Dense City Research Articles

Nature’s Neighborhood: The Housing Premium of Urban Parks in Dense Cities

Urban parks, a core component of urban landscapes, play a crucial role in mitigating the negative effects of rapid urbanization and achieving sustainable urban development. In densely populated urban environments, providing urban parks fairly and efficiently, taking social preferences into account, is an important challenge. In this regard, we take Hangzhou, China, as an example and use a hedonic pricing model with a difference-in-differences estimator to test the effect of different types of urban parks on housing prices, quantify their respective economic values, and reflect homebuyers’ preferences. The findings indicate that the construction of new urban parks leads to an overall increase in the value of the surrounding real estate to some extent. Specifically, the construction of comprehensive parks and large parks significantly enhances the value of nearby housing, while proximity to new medium-sized parks also results in a housing price premium, albeit to a lesser extent. In contrast, community parks and specialized parks have a less significant impact on housing prices. These findings provide valuable insights for equitable urban development and planning, optimizing the allocation of urban parks and determining investment priorities for different types of parks to enhance the sustainability of the urban environment and human well-being.

Acoustic Natural Ventilation Openings - OVNA : How to get rid of the impossible choice between too much heat inside or too much noise !

Due to global warming, summer comfort in buildings is a prime issue, and so is indoor air quality. Natural ventilation is encouraged by "low-carbon" approaches to cool the buildings and reduce air-conditioning. However, remaining free constructible areas in dense cities are mainly noisy, and the inhabitants should not be forced to choose between too much heat inside or too much noise ! The first step is to anticipate buildings' façades " eligibility for natural ventilation through opened windows ", depending on their exposure to the forecoming noise sources. Since 2015 LASA has been carrying R&D on " Acoustic Natural Ventilation Openings - OVNAs" which aims to bring great amounts of fresh air in the buildings, for cooling and ventilate them without allowing noise inside ! It implies to develop accurate exposure models for "noise peaks" which cause sleep or work disturbances, and anticipate the required noise reductions for each windows. On the basis of this work, and an ongoing PhD at LASA, we seized the opportunity to build two OVNA prototypes and to carry out listening sessions and acoustic/thermal measurements. Theses experiments have enabled LASA to confirm the OVNA's performances (sound attenuation, etc.) and improve the modelisation and assessing methods.

How to get high-rise residential design to respond road traffic noise

Rapid urbanization causes acute contradictions of road traffic noise on residents' health. Although many works have been done in this field, specific investigations of how to get a design of residential area to correspond road traffic noise is still limited, especially in a high population dense area. This paper, therefore, focused on high-rise residential blocks, researching relations between design variables and distribution of road traffic noise. In the study, a typical high population dense city, Shenzhen was employed as study case. Based on noise map simulation, design element, block layout, design of individual buildings was proved important in traffic noise impact. The results discovered that the noise reduction effect is relatively significant when the building setback is within 30 - 40 meters of setback curb. To minimize traffic noise impact, flexible layout of board point perimeter type might play an important role. Lowering building heights with increasing the number of building rows, two-story podiums around high-rise buildings, and the addition of balcony railing plate could result in significant noise reductions. Focusing on design elements, this work developed an overall evaluation to improve acoustic environment of high-rise residentials based on noise map simulation, and provided significant contributions in responding road traffic noise.

Linking joint exposures to residential greenness and air pollution with adults’ social health in dense Hong Kong

Despite the growing recognition of the impact of urban environments on social health, limited research explores the combined associations of multiple urban exposures, particularly in dense cities. This study examines the interplay between greenspace, air pollution, and social health as well as the underlying pathways and population heterogeneity in Hong Kong using cross-sectional survey data from 1977 adults and residential environmental data. Social health includes social contacts, relations, and support. Greenspace used street-view greenness (SVG), park density, and the normalized difference vegetation index (NDVI). 100-m daily ground NO2 and O3, indicative of air pollution, were derived using a spatiotemporal deep learning model. Mediators involved physical activity and negative emotions. Main analyses were performed in a 1000-m buffer with multivariate logistical regressions, stratification, interaction, and Partial Lease Square - Structural Equation Modelling (PLS-SEM). Multi-exposure models revealed positive associations between park density/SVG and social contacts, as well as between SVG and social relations, while O3 was negatively associated with social relations/support. Significant moderators included age, birthplace, employment, and education. PLS-SEM indicated direct positive associations between SVG and social contacts/relations and significant indirect negative associations between NO2/O3 and social health via negative emotions. This study adds to urban health research by exploring complex relationships between greenspace, air pollution, and social health, highlighting the role of the environment in fostering social restoration.

A benchmarking analysis of sunlight and daylight availability in a highly dense urban area in southern China

The availability of daylight and sunlight in dense cities has increasingly received attentions. This article presented a benchmarking analysis of daylight & sunlight availability in six urban residential layouts at Guangzhou in southern China. As representatives of old or new towns, these layouts were achieved using local regulations. The benchmarking system was built based on an urban building under various levels of obstruction (horizontally infinite length). Daysim (Radiance) and T-sun were applied to calculate daylight illuminance and sunlight hours at building facades, respectively. Some findings were achieved as follows: 1) For sunlight availability, significant effects of urban layout and orientation can be found in both towns. Most layouts achieved similar sunlight hours as an urban building with high and heavy obstructions, while several southeast-oriented and southwest-oriented layouts had the values like a building with the medium obstruction. No clear differences of sunlight hours can be found between southeast and southwest orientations. 2) For daylight availability, most buildings in both towns had similar frequencies of proper vertical illuminance as an urban building with the medium obstruction. However, the frequencies of excessive vertical illuminance significantly varied in layout, façade position, and orientation and corresponded with the values of an urban building with different obstructions. Effects of layout were found to be clear at low and middle façade positions, while significant effects of orientation were only found at higher façade positions. 3) Generally, a daylighting analysis using the dynamic climate-based model could achieve more practical results than the approach of sunlight hours.

Multiscale Analysis of Pedestrian Crossing Distance

Problem, research strategy, and findings Crossing distance is considered a factor in both pedestrian safety and behavior. However, it has seldom been quantified within or across entire cities or related to walking outcomes. Combining data encoded in OpenStreetMap and drawn from high-resolution satellite imagery, we measured formal pedestrian crossings throughout a dense European city (Paris [France]), a dense American city (San Francisco [CA]), and a less-dense, more car-centric American city (Irvine [CA]). This granular approach—covering roughly 49,000 total crossings—identified inter- and intraurban spatial patterns in the distribution of pedestrian crossing distance, including clusters of long crossings that likely deter walking and increase its risk. By overlaying recent pedestrian–vehicle collisions on these novel data sets we found that longer crossing distance correlated with increased likelihood of collisions, raising the salience of traffic-calming interventions. Takeaway for practice Quantifying pedestrian crossing distance at the scale of entire municipalities empowers transportation planners to identify pedestrian-hostile crossings (individuals and clusters), add context to collision trends, and geographically target locations for traffic calming. These cases collectively demonstrate how the increasing prioritization of the automobile in city planning quantitatively changes (and degrades) the pedestrian environment, as well as how low-tech investments, such as sidewalk extensions and refuge islands, can mitigate these trends.

Assessing urban waterfront public space service quality using importance performance analysis (IPA)

The urge for urban public space evolved in increasingly dense cities. Tirtonadi Dam Park is a waterfront-designed urban park located on Bengawan Solo riverbank area. To support the activities, adequate infrastructure must be provided. The objective of this study was to assess Tirtonadi Dam Park's service quality as an urban public space and suggest methods to improve it to promote local communities' economic development. The variables—infrastructure, access & linkage, comfort & images, use & activity—were evaluated and compiled into 16 indicators. Based on user perceptions, Importance Performance Analysis (IPA) was employed to determine the performance and importance levels of predetermined variables. The findings demonstrated that vegetation, infrastructure for the disabled, and drainage and water systems all dropped into the "concentrate here" quadrant, necessitating further development to enhance quality and add more supporting facilities. Furthermore, the quality of security, environmental cleanliness, pedestrian paths, recreational facilities, informal sectors, lighting facilities, and transportation lies in the “keep up the good work” quadrant so that they should be maintained. Enhancing waterfront facilities with leisurely and recreational features can increase the number of visitors. Improving urban areas and incorporating the surrounding communities in all phases of development will be crucial, with the potential to enhance their economic circumstances.

Resilient trees for urban environments: The importance of intraspecific variation

Societal Impact StatementTrees in urban environments provide us with shade, heat mitigation, flood abatement, noise and pollution reduction, pollination, beauty, and much more. However, many of these benefits are strongly connected to tree size and vitality, with larger, healthier trees providing ecosystem services more effectively, which means that selecting the right tree for site and function is crucial in order to gain all benefits from our urban trees.SummaryTrees play a major role in the Earth's biogeochemical processes, influencing soil production, hydrological, nutrient and carbon cycles, and the global climate. They store about 50% of the world's terrestrial carbon stocks, and provide habitats for a wide range of other species, supporting at least half of the Earth's known terrestrial plants and animals. Trees are not only found in forests and other natural ecosystems, but also in urban environments. Most of the human population is concentrated in cities, towns and villages, so urban trees are critical to meet on‐going and future social, economic and environmental challenges. However, many urban tree populations are strongly challenged by a changing climate, outbreaks of pests and pathogens and an urban development with increasingly dense cities and a high proportion of impermeable surface materials. The importance of intraspecific variation needs to be better acknowledged in this context, since poor matching of trees and the local climate and growing conditions can lead to extensive loss of valuable trees. By using the right genetic plant material for the challenging urban environments, a more resilient tree population with a greater diversity and higher capacity for delivering ecosystem services can be gained. Here, we wish to discuss the need to consider intraspecific variation when planning resilient tree populations for urban environments and how seed banks and botanical garden play important roles in efforts to improve the matching of genetic plant material for future environmental challenges. Strategies to enrich urban tree diversity and increase resilience are outlined.

Analysis of Road Traffic Accidents in Dense Cities: Geotech Transport and ArcGIS

Road Traffic Accidents (RTAs) provide a substantial risk to both public safety and infrastructure within severe earthquake zones. This research aims to provide a thorough analysis of the many elements that contribute to RTAs in the area. Although research on RTAs has been conducted in numerous settings, there is a lack of localized research specifically focused on developing countries. Therefore, this study is necessary to address this gap in literature. Our study focuses on examining the distinct issues and elements that are particular to this specific location. The objective is to provide customized solutions that effectively reduce the occurrence of accidents. The objective of this study is to examine the status of RTAs, ascertain the main factors contributing to RTAs, and provide viable approaches to improve road safety. A comprehensive study of data was undertaken, which included the examination of key highways, accident-prone areas, and causes contributing to accidents. Insights were derived by the use of statistical analysis, hotspot mapping, and the categorization of incidents. The results revealed a distressing roadway are afflicted by a significant frequency of accidents, even those occurring on prominent thoroughfares. Excessive speed has been revealed as the primary contributing factor, closely followed by negligence and recklessness. The common factor seen in these events was the insufficient enforcement of traffic regulations. The research highlights several practical consequences. Firstly, it is advised to implement urgent actions such as the upgrading of the traffic database, the adoption of contemporary traffic management software, and the enforcement of rigorous traffic laws. The establishment of a comprehensive centralized database system is crucial in order to enhance the documenting and management of accidents. Furthermore, the use of cost-benefit analysis provides justification for the adoption of traffic calming measures in locations with a high incidence of accidents. Furthermore, the implementation of continuous road safety awareness efforts and the establishment of clear legislative guidelines pertaining to fatal accidents are imperative measures in promoting enhanced road safety.

Urban morphology as a key parameter for mitigating urban heat? – A literature review

Abstract More frequent and intense heat waves, especially in urban centers, represent a growing challenge for urban designers and building planners. In the last five years, extensive research has been undertaken on the relation between urban form, including density, and urban heat phenomena. Dense urban configurations are often considered central drivers of hot microclimates. However, less dense cities easily cause other ecological (e.g. land consumption), functional (public mobility), and socioeconomic (social diversity) problems. Consequently, the current panoply of recommended heat mitigation and sustainability measures constitutes an unclear basis for strategic planning decisions. Thus, this study examines the literature on urban morphology in relation to urban heat events. Around 800 scientific articles and studies are categorized regarding the applied methodology, the studied geographic location, the observed urban form parameters, and the examined thermal parameter. Most identified literature uses traditional field measurement, remote sensing, numerical simulation, or a combination. Air temperature and land surface temperature are the most observed thermal parameters, while the growing number of studies that focus on human outdoor thermal comfort is highly relevant for effective heat mitigation and adaptation. This study suggests that from a scientific point of view, urban morphology measures do not principally carry a paramount role in heat mitigation compared to other aspects, such as vegetation or materialization. Current planning approaches for climate-resilient cities are highly case-specific, where no generally applicable rules or effective recipes regarding urban built form are available.

Utilizing the Urban Education Typology: A Content Analysis of Selected Citations

In the seminal work “But What Is Urban Education?” from 2012, Richard Milner proffered a typology to better represent urban spaces as conceptions of urbanization's evolution. The typology consists of three descriptors, to which each highlights the manner in which population density influences the availability of resources to support culturally diverse learners: urban intensive (large spatially dense cities), urban emergent (large suburbs and mid-sized cities), and urban characteristic (smaller suburbs and some rural areas). In the present study, we used a cited reference search strategy to locate and retrieve 319 articles citing the Milner article. Then, through quantitative content analysis, we characterized the prevalence and utilization of the typology in educational research. Our results indicate that researchers have used Milner's urban typology to frame urban settings and contexts ( n = 227). Moreover, the citation of the typology has consistently increased each year from 2012 to 2020. The majority of authors citing the typology have accepted it as a suitable framework to describe the urban characteristics of their study. Several authors have identified limitations and constraints related to the typology and have adapted, expanded, or rejected the typology. We provide implications to support theory development and empirical evaluation in urban educational spaces.

A novel acceleration approach to shadow calculation based on sunlight channel for urban building energy modeling

Shadow effect among buildings has great impacts on the building energy consumption and the performance of building photovoltaic, and calculating shadows on building surfaces in urban building energy modeling (UBEM) faces challenges of inefficiency, especially for dense urban areas. In this study, a novel shadow calculation approach based on sunlight channel is proposed that can streamline the surrounding environment and accelerate the shadow calculation process. The sunlight-channel algorithm can further accelerate the shadow calculation process by dynamically predetermining the shading surfaces according to the actual solar position. In a real urban context, the proposed approach can accelerate the computation process by over 10 times over the baseline and over 34 times over the non-accelerated method, with a mean absolute percentage error (MAPE) of 1.13% for the total solar radiation. The proposed approach copes well with both large-scale urban models and the complexity of building structures, particularly for urban models with complex changes in building heights. This approach can significantly enhance the computational efficiency in complex urban environments, facilitating an accurate and rapid analysis of the energy consumption and solar potential of buildings in dense cities.

Unravelling the last-mile conundrum: A comparative study of autonomous delivery robots, delivery bicycles, and light commercial vehicles in 14 varied European landscapes

In this study, the growing need for efficient delivery services in the expanding e-commerce sector is addressed, with a focus on real-life consumption data. A comprehensive modelling framework is proposed to evaluate the efficiency of various transportation modes, including Light Commercial Vehicles (LCVs), cargo bicycles, and Autonomous Delivery Robots (ADRs). Utilizing the Google API, delivery destinations are identified, origin-destination matrices are created, and routes are optimized using Google OR-Tools and a capacitated vehicle routing problem solver. The study's robustness is further enhanced by incorporating real-life consumption data, considering diverse European contexts, varying urban scales, traffic patterns, and topographical factors, thus assessing their impact on transportation efficiency. The findings reveal that ADRs are efficient in pedestrian-focused, traffic-limited areas, while bicycles are more effective in dense city centres. This research highlights the necessity of tailoring transportation mode choice to specific urban characteristics for optimal efficiency and consumer satisfaction.Overall, the present study offers valuable insights into optimizing delivery services in different urban settings, providing a significant model for improving last-mile delivery systems. It contributes to understanding how different transportation modes can be effectively integrated into urban logistics, addressing environmental sustainability, operational efficiency, and real-life consumer demands.

The production of Asian public space: the role of the transnational developer

ABSTRACT Accounts of projects generally credit design vision to the landscape architect or architect, relegating the role of the developer to the client. This essay offers an alternative perspective, arguing for the recognition of the Asian developer as an agent of transnational design innovation. While there has been ample discussion of the wealth to be made in the Asian property market, little attention has been paid to the developer’s motives and ambitions beyond economic gain. Through the discussion of two transnational development companies, CapitaLand and Swire Properties, we demonstrate the role these Asian-based developers have played in establishing an emerging urban public domain in some dense Asian cities.

Design and eco-technoeconomic analysis of a natural gas cogeneration energy management center (EMC) with short-term thermal storage

This work proposes a non-islanded cogeneration energy management center (EMC) that can be used to displace grid-level natural gas turbine systems and natural gas combustion systems for heat. The design of the proposed EMC included a weighted multi-objective optimization aimed at minimizing: i) natural gas consumption; ii) capital costs; iii) utility costs; and iv) unmet thermal demand. The decision variables consisted of the existence and capacity of the equipment comprising the EMC, including: i) a natural gas boiler; ii) an internal combustion engine that generates heat and electricity; and iii) a hot water thermal storage system. Four resulting candidates EMC designs were then compared with the status-quo (SQ) in an eco-technoeconomic analysis; The SQ draws electricity from the grid and heating for dwellings come from natural gas boilers. Emissions at grid level change which alternative is favored. The findings showed that, for a system that serves 4–5 dense urban city blocks over a 20-year lifetime, the SQ system had cumulative levelized costs of 9.6 million USD for the final consumer, while the levelized costs of the EMC designs ranged from 12.9 to 15.1 million USD. In terms of emissions, the SQ emitted 959 tonnes of CO2eq per year, while the EMC system produced around 500 tonnes of CO2eq per year depending on the year, yielding a CCA varying between 364 and 653 USD/tonneCO2eq

EVOLVING RESEARCH METHOD IN THREE-DIMENSIONAL AND VOLUMETRIC URBAN MORPHOLOGY OF A HIGHLY DENSE CITY: ASSESSING PUBLIC AND QUASI-PUBLIC SPACE TYPOLOGIES

An appropriate urban density is a vital part of a sustainable urban fabric. However, when it comes to measuring the built urban fabric and how people walk through it and use, a difficulty has been observed in defining applicable measurement tools. With the intention of identifying the variables that will allow the best characterization of this fabric and movement, a multi-variable analysis methodology from the field of artificial intelligence (AI) is proposed. The main objective of this paper is to prove the capacity of AI as an evolving research method in urban morphology and specifically to evaluate the capacity of such a methodology to measure the way in which people travel through defined multi-levels of typologies of public urban space. The research uses the case of Hong Kong as a dense city that is three-dimensionally activated in terms of its public realm, not just at street level, but also via below ground subways and upper-level walkways, public and quasi-public spaces. This includes the three-dimensional volumetric assessment of public and quasi-public space typologies within a highly dense city. For the purpose of the study, a characterization and term definition of these spaces has been further developed: “Junctions”, “Landmarks”, “Intersections”, “Districts”, “Passages” and “Lobbies” (both outdoor and indoor) based on Lynch’s 5 main key elements (District, landmark, path, edges, node). The results obtained using AI prove to be more robust and rational than those based on a more limited range of tools, evidencing that using AI can offer operational opportunities for better understanding of morphological and typological evolution within the vertical and volumetric built urban fabric.

Spatial inequity index for essential facility access at building-level in highly dense urban areas

Equity and inclusion continue to pose significant challenges for many cities. Disparities in access to resources and facilities among the residents of these areas are often influenced by factors such as geographical location and income level, among others. Therefore, creating a quantitative basis to detect spatial and socio-economic inequities in residents' access to vital infrastructures is crucial for advancing smart cities. This paper introduces a novel measure of Spatial Inequity that is based on 1) computing building-level scores for each building in terms of access to facilities, and 2) comparing the distribution of the scores of these facilities using the Gini coefficient. The proposed building-level scores will enable the identification of GIS hotspots at a high resolution. Then, the Gini-based measure will facilitate a comparison of the distribution of the scores, and determine if they are evenly distributed and equitably accessible. The Gini coefficient was highest (0.89) for waste management and elderly care, and lowest (0.56) for hospitals, reflecting varying levels of inequality. This study applies this Spatial Ineqity methodological framework to Hong Kong, a representative of Highly Dense Cities. The framework benchmarks urban infrastructure, identifies hotspots, and selects interventions for equitable urban development.

Comparative Study of Aerosol Optical Properties along a Megacity

Interest in the study and characterization of aerosols has been growing given its multiple connections with air quality and climate. However, the limited ground-based stations for measurements in many countries are not enough to completely study a big city or a region. Low-cost technology arises as a viable alternative to improve the spatial resolution of measurements. This study aims to demonstrate that the properties of aerosols may change within a megacity and that is advisable to segment measurements according to their characteristics. We measured the optical properties of aerosols in the outskirts of Buenos Aires and compared the data obtained with AERONET data from the city center. This is the first study of its kind in the region. The comparison of concentration, sizes, and types of aerosols shows differences between the sites regardless of the background levels that they share regionally. While the city center has a strong influence from traffic and sea particles and levels of pollution typical of a dense city, the outskirts present several aerosol sources and characteristics of a semi-rural site with a moderate influence of anthropogenic sources.

Impact of Settlement Size and Regional Density on the Frequency of Different Holiday Types

Despite its contribution to climate change, holiday travel has received less attention in research than daily travel. Research has revealed that individuals residing in dense and large settlements tend to travel more frequently and over longer distances. Whether this is attributable to compensation for shortcomings of dense cities or a reflection of lifestyle is still inconclusive, yet important to uncover for formulating mitigation strategies for the environmental impact. To advance this discussion, we analyze the 2019 Norwegian holiday travel survey to determine to what extent settlement size and regional density in Norway are associated with different holiday types that reflect different lifestyles and motivations. Using negative binomial and logistic regression while controlling for socioeconomic factors, we find that (1) it is not settlement size that influences the number of holiday trips, but whether a settlement lies in a dense county; (2) making nature getaways in Scandinavia and intercontinental trips are both positively associated with county density; (3) making city trips does not show a consistent link with spatial characteristics; (4) Mediterranean seaside holidays are typical for all Norwegians, no matter the place of residence. Our results indicate compensatory motivation behind nature getaways. However, dense everyday surroundings are not detrimental to visiting other densely populated areas on city vacations. The increased likelihood of intercontinental trips among people in dense areas may be explained by lifestyle and cosmopolitan attitudes rather than being a result of compensation.

Novel approach to roof rainwater harvesting and aquifer recharge in an urban environment: Dry and wet infiltration wells comparison

In urban environments there is a severe reduction of infiltration and groundwater recharge due to the existence of large impervious areas. During rain events, large volumes of water that could have recharged groundwater and surface water bodies are diverted into the municipal drainage system and lost from the freshwater storage. Moreover, extreme rain events impose high peak flows and large runoff volumes, which increase the risk of urban floods. Recent studies have suggested the use of rainwater harvesting for groundwater recharge, as a plausible solution for these challenges in dense urban environments. While the benefits of this approach are well understood, research on its practical, engineering, and hydrological aspects is relatively limited. The objective of the present study was to examine the use of infiltration wells for groundwater recharge with harvested rainwater collected from building rooftops under Mediterranean climate conditions. Two types of wells with similar hydraulic and technical properties were examined: a well that reaches the groundwater (wet well); and a well that discharges the harvested water into the unsaturated zone (dry well). Infiltration capacities of the wells were compared in controlled experiments conducted during summer months, and in operational recharge of harvested rainwater, during winter. Both dry and wet wells were found to be suitable for purposes of groundwater recharge with rooftop-harvested rainwater. Infiltration capacity of the wet well was about seven times greater than the infiltration capacity of the dry well. While the infiltration capacity of the wet well was constant throughout the entire length of the study (∼10 m3/h/m), the dry well infiltration capacity improved during winter (from 0.5 m3/h/m to 1.5 m3/h/m), a result of development of the dry well with time. Considering Tel-Aviv, Israel, as a case study for a dense modern city in a Mediterranean climate, it is demonstrated herein that the use of infiltration wells may reduce urban drainage by ∼40 %.