Verifications of our developed method using free-horizon HKO observations and street-level field measurements show that both the calculated clear-sky and all-sky solar irradiance of street canyons well capture the diurnal and seasonal cycles. In the high-density urban areas of Hong Kong, we found that (1) the lowest monthly averaged solar irradiations in winter are 6.6 (December) and 4.6 (February) MJ/m2/day, and the highest values in summer are 17.3 (July) and 10.8 (June) MJ/m2/day for clear-sky and all-sky calculations, respectively; (2) The spatial variability of solar irradiation is closely related to sky view factor (SVF). In summer, the irradiation in a low-rise region (SVF≥0.7) on average is about three times that in a high-rise region (SVF≤0.3), and they differ by about five times in winter; (3) Street orientation has a significant impact on the solar radiation received in a high-density street canyon. In general, street canyons with West-East orientation receive higher solar irradiation during summer and lower during winter compared to those with South-North orientation. The generated maps of street-level solar irradiation may help researchers investigate the interactions between solar radiation, human health and urban thermal balance in high-density urban environments.

A parametric study of the effect of roof height and morphology on air pollution dispersion in street canyons

We investigate the effect of conventional pitched roofs on ventilation and pollution in street canyons using Computational Fluid Dynamics and a parametric approach. We studied parallel street canyons with several street morphologies, created by assigning a set of streets with pitched roofs, and varying their pitch and arrangement for three different height-to-width aspect ratios. The distribution of flow properties and pollution concentrations within the street canyons are examined and the effect of different parameter combinations is assessed. We find the relationship between these properties and the street morphology to be complex and case specific.For most morphologies, the pitched roofs lead to higher average pollution concentrations, and in some cases to pollution hotspots near emission sources especially on the leeward side. The pitched roofs are rarely beneficial to ventilation of the street canyons, but a few roof arrangements lead to reduced concentrations on the windward side. Roof slope is shown to significantly relate to both average pollution concentrations and their distribution inside the street; in some street geometries more than others. The results have implications for pedestrian and residential pollution exposure, and for conservation of building facades on historical buildings.

Street morphology and severity of road casualties: A 5-year study of Greater London

ABSTRACTBuilt environment factors, especially street-scale design and traffic casualties, are intrinsically interlinked. Starting from Alker Tripp's seminal ideas about city design, street morphology, and accident risk, this article summarizes results from an increasingly sophisticated line of enquiry at the boundaries between transport geography, network modeling, urban geography, and planning. It goes on to specify what we believe to be the most comprehensive study yet, based on five years' worth of road casualty data from London; GIS data on street morphology and physical features captured at a street-link unit of analysis; socio-economics and other determinants of accidents; and individual data about casualty victims. We test hypotheses about links between urban morphology and casualty severity using multi-level models with individual victim attributes at level-one, street-link morphology attributes (various measure of network connectivity) at level-two, and neighborhood descriptors at level-three.Results indicate that street-level morphology and design (expressed in terms of betweenness, divergence ratio, and hull radius), together with traffic volume and physical features of streets are all significantly associated with odds of “Killed and Seriously Injured” (KSI) causality incidents. We find the strongest evidence yet recorded that London's 20-MPH speed-restricted residential zones reduce the incidence of KSI; while neighborhood-level factors such as population density, deprivation of living environment, and access to services are also significant predictors of KSI indicating that selective urban territorial enclosure can save lives.

The grid as algorithm for land use: a reappraisal of the 1811 Manhattan grid

ABSTRACTManhattan’s 1811 street grid defined the spatial framework for urbanization. Existing scholarship, however, has not empirically examined its role in determining land-use geography. By mid-nineteenth century, New York City had grown substantially into its street system, but had not yet instituted comprehensive zoning regulations. We explore interactions between the grid’s morphology and land-use placement on the street in a generally unregulated environment, comparing patterns in the city’s pre- and post-grid halves. Deploying new GIS data and methods, we complement existing interpretations showing that the grid guided Manhattan’s development towards mixed-use commercial and residential avenues with residential and industrial cross-streets. We demonstrate that one set of locational logics drove these patterns pre- and post-grid. The grid amplified the morphological parameters of land use, identified as street connectivity, length, and width. Connectivity, determined by block dimensions, constituted the most critical factor. Lastly, we suggest that our findings and methods on the interactions between street morphology and land use are relevant to other cities, both for historical research and contemporary planning practice.

An investigation on the effect of street morphology to ambient air quality using six real-world cases

Street canyons are vulnerable to air pollution mainly caused by vehicle emissions, which are therefore closely related to pedestrians’ health. Previous studies have showed that air quality in street canyons is associated with street morphology, though the majority of them have focused on idealized street models. This paper attempts to investigate the relationship of street morphology to air quality for 6 irregular real-world cases selected from America, Europe, and China, i.e. Manhattan, Paris, Barcelona, Berlin, London and Nanjing. Each street is analyzed as a set of slices to propose a couple of morphology indices for quantitatively assessing the actual street morphology. Pollutant transport rate of mean flows and turbulent diffusion, net escape velocity and age of air are obtained from computational fluid dynamics (CFD) simulations to assess the ventilations and pollutant dispersion within street canyons with a parallel approaching wind. The results show that the street morphology characteristics, including the street width, lateral openings and intersections, are closely related to the air flows in street canyons. The air quality improves with a decreasing aspect ratio of central street owing to a larger vertical exchange through the street roof, which suggests an open central street is of better air quality. The lateral openings and intersections of streets have important effects on the air flows in street canyons, and the effects are particularly pronounced when the street widths are similar. The street continuity ratio indicates street continuity. It relates to the openings and the symmetry of a street and impacts on the air flows and pollutant dispersion through the lateral openings of the central street. The street spatial closure ratio is determined by the street continuity ratio and the aspect ratio of the central street. When the aspect ratio of central street is not excessively high, higher values of street continuity ratio and spatial closure ratio can lead to a stronger channel flow in street canyons and improve the air quality. The octagon intersections are favorable for air flowing through the lateral openings and improve the channel flows. The oblique intersections can also greatly improve the street ventilations, mainly due to the enhanced air flows through the lateral openings and the increased turbulent diffusion through the street roofs.

Contributing to WUDAPT: A Local Climate Zone Classification of Two Cities in Ukraine

Local climate zones (LCZs) divide the urban landscape into homogeneous types based on urban structure (i.e., morphology of streets and buildings), urban cover (i.e., permeability of surfaces), construction materials, and human activities (i.e., anthropogenic heat). This classification scheme represents a standardized way of capturing the basic urban form of cities and is currently being applied globally as part of the world urban database and portal tools (WUDAPT) initiative. This paper assesses the transferability of the LCZ concept to two Ukrainian cities, i.e., Kyiv and Lviv, which differ in urban form and topography, and considers three ways to validate and verify this classification scheme. An accuracy of 64% was achieved for Kyiv using an independent validation dataset while a comparison of the LCZ maps with the GlobeLand30 land cover map resulted in a match that was greater than 75% for both cities. There was also good correspondence between the urban classes in the LCZ maps and the urban points of interest in OpenStreetMap (OSM). However, further research is still required to produce a standardized validation protocol that could be used on a regular basis by contributors to WUDAPT to help produce more accurate LCZ maps in the future.

The Median Picnic: Street Design, Urban Informality and Public Space Enforcement

Medians or central reservations have received scant attention in the vast literature on the history, morphology and design of streets, and are rarely considered as places where people can gather. They are mostly conceived as safety barriers, traffic-calming elements or visual features on multi-way streets. However, by focusing on a case study from Berkeley, California, this paper demonstrates how medians transform into active, informal gathering places despite the presence of prominent prohibitory signage and apparent safety risks. The paper explains how the ‘unlawful’ activity of sitting on the median, or ‘picnicking’ in this instance, is selectively condoned by the City of Berkeley to suit its own liberal image, and because of the commercial interests at stake, underscoring the political dimension in the production of public space. The paper thus engages a discussion of the concepts and practices related to street design, urban informality and public space enforcement, for which the ‘median picnic’ stands as a striking example.

Street morphology and its effect on pedestrian movement in historical Cairo

This article reports on a study that uses a three-dimensional method of analysis to investigate street morphology and its effect on pedestrian movement in historical Cairo, Egypt. The author explains that historical sites are a way to better understand a city's cultural development. The sites develop as a consequence of overlapping multiple layers of historical periods. The study uses El-Muize Street inside Fatimid Cairo as a case example with three components: evolution along different historical eras, defined boundaries, and a variety of sociocultural activities. Experiments were performed to understand which cross-section data correlated with pedestrian movement flow and densities. These experiments are compared with the field survey data of pedestrian counting, analysis of the number of entrances, and the speed of movement for different users. The field survey method was used to trace people movement, followed by transforming the data into the GIS system and correlating the results with the street cross-section analysis. The author introduces 3D analysis for space syntax, based on the ratio between average heights to the street width. The author concludes that street morphology can affect the pattern of pedestrian movement and land use distribution.

Tracking ethno-cultural differences: the Lagos steam tramway, 1902–1933

The Lagos steam tramway project (1902–1933) is examined against the background of British colonial town-planning policy in early twentieth-century Nigeria, with reference to the effects of its layout and services on Lagos's street morphology and ethnic tapestry. Drawing on contemporary evidence regarding colonial plans as well as local physical and social circumstances, the article shows that the tramline was used by the British colonial authorities to reinforce a pre-existent informal residential segregation in Lagos between the indigenous and the expatriate populations. By examining both social and morphological structures in order to understand the political and ethno-cultural implications of the tram, this article contributes to the recently growing literature on the history of European modes of planning outside Europe. In this literature, interdisciplinary in its character, sub-Saharan Africa has relatively limited representation.

America's new downtowns: revitalization or reinvention?

Contents: Preface Introduction The Downtown Imperative and the Need for Comparative Studies1. The American Downtown: The Myth of a Golden Age 2. The Evolution of the American Downtown, 1850-2000 3. The Downtown Stage: Physical Site, Street Morphology, and Civic Space 4. Traditional Downtown Functions: Offices, Retailing, Hotels, and Convention Centers 5. Downtown Expands: Major Attractions, Historic Districts, Residential Neighborhoods, and Transportation Innovations 6. Ranking Downtowns: Toward a Model of Spacial Organization Notes Bibliography Index