Dense City Research Articles

Everything Stays the Same while Everything Changes

Everything Stays the Same while Everything Changes

Sky Gardens, Public Spaces and Urban Sustainability in Dense Cities: Shenzhen, Hong Kong and Singapore

This paper studies the spatial characteristics of sky gardens as public spaces to explore their potential to support urban sustainability in dense cities. This research understands public spaces as spaces that are open and available in different levels of access and use. The research focuses on 982 sky gardens in Shenzhen, Hong Kong, and Singapore. It adopts a mixed methodology, including site visits and observations, statistic measurements (based on SPSS software), and Grey Relation Analysis (GRA) methods. The research follows three steps: first, it studies the urban context, including urban density, land uses, and policy regulations regarding sky gardens and sustainability. Second, it examines sky gardens’ spatial characteristics in terms of form (morphology, typology, size, affordances, configuration), openness quality (accessibility, ownership, permeability), and geometry (open space ratio, height of space-to-building, void-to-solid ratio, shape index). Third, the research compares the findings in three case cities and discusses their potential to support urban sustainability. The results suggest that despite the limitations of sky gardens, they may play, to different degrees, fundamental roles as open public spaces in high-density urban environments supporting cities’ sustainability. High-density environments offer more opportunities for the sustainable development of sky gardens, which creates a new spatial paradigm for compact vertical greenery in high-density cities.

Estimating wider economic impacts of transport infrastructure Investment: Evidence from accessibility disparity in Hong Kong

Much recent work on transport and the economy has focused on ‘Wider Economic Impacts’ (WEIs) of infrastructure investment, the impacts other than time savings benefiting those actually using the transport network. Differential effects of transportation infrastructure by mode such as urban rail and road are relatively well known. However, impacts of other mode such as walking are scarce. This paper estimates wider economic impacts related to productivity from full rail, road and walking transport networks in Hong Kong in 2016. To the best of our knowledge, this is the first paper that makes use of complex network science indicators with spatial cognition-weighted accessibility combining full urban rail network, road network, and pedestrian network in capturing wider economic impacts. We use an instrumental variable approach to identify the causal effect of transport network centralities on productivity measured by gross value added. Our identification strategy largely relies on the exogenous variations from historical planned and existing transport networks. A first specification confirms the significance of urban rail and road. Specification with pedestrian network shows that pedestrian and rail networks can statistically significantly increase productivity in Hong Kong while roads play a less significant but still meaningful role. Our findings are robust to a variety of sensitivity tests such as using night-time light intensity and residential wage as alternative measures for productivity. The research suggests a key planning policy implication: place-based policies in a dense city require improvement in pedestrian and rail network structure that impacts local and global transport accessibility.

15-, 10- or 5-minute city? A focus on accessibility to services in Turin, Italy

The concept of the 15-minute city is receiving increasing attention, both in planning practices and in the academic literature, especially now that the pandemic has made evident the need for a minimum set of proximity-based services accessible by active travel. Most issues of this concept can be traced back to more or less past planning ideas such as the garden city, the neighbourhood unit, the superblock etc.; however, further studies are needed, as many theoretical and methodological questions for its implementation remain unresolved. The paper presents a methodology to operationalise the concept of the 15-minute city, in order to show which parts of the city and what percentage of its population can access a location of a given service on foot within three time thresholds (5, 10 and 15 minutes). The methodology is tested on the Italian city of Turin. The results show that, at least in dense European cities such as the case study, the 15-minute threshold cannot always be assumed as the necessarily most appropriate target, since many services can already be reached by foot within this time, or even less, by the majority of the population. Moreover, the levels of accessibility to services are significantly determined by the number and spatial distribution of the locations of these services. Finally, a recovery of the operational research on accessibility measures and indicators that was developed in the field of regional sciences in the second half of the last century and in the last twenty years is recommended to complexify the operationalisation of the 15-minute city concept.

Analyzing spatial inequalities in use and experience of urban green spaces

As cities become more densely populated, urban green spaces (UGS) are increasingly important due to the environmental and social benefits they provide. Cities are confronted with the challenge of equitable supply of high-quality urban green that meets the demand of residents. This is particularly relevant in lower-income neighborhoods, which tend to suffer from the lowest supply of (high quality) UGS. In this paper, we perform spatial analysis on the responses of an online user survey to explore how UGS frequency of use, choice, and satisfaction differ by use pattern and place of residence in the Brussels Capital Region. Additionally, we identify the “push-pull” factors of individual UGS by identifying the desirable (pull) and undesirable (push) qualities that may attract or repel the use of a UGS. We find that use pattern is related to choice and experience of UGS. Compared to people who use UGS for social purposes, those who use UGS for nature-oriented reasons more often choose to visit UGS that are substantially farther from their home but are more often satisfied with the UGS they use. Our findings also show that respondents living in areas with higher proportions of disadvantaged groups tend to travel substantially farther to reach their UGS and are more often dissatisfied with the UGS they visit. Finally, our push-pull analysis indicates that characteristics that are important to nature-oriented users, such as quietness and calmness, are often more negatively experienced in dense city center UGS. Our research thus demonstrates the need to bring more green, particularly green that elicits a feeling of “naturalness”, to areas of the city where low green space quality and quantity overlap with areas inhabited by vulnerable populations.

Identifying Hospital Deserts in Texas Before and During the COVID-19 Outbreak.

In this study, we proposed a GIS-based approach to analyzing hospital visitors from January to June 2019 and January to June 2020 with the goal of revealing significant changes in the visitor demographics. The target dates were chosen to observe the effect of the first wave of COVID-19 on the visitor count in hospitals. The results indicated that American Indian and Pacific Islander groups were the only ones that sometimes showed no shift in visitor levels between the studied years. For 19 of the 28 hospitals in Austin, TX, the average distance traveled to those hospitals from home increased in 2020 compared with 2019. A hospital desert index was devised to identify the areas in which the demand for hospitals is greater than the current hospital supply. The hospital desert index considers the travel time, location, bed supply, and population. The cities located along the outskirts of metropolitan regions and rural towns showed more hospital deserts than dense city centers.

The challenges of implementing green factors in urban greening schemes in Indonesia

Recently, new planning tools have emerged to support urban landscape planners in achieving sustainability through optimizing the urban greening scheme. Some cities have approved the green factor tool to increase the quantity and quality of urban green spaces. This greening scheme is considered suitable for a relatively dense city where challenging to provide adequate urban green areas. This short communication challenges the usefulness of the green factor tool and how it relates to the existing urban green space planning procedures through a qualitative case study in Jakarta, Indonesia. The result shows that while the green factor tool performs well, improvements could be made primarily in convincing stakeholders regarding the new paradigm in calculating green areas in relatively dense urban areas. Furthermore, trials in actual cases need to be carried out to examine the formula’s effectiveness. Regarding the usefulness of this tool, we conclude that while increasing the number of green areas, improving its quality is more necessary to build resilient infrastructures.

Abstract 1022: Disparities in accessibility to oncology care centers in France

Abstract Background: Cancer caused nearly 10 million deaths in 2020. While most of the ongoing research focuses on finding new treatments, accessibility to oncology care receives less attention. However, access to health services plays a key role in cancer survival. Spatial accessibility methods have been successfully applied to measure accessibility to primary care. Yet, little research to date focused on oncology care specifically. Methods: We focused on all care centers with medicine, surgery, or obstetric activity in metropolitan France. We propose a clustering algorithm to automatically label the hospitals in terms of oncology specialization. Then, we computed an accessibility score to these hospitals for every municipality in metropolitan France. Finally, we proposed an optimization algorithm to increase the oncology accessibility by identifying centers which should increase their capacity. Results: We labelled 1,662 care centers into 8 clusters. Half of them were eligible for oncology care and 118 centers were identified as experts. We computed the oncology accessibility score for 34,877 municipalities in metropolitan France. Half of the population lived in the top 20% accessibility areas, and 6.3% in the bottom 20% zones. Accessibility was higher near dense cities, where the experts care centers were located. By combining the care centers clusters and the accessibility distributions, our optimization algorithm could identify hospitals to grow, to reduce accessibility disparities. Conclusion: Our method made it possible to quantify oncology care accessibility across all metropolitan France, as well as to make suggestions on where to increase hospital capacity to improve accessibility, especially in more populated suburban areas. Our approach was deliberately non-specific to cancer type nor to the kind of stays, but it could be adapted to more specific scenarios. We packaged our method into a web application allowing the users to run the algorithms with various parameters and visualize the results. Citation Format: Eric Daoud, Anne-Sophie Hamy, Elise Dumas, Lidia Delrieu, Beatriz Grandal, Christine Le Bihan-Benjamin, Sophie Houzard, Philippe-Jean Bousquet, Judicael Hotton, Aude-Marie Savoye, Christelle Jouannaud, Chloé-Agathe Azencott, Marc Lelarge, Reyal Fabien. Disparities in accessibility to oncology care centers in France [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1022.

Denied delights of daylight in density: Optimizing building codes to achieve maximum daylight in apartments of Dhaka, Bangladesh

Daylight-inclusive building codes are difficult to establish for rapidly developing dense urban centers in the global south. Obstruction Angle (OA) has long been used as a precursor in daylight-inclusive building codes. However, such codes are more suitable for higher latitude cities with low-rise developments but less effective in low latitude dense cities such as Dhaka. Existing research established Unobstructed Vision Area (UVA) as a critical daylight precursor for dense urban developments. This study further established Canyon Wall Porosity (CWP) as another critical daylight precursor and detailed a CWP calculation method. Via OA, UVA, and CWP, this study examined existing Dhaka building codes against optimal values for setbacks, building height limit, Floor Area Ratio (FAR) and Maximum Ground Coverage (MGC). The findings revealed: (a) 63° OA is critical for Dhaka, and it should be used to set setbacks distances and building height limits (b) front setbacks could be narrower as streets assist in sustaining 63° OA, but rear-setbacks should be significantly wider (c) MGC should be lower to achieve high CWP for adequate daylight. These findings, especially the introduction of CWP for daylight inclusivity, could be a catalyst for solar legislation in other mega-urban centers on similar latitudes.

Analysis of Mn accumulation onto plants in urban areas

The biggest problem in dense cities is air pollution and the damage to the environment caused by vehicles. Roadside landscape plants are exposed to pollutants, especially in small urban centers, which are caused by congested traffic. According to the type of landscape plants, being a good biomonitor varies according to their adsorbing capacity of pollutants. Fe and Mn are the leading pollutants originating from emissions. They are selected within the study and have various negative effects on plants in high concentrations. This study aimed to determine the Mn concentration changes according to organ and washing status and location of selected commonly used 14 landscape species in parks. The heavy metal holding capacity of 14 species used was compared the Mn concentration changed significantly depending on the factors evaluated to adsorb them. Chamaecyparis lawsoniana (A. Murr.) Parl. and Photinia serrulata Lindl. Where the highest values are obtained, they can reduce Mn pollution. Schinus molle L. is a suitable type that can monitor and mitigate the Mn concentration in the air.

Towards Ecological Management and Sustainable Urban Planning in Seoul, South Korea: Mapping Wild Pollinator Habitat Preferences and Corridors Using Citizen Science Data.

Simple SummaryUrban landscapes, though a primary contributor to habitat fragmentation, have the potential to facilitate habitat connectivity for native pollinator species, especially with strategic green space planning. Citizen science data have been proven to be useful to address conservation issues in urban areas, especially where knowledge is lacking about species richness and habitat preferences. In this study, we used data collected by a citizen science program between 2016 and 2018 to determine which families of pollinators were the most frequently observed in Seoul, with which habitats pollinators had the highest affinities, and what parts of the city facilitated habitat connectivity. We found that the most suitable habitats for multiple families were located in public parks, university campuses, and Cultural Heritage sites. These results are directly applicable in order to better understand urban planning stakes for pollinators and wildlife in general and provide avenues for improvement to recreate functional greenways in a dense city like Seoul.The preservation and restoration of habitats and ecological connectivity inside cities is crucial to ensure wildlife can find suitable areas to forage, rest and reproduce, as well as to disperse, thereby allowing metapopulation functioning. In this study, we used data collected by a citizen science program between 2016 and 2018 to determine which families of pollinators were the most frequently observed in Seoul and with which habitats pollinators had the highest affinities. Using species distribution modeling and landscape graph approaches, we located the main habitats and corridors to reinforce connectivity for six pollinator families. Finally, we identified habitats and corridors where conservation actions should be prioritized. In total, 178 species belonging to 128 genera and 60 families were observed. Hymenopterans were the most recorded, followed by dipterans and lepidopterans. The most suitable habitats for pollinators were constituted of public parks, university campuses, and Cultural Heritage sites. In a dense city like Seoul, most of the conservation corridors are located in built-up areas. Innovative urban planning and architecture are therefore required as well as the setting-up of ecological management practices to lead to a more sustainable urbanism for pollinators and wildlife in general.

Renewal of waterways in a dense city creates value for residents

Water sensitive practices can improve water quality and city livability, but the extent to which these practices improve the welfare of residents is not well researched. We contribute to knowledge in this area using Singapore's Active, Beautiful, Clean Waters (ABC Waters) Program as a case study. The program includes the renovation and integration of drains, canals, and reservoirs with the surrounding environment. To investigate impacts, we analyse real estate transactions within 2000 m of 13 canals that were renovated between 2008 and 2016 as part of the ABC Waters program using both a difference-in-differences hedonic price model and a difference-in-differences exact matching model. To test the robustness of the result, we implement a placebo test by shifting the restoration project dates. We find the value of residential flats within 500 m of renovation sites increase by 1.6% (95% CI 1.0–2.2%) after renovation projects. The empirical strategy and the placebo test results support a causal interpretation of the effect of canal renovation projects on flat prices. The uplift in value for flats within 500 m of canal upgrading projects is estimated to be between S$336 and S$504 million. This exceeds the combined costs of all ABC Waters projects and provides evidence that the benefits of urban waterway renewal projects are greater than the costs.

Trip-pair based clustering model for urban mobility of bus passengers in Macao

ABSTRACT Public transit is a major mode of urban mobility in Macao, a compact and populous city in China. Public transit ridership is related to round-the-clock shift-based work arrangements in the gaming industry. Smartcards that are used in transit fare collection are a vital data source for understanding the travel patterns and characteristics of transit passengers. However, transactional information from single data sources is fragmented, hindering the extraction of mobility patterns. We proposed a trip-pair-based clustering model that extracts the within-day mobility patterns of bus riders. DBSCAN is employed to filter scattered trips and hierarchical agglomerative clustering to identify clusters. Using a six-month smartcard dataset from Macao, categories of bus passengers were identified. Travel patterns exist with irregular, one-way, and round-trip passengers, and shift workers. The unique shift-based work-life and mixed travel modes in Macao can serve as an example of dense and compact city travel for smart cities.

Application of Multi-Channel Convolutional Neural Network to Improve DEM Data in Urban Cities

A digital elevation model (DEM) represents the topographic surface of the Earth and is an indispensable source of data in many applications, such as flood modeling, infrastructure design and land management. DEM data at high spatial resolution and high accuracy of elevation data are not only costly and time-consuming to acquire but also often confidential. In this paper, we explore a cost-effective approach to derive good quality DEM data by applying a multi-channel convolutional neural network (CNN) to enhance free resources of available DEM data. Shuttle Radar Topography Mission (SRTM) data, multi-spectral imaging Sentinel-2, as well as Google satellite imagery were used as inputs to the CNN model. The CNN model was first trained using high-quality reference DEM data in a dense urban city—Nice, France—then validated on another site in Nice and finally tested in the Orchard Road area (Singapore), which is also an equally dense urban area in Singapore. The CNN model not only shows an impressive reduction in the root mean square error (RMSE) of 50% at validation site in Nice and 30% at the test site in Singapore, but also results in much clearer profiles of the land surface than input SRTM data. A comparison between CNN performance and that of an earlier conducted study using artificial neural networks (ANN) was conducted as well. The comparison within this limited study shows that CNN yields a more accurate DEM.

Developing a data-fusing method for mapping fine-scale urban three-dimensional building structure

Understanding urban morphology is essential for various urban management studies and local environmental issues and guiding sustainable city development. Existing studies mainly focus on analyzing urban morphology from the horizontal aspect, while the urban vertical structure has rarely been discussed due to the scarcity of reliable and fine-scale urban three-dimensional (3-D) building data. This study develops an effective data-fusing methodology to estimate the heights of individual buildings at a city scale. We examined a machine-learning regression model by collecting public materials, including multi-source remote sensing-(RS)-based products, building-derived features, and relevant data to verify its performance in building height estimation. By applying the model in Shenzhen City, a dense city in the Guangdong-Hong Kong-Macao Greater Bay Area, results demonstrated that integrating rich multi-source explanatory variables could achieve high-accuracy building height retrieval. Using multiple building morphological metrics derived by building height data as proxy measures, the urban 3-D form patterns were further analyzed to understand current heterogeneous urban morphological structures. The proposed methodology can be conveniently applied to worldwide cities for urban 3-D morphology retrieval. Also, the available building height information is useful for planners to design morphological control for cities and thus contributes to sustainable and smart city development.

Urban performance based on biometeorology index in high-density, hot, and humid cities

• The correlation between high density and urban performance based on biometeorology index for eight metropolitan cities in Indonesia is introduced. • The need to re-evaluate spatial planning in Indonesia, especially cities with high BCR is the urgency to achieve a preferred urban biometeorology. • Reducing BCR especially in dense area to promote 30% open space by increase the value of FAR. • The results show potential improving urban biometeorology by promote FAR to increase urban ventilation. This article aims to discuss urban performance based on the biometeorology of eight dense cities in Indonesia (i.e., Jakarta, Bandung, Medan, Padang, Pontianak, Banjarmasin, Makassar, and Denpasar). The interconnection between urban morphology and human biometeorology provides an understanding of meteorological vulnerability and thermo–physiological aspects, which is expressed as the physiologically equivalent temperature (PET). The hourly meteorological data from eight cities’ weather stations was collected from 2009 to 2019. The building density is later defined as the building coverage ratio (BCR) and is divided by a low BCR, which is less than 70%, and a high BCR, which is more than 70%. The BCR is then correlated with the meteorology variables, Ta max, RH, and v, to calculate its impact on the PET. The increase of Ta max in cities, both for low BCRs ( r = 0.76) and high BCRs ( r = 0.54), is found to have a significant correlation with an increase in PET. Meanwhile, increasing the value of v for both low BCRs ( r = -0.67) and high BCRs ( r = -0.65) decreases PET . However, modifying the value of the PET for cities with a high BCR is more complicated. The microclimate within the building layout must be manipulated to increase the value of v . A humid condition for a high BCR is beneficial to reduce the PET.

Open Space Implications in Urban Development: Reflections in Recent Urban Planning Practices in Nepal

Open space has various implications in urban development planning and has been integrated in recent urban planning approaches and practices in Nepal. The open spaces are not only important for (re)shaping the urban form but are also important for enhancing urban social life and disaster risk management, particularly for dense cities. As most of the cities in Nepal have been growing haphazardly, the cities lack sufficient open space. However, the value of open space in dense cities like Kathmandu has been recognized more after the Gorkha Earthquake 2015 as the open spaces were extensively used for risk relief, treatment, recovery, and rehabilitation during and after the earthquake. With this background, this paper presents the major planning initiatives in Nepal and discusses how recent urban plans have provisioned and initiated open spaces development by reviewing concurrent urban planning practices, particularly reviewing Periodic Plans, Integrated Urban Development Plan, Smart City Plan, and Land Development Plan. The development of open areas has not been given much attention in the earlier urban planning practice but recent urban development planning has emphasized with a special focus which is very important for sustainable and safer city development and is expected to address the current bulging urban issues of spatiality and sociability. Therefore, it is very important for integrating open space implications in city planning and such open space should be conceptualized according to the city’s geography, landscape as well as socio-cultural contexts.

EPSILON: An Efficient Planning System for Automated Vehicles in Highly Interactive Environments

In this article, we present an efficient planning system for automated vehicles in highly interactive environments (EPSILON). EPSILON is an efficient interaction-aware planning system for automated driving, and is extensively validated in both simulation and real-world dense city traffic. It follows a hierarchical structure with an interactive behavior planning layer and an optimization-based motion planning layer. The behavior planning is formulated from a partially observable Markov decision process (POMDP), but is much more efficient than naively applying a POMDP to the decision-making problem. The key to efficiency is guided branching in both the action space and observation space, which decomposes the original problem into a limited number of closed-loop policy evaluations. Moreover, we introduce a new driver model with a safety mechanism to overcome the risk induced by the potential imperfectness of prior knowledge. For motion planning, we employ a spatio-temporal semantic corridor (SSC) to model the constraints posed by complex driving environments in a unified way. Based on the SSC, a safe and smooth trajectory is optimized, complying with the decision provided by the behavior planner. We validate our planning system in both simulations and real-world dense traffic, and the experimental results show that our EPSILON achieves human-like driving behaviors in highly interactive traffic flow smoothly and safely without being overconservative compared to the existing planning methods.

Small Green Spaces in Dense Cities: An Exploratory Study of Perception and Use in Florence, Italy

This study investigates human perception and use of Small Green Spaces (SGS) in a dense Western city (Florence, Italy). While there is some work on social dynamics in large urban parks, empirical studies of SGS are fewer. The research adopts an exploratory approach with a mixed methods strategy (observation sessions, 50 in-depth interviews, and 430 questionnaires). The analysis is framed within a tripartite model of interaction between people and space as spontaneous appropriation of space through the body, senses, and mind. The analysis of use patterns, practices, and conflicts in SGS illustrates how continuous use and proximity make SGS persistent scenarios of users’ daily life, differently from large city parks. Sociality and restorative opportunities afforded by natural features define users’ experiences and SGS appreciation across genders and age groups. The discussion illustrates how the theoretical constructs of functional indetermination and non-normativity explain users’ perception of SGS as open-ended settings, spared from the extensive compression of publicness and commodification of other public spaces in contemporary cities. Implications of the study outcomes are discussed in relation to social cohesion in open public spaces and with the declining sense of urbanity in large cities. Some indications on design, planning, and management of SGS are also suggested.

Expanding urban green space with superblocks

The Barcelona superblock is an urban neighbourhood transformation strategy, with which car-based traffic is redirected away from streets that are inside a 3 × 3 urban block configuration. This urban design concept promises opportunities for alternative street use such as the transformation of street space into urban green space. The potential to foster urban green space due to superblock design is however unclear, particularly outside of the original Barcelonan context. Concerning urban densification, fostering urban green space is particularly relevant to achieving dense and green cities. In this study, potential superblocks are identified in all major Swiss cities and the current urban green space is quantified. This analysis reveals distinct differences of superblock opportunities and urban green space between different cities and allows pinpointing opportunities for expanding urban green space. Considering the nine largest Swiss cities, between 3% and 18% of the current street network was simulated to be potentially suitable for superblock implementation to transform the streetscape and increase urban green space. The variation of current urban green space coverage across all potential individual superblock sites that have high urban density ranges considerably from a few percentages to above 30%. The presented results allow the exploration of urban green space opportunities at street and block-level arising from superblocks in Switzerland. For example, when considering a citywide superblock implementation scenario, the potential street area is relatively high for Basel whilst at the same time showing relatively low current availability of urban green space. For creating detailed design or transformation strategies based on the explored superblock sites, more integrated analysis to evaluate potential benefits as well as disservices of such urban transformation is required.