Densification Of Cities Research Articles

Nature-based solutions across spatial urban scales: three cases studies from Nice, Utrecht and Milan

A holistic vision for urban sustainability looks at the city as an integration of energy, environment, mobility, urban design, new technologies and, most importantly, ‘people and nature’. In this article, the aim is to shed light on the role of nature-based solutions (NBS) towards addressing climate change crisis and tackling a variety of socio-ecological and urban biodiversity challenges. The paper claims for more evidence-based frameworks to understand the economic, social and environmental benefits of NBS and to promote their inclusion in urban policies. First, and most importantly, the role of NBS in shaping urban planning as a result of expansion and densification of cities is reviewed. Second, the co-benefits generated by NBS within the social and cultural regeneration of cities are reflected upon. Lastly, case studies are given from Nice, Utrecht and Milan in order to showcase those cities’ spatial strategies to implement NBS through different scales. The article discusses the role of NBS in addressing climate challenges and emphasises the need for collaborative stakeholder engagement in their implementation. Spatial, governance and temporal challenges related to NBS implementation are identified, underscoring the complexity of integrating NBS into urban environments. The article concludes by advocating for systematic integration of green and blue infrastructure and NBS into urban planning, emphasising the importance of considering socio-cultural elements alongside environmental benefits.

Recent Dynamics of Suburban Advancement and Building Densification in Relation to Landslide Exposure in the Main Cities of North-East Romania

We live in a complex and highly dynamic risk society, and given the massive environmental changes, exposure to hazards has become a critical concept that is part of all risk assessments made from a spatial perspective. In urban studies, evaluating exposure to different risk phenomena influences targeted policies and planning that can shape cities while making them safer. As in other post-socialist countries, in Romania, cities have had a highly divergent recent evolution, including processes such as urban shrinkage, the suburban advancement of cities, and urban sprawl. Focusing on seven cities from the North-East Region of Romania, the current paper is an exploratory study regarding the dynamics of exposure to landslides in relation to suburban advancement and densification of cities. Using the official statistics, available GIS databases and information based on satellite images illustrating urban land use changes in the last 20 years, the paper includes a general overview of the overall evolution of urban areas against landslide probability, followed by a more in-depth assessment of specific areas that were subject to functional change and currently include buildings that are susceptible to be affected by landslides. The results and conclusions converge towards the idea that the identified exposed areas, where actual ground movements are currently registered, need special attention from experts and authorities to identify and manage risks. The significance of our findings is underscored by their potential to inform and guide more effective territorial management and urban land use planning strategies.

Should Danish building regulations legalise basement dwellings? – Consequences for daylight and view out investigated through case studies

Densification of cities is ongoing for sustainability purposes, but it has consequences for daylight availability in dwellings and the view out. Despite 'comparable conditions', national daylight and view-out regulations differ between Nordic countries, particularly regarding allowing dwellings below ground level. Two case studies investigate daylight and view-out access in modelled basement dwellings through simulations of daylight autonomy and renders of view-out content. Results indicate that basement dwellings can meet daylight and view-out access requirements in suburban, low-rise neighbourhoods but cannot meet the requirements in medium- to high-rise urban contexts. This study will contribute to future political decisions on national building regulations in Denmark and may influence future decisions on urban planning and building development.

Does the High-Rise Building Typology meet the needs for City Densification? The case of Tirana, Albania

The first high-rise building ever in Tirana and Albania was built during the 70-s. This was Hotel Tirana or “15-kateshi” as it was nicknamed. At that time, Tirana was building not more than six floors high due to limitations in finances, technology, as well as seismic regulations. Hotel Tirana was an exception for ideological and symbolic reasons of the regime. After the ‘change’ of the early 90-s and the return of the market economy, several private construction companies came up by developing ‘tower’ typology buildings of 7-9 floors. In the second decade of transformations, the municipality developed several international architectural competitions, including a masterplan for the city centre (2003) and other specific construction sites, mainly for strategic high-rise building purposes. During these years, Tirana was densified by tripling its population thanks to a typology of towers of 9-11 floors. There has been a lot of criticism of the respective municipal decision-making procedures, allegedly related to the politicization and corruption of the verticalization and densification process via control of the building permissions system

Shadowing pathology on diaphragm walls investigation

Nowadays, the densification of cities requires the multiplication of underground infrastructures like car parks and metro stations. It is in this context that has been established for 70 years now, the diaphragm wall technique. The construction works follow complex implementation operations that can generate some defects and cause the appearance of imperfections. Among these imperfections, shadowing pathologies is the main subject of this study. The objective is to better understand the different operations with the intention in explaining the formation of the pathology.An experimental study is presented to answer some questions related to the concrete. Thanks to a laboratory prototype called Beta Tank, two complementary campaigns were conducted. Using different exfiltration outcomes, and by varying the cementitious material, it was possible to recreate the shadowing pathologies. The results found from the experimental campaigns allowed identifying potential causes of the anomalies and helped in proposing some recommendations for the foundation materials and techniques.

Sources of contamination in sediments of retention tanks and the influence of precipitation type on the size of pollution load

Densification of cities and urban population contributes to increased runoff and suspended solids and alteration of the urban water cycle. Nowadays, Blue-Green Infrastructure is promoted to increase a city’s resilience to floods; however, stormwater drainage systems, supported with retention tanks are still important in protecting urban areas against floods. Sediment accumulation in stormwater infrastructure relates to an issue of pollutants such as heavy metals, nutrients etc. Research on the origin of the pollutants associated with the suspension and ultimately sediment accumulated in sewage can bring new insights about processes in urban catchment areas. This is the first study, which is focused on the analysis of stable carbon and nitrogen isotopes in bottom sediments collected from municipal retention tanks to verify the origin of the deposited pollutants immediately after pluvial floods. The research was additionally extended with water quality analyzes immediately after three types of weather: a dry period, typical precipitation (< 30 mm) and torrential rainfalls (2 events with daily precipitation over 30 mm which caused pluvial flooding of the city area). Analyses of sediments indicated that the main source of carbon and nitrogen in the bottom of the retention tanks had been brought with stormwater runoff from the city area. Organic nitrogen fertilizers appeared to be the main source of nitrogen, while the sources of organic carbon were mixed: C3 land plants, wood, and oil. Additionally, it was found that torrential rainfall caused a 23-fold increase of N-NO3 concentration, a sevenfold increase of P-PO4 concentration, and an over fivefold increase of concentration of organic matter, in comparison to typical precipitation.

City densification and temporal dynamics of traditional inner core of Ibadan, Nigeria

The conversion of vegetation land cover contributes to the retention of solar radiation in the environment, resulting in the formation of the urban heat island. This study analyses the distribution pattern of urban heat island in the traditional core of Ibadan amidst the rapid urbanization experienced. The remote sensing tool was used to analyse the trend of land surface temperature, normalized difference built-up index, and normalized difference vegetation index for the traditional Ibadan's core between the year 2000 and the year 2020. This reveals that increasing built-up areas will continue to strengthen the effects of urban heat island in the traditional core of Ibadan, while vegetated land covers will weaken the effects of urban heat island. This is because anthropogenic activities resulting from rapid urbanisation has adversely altered the natural landscape in the traditional core of Ibadan. This alteration manifests in converting vegetation land covers into physical developments and other impervious surfaces by the increasing urban population. Thus, increasing the land surface temperature. The maximum average land surface temperature of 35.34℃, 36.62℃ and 31.86℃ were record for the years 2000, 2013 and 2020 respectively. This study further recommends that urban greening and proper urban planning should be encouraged in the traditional core of Ibadan. Keywords: Land Surface Temperature, Normalized Difference Built-up Index, Normalized Difference Vegetation Index, traditional core, urban heat island

Using plant community uniqueness and floristic quality assessment in management decision-making in an urban park setting

With the densification of cities, it is imperative to identify urban ecosystems that should be protected or restored. We aimed to determine the conservation and restoration needs in a large urban park (1,35 km2) in Quebec City (Canada), based on site history, current species richness, floristic uniqueness, and floristic quality assessment of its diverse ecosystems: forest, swamp, wooded peatland, open peatland, and marsh. We evaluated the cover of all vascular species in 70 plots (400 m2) and assessed 18 environmental variables. We found that forest and swamp plots were the richest while peatland plots were the poorest, with marsh plots showing intermediate values. Ecological uniqueness (LCBD) was not correlated with richness (ρ = 0.17; p > 0.05), with marsh and peatland plots showing the highest and lowest uniqueness, respectively. With a regression tree, we identified canopy openness as the most influential variable explaining plot uniqueness across all ecosystems, especially in the peatland, indicating that future recreational development should be avoided in open ecosystems. By plotting ecological uniqueness (LCBD) with tolerance to disturbance (Mean C) values, we identified areas that could benefit from conservation or restoration, and areas that could sustain future development for recreational use. For each area, floristic composition, site characteristics, and past land-use history were investigated further to identify appropriate actions. The open peatland was identified as the main conservation priority, but actions will be needed to limit rapid tree encroachment. Three marshes were identified as areas that would floristically benefit from restoration actions. Still, since they also act as natural retention basins hosting species adapted to the soil conditions, we suggested monitoring the expansion of exotic and invasive species. Approaches developed and lessons learned from this project will serve as guidelines for municipalities aiming to implement a restoration and management plan in urban parks.

The Residual Spaces of Developmental Urbanism as Opportunity for Green Cities and Improvement of Human Wellbeing

City densification and greening are two priority urban-policy objectives, for the coming years, aimed at making cities more resilient to climate change, slowing the spread of urbanization and improving the quality of life in cities. These are sometimes contradictory objectives that require fine and deep analysis to create approaches and methods that combine them. The most recent research has presented so-called small urban green spaces (SUGSs) as a viable alternative to achieve this double objective. This was the starting point of this research, which used GIS digital analysis and microscale fieldwork to study the possibilities of greening an excessively dense and low-quality urban space in the city of Pamplona (Spain). The results thereof showed that the urban structure of this neighbourhood contains a large number of small spaces with no specific use or function—residual, surface and vertical spaces—and that are simply undefined remnants between buildings and streets, or party walls that were never built. Only these surface spaces occupy a total area that is twice the size of the existing green spaces. Based on these results, this work explores the possibility of increasing the green areas of the neighbourhood through new SUGSs and the creation of a green corridor that increases environmental and social connectivity and the quality of life in the studied space.

Environmental noise and densification of cities - a paradox?

Densification of cities is used because of numerous benefits and fits well with sustainable development. Densification can however lead to disadvantages, especially related to environmental noise. In this paper, we ask: is it possible to restrict disadvantages by balancing out these with benefits? Access to quiet areas in cities plays an important part here, due to benefits related to well-being and health for inhabitants. We will give an overview of Norwegian guidelines on environmental noise and how these are implemented. We look at the situation from the Norwegian Public Roads Administration's viewpoint and include the experiences from a consultant company. We present projects situated in Norway, a large country with a relatively low population density compared to most other European countries. However, access to quiet areas isn't optimal in the largest cities, which leads to problems related to environmental noise and densification. Our experience is that it's crucial to include noise assessment in the early stages of planning. Together we need to find a balance, where new roads and new dwelling areas can be realised without more negative than positive aspects. The final goal must be, that there is no paradox!

Thermal Effects of Vertical Greening in Summer: An Investigation on Evapotranspiration and Shading of Façade Greening in Vienna

Global urbanization is advancing, and with it, the densification of cities. Due to increased sealing of open spaces and the re-densification of existing urban settings, green spaces in the city are becoming scarcer. At the same time, greening within the urban fabric is known for its positive effects on the environment and decisively counteracts the urban heat effect. This study deals with the benefits of green façades for the environment as a cooling measure. Two façade greening systems, one trough and one cassette system, consisting of curtain wall elements with a basic metal structure, installed at a south-facing outdoor wall of a school building in Vienna, Austria, were taken under metrological examination. In order to evaluate the cooling effect caused by evapotranspiration, the amount of water evaporated was calculated using the difference of inflow and outflow. Furthermore, the surface temperatures of the greened and non-greened walls were measured to display the influence of the interaction of shading and evapotranspiration on the surrounding microclimate. The investigated vertical greening system with an area of 58 m2 has an average evaporation capacity of 101.38 L per day in the summer. The maximum surface temperature difference was measured to be 11.6 °C.

Strong relationships between urbanization, landscape structure, and ecosystem service multifunctionality in urban forest fragments

Urban forest fragments are highly multifunctional and provide many ecosystem services to people. However, the expansion and densification of cities is threatening this particular type of urban forest, resulting in further fragmentation, degradation and a change in forest function. Understanding how urbanization affects urban forests fragments and the multiple ecosystem services they provide is important for the creation of livable cities. We used an urban-to-rural gradient in Maple Ridge, Canada, to explore relationships between urban forest structure, urbanization, surrounding landscape structure, and the supply of eight different ecosystem services, including merchantable timber, carbon storage, flood control, food (berries), non-native shrub control, cultural use, and habitat provision. We found that the supply of multiple ecosystem services was higher at the rural end of our gradient and that forest fragments spaced closer together showed strong negative associations with most services. Crucially, forest fragment size had very weak effects on most services, emphasizing the importance of conserving small urban forest fragments with large trees. We also identified key tree genera, including Picea and Thuja, that could be retained or planted in urban forests to maximize individual services and multifunctionality. Our results highlight the potential for strategically managing urban landscapes to maintain forest fragments and enhance their ability to provide ecosystem services and multifunctionality. Our findings are relevant to inform urban conservation and greening strategies in cities around the world that are currently expanding into surrounding forests or losing greenspace through densification.

Do we have enough recreational spaces during pandemics? An answer based on the analysis of individual mobility patterns in Switzerland

Densification of cities threatens the provision of public open space for people living in and around cities. The increasing evidence of the many benefits of recreational walking for physical and mental health during the COVID-19 pandemic has highlighted an urgent need for fostering the availability of public open space. In this context, urban planners need information to anticipate recreational needs and propose long-term, resilient solutions that consider the growing demand driven by increasing urban population and intensified in times of crisis such as the recent pandemic. In this paper, we harness the unique large MOBIS:COVID-19 GPS travel diary data on mobility behaviour collected during a normal baseline period and during the first wave of the Covid-19 pandemic in the Canton of Zurich Switzerland. We estimate a sufficiency rate that allows to geolocate locations where the demand for public open space is higher than the available offer. In a second step, we explore if preference patterns for recreational areas have changed during the pandemic. Results indicate that the main cities and important towns in the case study area are saturated by current demand, and that the pandemic has amplified the problem. In particular, urban dwellers look for tranquil areas to recreate. Such information is crucial to guide decision-making processes for planning the cities of the future.

Global urban sprawl containment strategies and their implications for rapidly urbanising cities in Ghana

Cities in Sub-Saharan Africa (SSA) have so far failed to sustainably address urban sprawl and its ramifications. Meanwhile, the projected increase in the urban population in the cities in SSA is expected to exacerbate the situation, making the search for sustainable solutions an urgent one. In this review, we contribute to the search for sustainable urban sprawl containment strategies through the lens of policy transfer theory. Using Ghanaian cities as examples, we argue that ‘successful sprawl containment strategies’ implemented in developed countries in the Global North can be adapted to help address sprawl in cities in SSA. In particular, the review found that strategies that promote city densification and direct the physical growth of cities are suitable for urban sprawl containment in highly urbanised cities in Ghana. Strategies that preserve farmlands and green spaces are recommended for municipalities and districts that are predominantly rural but urbanising rapidly. While we have limited the discussion to cities in Ghana, the similarities regarding land tenure practices and urbanisation dynamics (including the drivers for urban sprawl) across cities in SSA make the findings applicable to many other cities within the sub-region. However, the success of the sprawl containment strategies is tied to the ability of city authorities to address the land tenure conflicts, strengthen planning institutions, and collaborate in the efforts to contain urban sprawl. Recommendations for addressing these intractable urban planning challenges are provided in the discussion.

Exploring the design, quality and use of communal areas in apartment developments

ABSTRACT Population growth and urbanisation are contributing to the densification of cities globally, including a proliferation of apartment developments. While many developments include shared spaces and facilities, little is known about their design, quality or use. Using a novel desktop audit approach, we objectively identified communal area design features and examined their association with residents’ use of communal areas in apartment developments (n = 113) across Perth, Melbourne and Sydney. For residents with outdoor areas (n = 1039), use was associated with ten features, including greenery, pools and seating. For residents with indoor areas (n = 283), use was associated with four features, including a ‘green’ outlook and ground floor location. Features were combined into quality scores, where each unit increase was associated with greater odds of outdoor (OR = 1.37, 95% CI = 1.28–1.47) and indoor (OR = 1.91, 95% CI = 1.52–2.42) area use. These results suggest that the delivery of high-quality communal areas can encourage use, which in turn, may have implications for residents’ social opportunities and outcomes. The findings also have policy and design implications, suggesting that the provision of communal space alone may not be enough to encourage use without the design features or amenities that appeal to residents.

Data-driven placemaking: Public space canopy design through multi-objective optimisation considering shading, structural and social performance

In the context of ongoing densification of cities and aging urban populations, public spaces are a crucial infrastructure to support the physical and mental wellbeing of urban residents. The design of public space furniture elements is often standardised, and not considered in relation to environmental conditions and mechanisms of social interaction. This article presents a digital workflow to generate site-specific designs for shaded public seating, considering the relationships of local public places to their surroundings. A strategy for customised and site-specific design is developed through the use of multiple software tools, employing evolutionary algorithms and multi-objective optimisation. The method is applied to a small public space canopy prototype installed within a public housing estate in Hong Kong, incorporating additional criteria to achieve a low-cost and light-weight structure. Through multiple stages of refinement and optimisation, a material, structural and social performance-driven outcome was achieved that creates a shaded space for public seating, people watching and social interaction. As part of a larger research agenda exploring architectural form-finding and environmental psychology, the project represents potential new applications in the emerging field of socially driven computational design.

The role of building morphology on pedestrian level comfort in Northern climate

Due to the rapid densification of cities, improving outdoor comfort is becoming increasingly important. To address this need, the current study introduces a methodology to evaluate outdoor comfort in the proximity of typical buildings in Tallinn, Estonia. The microclimate simulation software ENVI-met was employed to investigate the outdoor comfort conditions. The research outcomes show that the building's form, height, density, and orientation change consistently the pedestrian comfort around the buildings. The findings suggest that the integrated analysis of different building morphologies, massing, orientation, and their influences on the surrounding microclimate, thermal, and wind comfort are important.

An assessment framework for safeguarding public values on mobility platforms

Urbanites increasingly turn to digital mobility platforms to make use of means of transportation and to plan and book journeys. While these platforms can contribute to making urban travel more sustainable and efficient, they can also lead to governance challenges and have negative external effects, raising questions about how public values can best be safeguarded. In this article, public values are defined as normative concepts that describe both the impact on and democratic control of an affected public. This article aims to initiate a more structured discussion about platform urbanism, specifically how and to what extent public values are incorporated in platform design and operation in the realm of mobility. It introduces an assessment framework for mobility platforms that was developed as part of a transdisciplinary research project in the Netherlands. This framework is grounded in two academic debates regarding 1) the rise of platform urbanism and 2) new forms of mobility that accompany the densification of cities. The paper refers to the mobility pilots Kutsuplus, UbiGo and Whim to illustrate how the safeguarding of public values can be evaluated. In the concluding section, the paper discusses some ways in which the assessment framework can be used for future research, for instance through scenarios.

Anatomy of density: measurable factors that constitute urban density

Serious concerns about global warming have been translated into urgent calls for increasing urban densities, as higher densities are associated with lower carbon emissions from both vehicles and buildings. However, attempts at effective densification have generally failed and urban densities continue to decline in cities across the world. Calls for densification without making room for it have resulted in serious housing supply bottlenecks in many cities and have rendered their housing unaffordable. If affordable densification is to be successful, it is necessary to understand the factors that constitute urban density. A novel way is presented for factoring the average density of cities into constituent factors—three or seven factors—that when multiplied together reconstitute urban density. This factoring methodology is presented together with the preliminary measurement of these factors in 10 cities in 10 world regions. This approach allows, for the first time, a clear understanding of how different cities acquire their density: Hong Kong gets its density from building height; Kinshasa from crowding; and Dhaka and Bogotá from residential coverage. This anatomy of density offers a new outline for a comprehensive strategy for city densification: one that addresses each and every one of the factors that constitute urban density. <em><strong>Practice relevance</strong></em> Urban density is usually defined as the ratio of the total population of a city and its total area. This is the most appropriate single metric for measuring progress in densification in cities and is now a central objective of the global climate change agenda. However, this metric is rather crude and often hides more than it reveals. The anatomy of density offers a new, simple method for factoring urban density into its constituent factors that when multiplied together reconstitute urban density. This approach offers city leaders and urban planners a new way to consider and develop comprehensive policy options and strategies for city densification that addresses each and every one of the factors that constitute urban density and the tradeoffs between them.

Learning from the gardeners of the oldest community garden in Seattle: Resilience explained through ecosystem services analysis

Urban agriculture, which includes community gardens, provides ecosystem services but is continuously threatened by the densification of cities. Picardo Farm is the oldest community garden in Seattle. Its success and popularity inspired the municipality of Seattle to develop a city-wide public program called the P-Patch Community Gardening program. We evaluated the perceptions of Picardo Farm gardeners about the benefits provided by the farm and the reasons why this community garden is so resilient. Gardeners were asked three open-ended questions and their responses were evaluated for recurring keywords regarding ecosystem services. We found that gardeners’ perceptions of ecosystem services vary, and they often underestimate ecosystem services related to regulation. We identified seven key topics from gardeners’ responses: a sense of community, placemaking, food, health, place attachment, nature, and education. Furthermore, our results indicate that, in order to achieve resilience, community gardens require public institutions to build and empower cohesive communities of gardeners and gardens need to be placed in urban areas suitable for agricultural use.