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1. Urban forms across continents: A data-driven comparison of Lausanne and Philadelphia

   https://doi.org/10.1016/j.trip.2025.101823  

   Carmès, Arthur; Catteau, Léo; Sonta, Andrew; Tavakoli, Arash (March 2026, Transportation Research Interdisciplinary Perspectives)

   Understanding urban form is crucial for sustainable urban and transportation planning, and for enhancing quality of life. This study presents a data-driven framework to systematically identify and compare urban forms across geographically and culturally distinct cities. Using open-source geospatial data from OpenStreetMap, we extracted multidimensional features related to network structure, multimodality, green spaces, and points of interest for the cities of Lausanne, Switzerland, and Philadelphia, USA. A grid-based approach was used to divide each city into Basic Spatial Units (BSU), and Gaussian Mixture Models (GMM) were applied to cluster BSUs based on their urban characteristics. The results reveal coherent and interpretable urban forms within each city, with some cluster types emerging across both cities despite their differences in scale, density, and cultural context. Comparative analysis showed that adapting the grid size to each city’s forms improves the detection of shared typologies. Simplified clustering based solely on network degree centrality further demonstrated that meaningful structural patterns can be captured even with minimal feature sets. Our findings suggest the presence of functionally convergent urban forms across continents and highlight the importance of spatial scale in cross-city comparisons. The framework offers a scalable and transferable approach for urban analysis and transportation planning providing valuable insights for planners and policymakers aiming to enhance various aspects of cities including walkability, accessibility, and well-being. Limitations related to data completeness and feature selection are discussed, and directions for future work — including the integration of additional data sources and human-centered validation — are proposed. 

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2. Where Are the City Trees? Monitoring Urban Trees across the U.S. Using Generative AI

   https://doi.org/10.1145/3762636  

   Firoze, Adnan; Uppala, Akshaj; Darling, Lindsay; Yeh, Raymond A; Benes, Bedrich; Hardiman, Brady; Fei, Songlin; Aliaga, Daniel (April 2026, Communications of the ACM)

   Finding where the trees are in a city and monitoring any changes are essential for sustainable urban management. Historically, urban forests are mainly inventoried via manual processes often limited to public lands. Leveraging advances in computing, we present a novel generative artificial intelligence (AI) method along with a first-ever national-scale dataset, to automatically localize trees in cities across the nation using satellite imagery. Our monitoring approach is fully automated and can be completed for 330 U.S. cities within less than a day of computing, enabling actionable knowledge of changes in urban trees and supporting sustainable development decisions. We successfully localized and counted over 278 million trees, achieving an average tree count accuracy of 92.5% and spatial accuracy of 1.5m for 2024–2025. Our computational approach allows for novel nationwide analysis to be performed. For example, we can localize approximately 117 million trees on private lands and 161 million on public lands. Further, we show and quantify that urban tree distribution exhibits strong spatial disparity, with low-income communities having substantially fewer trees and less canopy cover than others. In addition, we compare tree count and layouts before and after multiple major events (e.g., major fires and destructive weather phenomena). Overall, our approach enhances computational urban planning, including weather and extreme event forecasting, for the development of sustainable cities. 

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3. Economies of Inequality? Polycentric Metropolitan Governance and Strategic Sustainability Choices

   https://doi.org/10.1177/10780874241252755  

   Deslatte, Aaron; Helmke-Long, Laura; Stokan, Eric; Chung, Juwon (May 2024, Urban Affairs Review)

   This article examines the relationship between the political fragmentation of cities in metropolitan regions, the distribution of social vulnerability, and the city-level economic and social sustainability strategies they adopt. Strategies emerge from prevailing community norms, and polycentric governance arrangements can support conditions in which both economic and social sustainability strategies emerge as compliments, contrary to the concern that fragmentation spurs zero-sum competition. Combining surveys of U.S. cities with social vulnerability data and text analysis of planning documents, we find that greater fragmentation has a negative impact on the sustainable development strategies cities adopt. However, growth and sustainable development strategies tend to develop alongside social sustainability efforts to address human needs. We conclude that development strategies emerge in polycentric systems in relation to the degree of fragmentation which exists, and that subsequent work should continue to focus on identifying these entropic thresholds in order to effectively address lingering inequities. 

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4. Zooming in on Arctic urban nature: green and blue space in Nadym, Siberia

   https://doi.org/10.1088/1748-9326/ac0fa3  

   Fedorov, R; Kuklina, V; Sizov, O; Soromotin, A; Prihodko, N; Pechkin, A; Krasnenko, A; Lobanov, A; Esau, I (July 2021, Environmental Research Letters)

   Abstract Urban landscape combines built-up areas with strongly altered natural (green and blue) and other open spaces. Voluminous literature examines urban socio-environmental interactions in tropical and temperate cities, whereas high-latitude cities are rarely considered. Here, we create a historical perspective on urban green (vegetation) and blue (water) spaces in a sub-Arctic city of Nadym in Russia. Our study explores a novel way to combine quantitative information from satellite imagery and biometric studies with qualitative information from interviews with stakeholders and residents. Such a joint analysis helps to understand dynamics of the urban green and blue space as well as its value for society. Furthermore, we propose objective indicators reflecting societal values of spaces in connection with recreational and ecological services. By contrast to temperate city studies, we found that green space is less used in summer, but still highly valued, deep lakes are used and valued more than warmer shallow lakes, and winter white space do not shrink but enhance the urban public space. Satellite images reveal inevitable loss of green space to urban construction and its remediation by artificial plantings (almost by 30% at present), whereas less valued blue space decreased almost three-fold. Interviews reveal that shallow lakes have reduced recreational values due to ice bottom and algae bloom. High values are attributed to deep artificial lakes, which are more than ten times deeper than natural lakes and do not freeze throughout in winter. Our biometric studies show that trees in urban environment are significantly taller than in the corresponding undisturbed areas. Since majority of the Arctic cities are built using very similar planning ideas and technologies, our findings shall help objective appreciation of green and blue spaces in other settlements. 

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5. Green spaces as an indicator of urban sustainability in the Arctic cities: Case of Nadym

   https://doi.org/https://doi.org/10.1016/j.polar.2021.100672  

   Kuklina, Vera; Sizov, Oleg; Fedorov, Roman (March 2021, Polar science)

   null (Ed.)

   Green spaces have recently received wide acknowledgement for urban sustainability benefits and are mentioned in the Sustainable Development Goals SDGs Target 11.7. The article aims to address the knowledge gap on indicators used for assessment of green spaces for urban sustainability in the Arctic using an example of Nadym, Russia which is illustrative of compact cities built during the Soviet time using a system of microrayons. Different indicators implemented by international organizations for assessment of green spaces are compared with indicators used in Russia. Utilizing very high-resolution WorldView-3 satellite image and open source data, the quantity and quality of green spaces are estimated with high accuracy. In addition to traditionally used indicators of share of green space per capita, share of public spaces for common use within walking distance to assess availability and accessibility of green spaces, the paper suggests importance of taking into account governance, distribution, and composition using analysis of historic legacies, municipal budget allocation for green space maintenance, and Normalized Difference Vegetation Index values. Such detailed view can enrich discussions about green spaces as sources for resilience both at the local and global levels, in comparison with other cities and across countries. 

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