Search Results (87)

Forgotten spaces, often referred to as lost spaces or non-places, represent a crucial challenge in contemporary urbanism and sustainable urban development. They are underdeveloped and undesirable urban areas that are in urgent need of rethinking, replanning, and redesign. They are mostly undefined, lacking measurable boundaries and communication routes. These natural areas are usually neglected and underutilized, which leads to their insufficient exploration from an urban-ecology perspective. Due to the impacts of climate change, it is necessary to reintegrate these lost places into urban planning. In organized non-spaces, it is crucial to rediscover their function and make these areas accessible or released for use. Wetlands, rich in biodiversity in urban areas and subject to seasonal changes, are threatened by human activity, and their protection is essential for the sustainable development of cities and urbanism today. Cities are interwoven with such non-places, which exhibit various characteristics within the urbans system. In conclusion, unrecognized urban spaces and lost wetlands represent an untapped potential for sustainable urban ecosystem development. This shifts the perception of urban voids from traditional urbanization towards their new potential as spaces for green development within the framework of sustainable contemporary cities. Full article

This systematic review examines and critically classifies the strategies applied to abandoned urban voids through the analysis of peer-reviewed scientific and technical literature, addressing the lack of integrative studies on the topic. A systematic search was conducted in the SCOPUS database for articles published between 2000 and 2025, following the PRISMA 2020 guidelines. Sixteen studies that met the inclusion criteria were analyzed using the digital tool Parsifal. The results reveal that adaptive reuse and architectural regeneration are the predominant strategies for transforming abandoned urban voids, aimed at converting underutilized or abandoned spaces into functional and socially integrated urban assets. In contrast, approaches such as rehabilitation and environmental remediation appear less frequently but highlight the importance of ecological and preparatory interventions. This review also identifies gaps in the psychological and participatory dimensions, proposing their integration into future urban regeneration frameworks. This work provides an updated conceptual foundation for sustainable architectural interventions and emphasizes the need to expand research in diverse geographical contexts, particularly in Latin America. Full article

Particulate matter (PM) originating from road dust is an increasing concern in urban air quality, particularly as non-exhaust emissions from tire–pavement interactions gain prominence. Existing models often focus on meteorological and traffic-related variables while oversimplifying pavement surface characteristics, limiting their applicability across diverse spatial and traffic conditions. This study investigates the influence of concrete pavement macrotexture—specifically the Mean Texture Depth (MTD) and surface wavelength—on PM₁₀ resuspension. Field data were collected using a vehicle-mounted DustTrak 8530 sensor following the TRAKER protocol, enabling real-time monitoring near the tire–pavement interface. A multivariable linear regression model was used to evaluate the effects of MTD, wavelength, and the interaction between silt loading (sL) and PM₁₀ content, achieving a high adjusted R² of 0.765. The surface wavelength and sL–PM₁₀ interaction were statistically significant (p < 0.01). The PM₁₀ concentrations increased with the MTD up to a threshold of approximately 1.4 mm, after which the trend plateaued. A short wavelength (<4 mm) resulted in 30–50% higher PM₁₀ emissions compared to a longer wavelength (>30 mm), likely due to enhanced air-pumping effects caused by more frequent aggregate contact. Among pavement types, Transverse Tining (T.Tining) exhibited the highest emissions due to its high MTD and short wavelength, whereas Exposed Aggregate Concrete Pavement (EACP) and the Next-Generation Concrete Surface (NGCS) showed lower emissions with a moderate MTD (1.0–1.4 mm) and longer wavelength. Mechanistically, a low MTD means there is a lack of sufficient voids for dust retention but generates less turbulence, producing moderate emissions. In contrast, a high MTD combined with a very short wavelength intensifies tire contact and localized air pumping, increasing emissions. Therefore, an intermediate MTD and moderate wavelength configuration appears optimal, balancing dust retention with minimized turbulence. These findings offer a texture-informed framework for integrating pavement surface characteristics into PM emission models, supporting sustainable and emission-conscious pavement design. Full article

As coal’s share in primary energy consumption wanes, the annual increase in abandoned coal mines presents escalating safety and environmental concerns. This paper delves into cutting-edge models and attributes of integrating pumped storage hydropower systems with subterranean reservoirs and advanced wastewater treatment facilities within these decommissioned mines. By utilizing the expansive underground voids left by coal extraction, this method aims to achieve multifaceted objectives: efficient energy storage and generation, reclamation of mine water, and treatment of urban sewage. This research enhances the development and deployment of pumped storage technology in the context of abandoned mines, demonstrating its potential for fostering sustainable energy solutions and optimizing urban infrastructure. This study not only facilitates the progressive transformation and modernization of energy cities but also provides crucial insights for future advances in ecological mining practices, energy efficiency, emission mitigation, and green development strategies in the mining industry. Full article

As urban rail transit networks age, understanding the synergistic impacts of multi-defect interactions on tunnel structural safety has become critical for underground infrastructure maintenance. This study investigates defect interaction mechanisms in shield tunnels and cross passages of Beijing Metro Line 8, integrating field monitoring, numerical simulations, and Bayesian network analysis. Long-term field surveys identified spatiotemporal coupling characteristics of four key defects—lining leakage, structural voids, material deterioration, and deformation—while revealing typical defect propagation patterns such as localized leakage at track beds and drainage pipe-induced voids. A 3D fluid–solid coupling numerical model simulated multi-defect interactions, demonstrating that defect clusters in structurally vulnerable zones (e.g., pump rooms) significantly altered pore pressure distribution and intensified displacement, whereas void expansion exacerbated lining uplift and asymmetric ground settlement. Stress concentrations were notably amplified at tunnel–cross passage interfaces. The Bayesian network risk model further validated the dominant roles of defect volume and burial depth in controlling structural safety. Results highlight an inverse correlation between defect severity and structural integrity. Based on these findings, a coordinated maintenance framework combining priority monitoring of high-stress interfaces with targeted grouting treatments is proposed, offering a systematic approach to multi-defect risk management that bridges theoretical models with practical engineering solutions. Full article

Urban voids, such as vacant lots, brownfields, fallow land, wasteland, and the spaces between buildings, have the potential to serve as habitats for a diverse range of plants. However, their value for plant conservation remains understudied because of their informal and neglected nature. The aim of this systematic review is to consider the potential for urban voids to contribute to urban plant biodiversity. A total of 55 studies from 14 countries were analysed for geographical trends, factors influencing plant biodiversity, research methods, and relevant environmental parameters. The results of this study show that the factors influencing the plant diversity of urban voids can be divided into three main categories: biophysical, temporal, and landscape factors. Biophysical factors, such as size, age, soil, and vegetation structure, as well as temporal factors, including site management and human interventions, are the most important at the site-level scale. In contrast, landscape factors, such as the location and distance from other green spaces, are more dominant at the larger urban scale. The review has identified a significant limitation in the available literature, with relatively few studies examining the influence of urban voids’ shape, ownership, and microclimate on biodiversity. With respect to research methods, the results suggest a recent increase in the use of GIS-based and remote sensing techniques to investigate the plant diversity of urban voids. The findings discussed in this paper indicate the need for further research to comprehensively understand the factors that promote urban vegetation diversity in urban voids. Full article

Urban regeneration in historic city centers often encounters tensions between planning strategies, public expectations, and heritage preservation. This study examines the redevelopment process of Sant’Ana Hill in Lisbon, a site historically occupied by many hospitals now subject to closure and adaptive reuse. The transformation of all this 16-hectare area has sparked significant public contestation, highlighting governance challenges and the role of citizen engagement in shaping urban futures amid socio-political and ecological shifts. Using a case study approach, this research draws on urban planning documents, public debate records, media coverage, and semi-structured interviews to analyze the political, social, and architectural dimensions of the regeneration process. Findings reveal that prolonged decision-making, opaque governance, and inadequate public participation have fueled uncertainty, delaying project implementation and increasing public skepticism. The study argues that inclusive participatory frameworks and transparent governance are essential to mitigating conflicts in urban redevelopment. This research also contributes to debates on urban voids, adaptive reuse, and participatory planning, offering insights into the dynamics of contested regeneration in historic districts. Lessons from Sant’Ana Hill highlight the need for a more integrated, democratic, and heritage-conscious approach to large-scale urban transformation projects. Full article

Following World War II, the swift economic growth in construction and the soaring demand in urban regions led to the excessive extraction of natural resources like fossil fuels, minerals, forests and land. To tackle significant global challenges, including the consumption of natural resources, air pollution and climate change, radical changes have been suggested over the past decades. As part of this strategic initiative, prioritizing sustainability in construction has emerged as a crucial focus in the design of all projects. In order to identify the most environmentally sustainable reinforced concrete (RC) slab system, this research investigates the carbon emissions associated with various slab systems, including solid, voided slabs and precast floor systems. The results demonstrate that beam and slab floor and solid slabs have the highest embodied carbon due to the significant use of concrete and related materials, whereas voided slabs and two-way joist floors exhibit lower carbon emissions. The results indicate that the two-way joist system is the most environmentally advantageous option. For precast floor systems, post-tensioned concrete and hollow-core slabs demonstrate the lowest embodied carbon levels. This research provides practical recommendations for architects and engineers aimed at enhancing sustainable design methodologies. It emphasizes the importance of incorporating low-carbon materials as well as pioneering flooring technologies in upcoming construction initiatives to support the achievement of global sustainability objectives. Full article

In the context of global climate change, carbon emission trading (CET) has become a critical tool for driving urban green economic transformation. Since 2011, China has launched CET pilot programs, supporting the achievement of the “dual carbon” goals. Studying the relationship between CET and urban green economic efficiency is essential for advancing urban green economic transitions. However, the existing research is limited by its single-perspective approach, insufficient exploration of mechanisms, and weak heterogeneity analysis, which restricts a comprehensivethe comprehensiveness of our understanding of policy effects. To address these gaps, this study is the first to integrate macro-regional data with micro-enterprise behavior, evaluating the impact of CET on urban green economic efficiency from a dual macro–micro perspective, thereby filling the research void in macro–micro data integration. At the macro level, this study employs panel data from 281 Chinese cities spanning 2007 to 2020, using fixed-effects and difference-in-differences (DID) models to assess the impact of CET on urban green economic efficiency. At the micro level, a game-theoretic pricing decision model is constructed to reveal behavioral differences among enterprises in complete and incomplete information markets and their indirect effects on green economic efficiency. The findings indicate that CET significantly enhances urban green economic efficiency, with technological innovation, green finance, and industrial structural upgrading serving as mediating mechanisms. Heterogeneity analysis shows that the effects are more pronounced in eastern, non-resource-based, small-to-medium-sized, and non-old industrial cities. The game-theoretic model further demonstrates that enterprises in complete information markets more effectively indirectly enhance green economic efficiency through CET mechanisms. By combining macro and micro perspectives, this study provides a new theoretical framework and practical insights for understanding the policy effects of CET. However, limitations such as data confined to Chinese pilots and model simplifications remain. Future research should expand data dimensions, allowing researchers to more comprehensively evaluate policy outcomes. Full article

Ground fissures are extraordinary urban geological disasters, and their harmful effects on underground structures have been highlighted in many cities. Differential settlements between strata can cause a void phenomenon at the bottom of a pipe gallery structure, significantly threatening the project’s construction and operation. This study analyzes the void phenomenon at the bottom of a pipe gallery structure, and a calculation method for the bottom void range is proposed. Through a model test, the stress and deformation laws of the pipe gallery structure under the conditions of orthogonal (90°) and oblique (45°) ground fissure displacements are analyzed. The results show that, owing to the dislocation of the ground fissure, the bottom void range of the pipe gallery is 2.87–3 times the length of the bottom edge of the pipe gallery section under the orthogonal condition and 3.125–3.5 times the length under the oblique condition. Under the dislocation of the ground fissure, the top plate of the structure is under tension; the bottom plate is under compression, and the strains on the side plates are significantly less than those on the top and bottom plates. The maximum contact pressure between the structure and the surrounding soil is distributed on the top plate of the hanging wall and the bottom plate of the footwall near the ground fissure. This study provides a theoretical basis for the optimal design of pipe gallery structures crossing ground fissures and has theoretical significance and application value. Full article

Growing urbanization has increased impermeable surfaces, raising and polluting stormwater runoff, and exacerbating the risk of urban flooding. Effective stormwater management is essential to curb sedimentation, minimize pollution, and mitigate urban flooding. This systematic literature review from the Web of Science and Scopus between January 2000 and June 2024 presents hydrodynamic separation (HDS) technologies. It sheds light on the significant issues that urban water management faces. HDS is classified into four categories: screening, filtration, settling, and flotation, based on the treatment mechanisms. The results show a shift from traditional standalone physical separations to multi-stage hybrid treatment processes with nature-based solutions. The great advantage of these approaches is that they combine different separation mechanisms and integrate ecological sustainability to manage urban stormwater better. The findings showed that future research will examine hybrid AI-assisted separation technologies, biochar-enhanced filtration, and green infrastructure systems. When adopting an integrated approach, the treatment system will perform like natural processes to remove pollutants effectively with better monitoring and controls. These technologies are intended to fill existing research voids, especially in removing biological contaminants and new pollutants (e.g., microplastics and pharmaceutical substances). In the long term, these technologies will help to enforce Sustainable Development Goals (SDGs) and orient urban areas in developing countries towards meeting the circular economy objective. Full article

Urban heritage areas are characterized by unique architectural and cultural elements, often coupled with specific challenges such as vulnerability to climate change and urban heat islands (UHIs). Investigating thermal performance at the neighborhood scale is crucial for preserving these areas while enhancing thermal comfort and sustainability. The aim of this research is to prove that the application of passive cooling techniques and urban green spaces can reduce the urban temperature and upgrade the conditions of thermal comfort, even in densely populated areas with small urban void spaces. ENVI-Met, a microclimate modeling software for evaluating the thermal performance of heritage urban neighborhoods, is applied in order to assess current thermal conditions, identify hotspots, perform simulations, and propose mitigation strategies to improve thermal comfort while preserving the architectural and cultural integrity of these areas. The test bed of this study is a historical urban area in central Athens, “Academia Platonos”. The methodology is mainly based on the design of different parametric scenarios for the study area, by integrating specific parameters that characterize the area of Academia Platonos (elevation distribution, materials, vegetation, etc.) and the microclimatic simulations of the area, designed in the digital environment of ENVI-Met. Five scenarios are implemented and studied in the study area, four of which are based on the existing situation of the study area, either by changing the construction materials of the built environment (passive cooling through cool material techniques) or by enhancing the area with vegetation. One of the most important findings of this study is that the use of plants with a high foliage density is more effective in reducing air temperature than the selection of species with sparse foliage. Full article

The geological study area is volcano-tectonic in nature. Microscopic observations and mineralogical analyses revealed the presence of allophane and diatom clusters whose mineral compositions coincided with weathered andesites and dacites. Edometric consolidation tests showed a high porosity and a reduction in the void ratio by up to five times. These are highly compressible soils with a Cc/Cs ratio of 12 to 15 and a specific gravity (Gs) of 2.4. Low initial bulk density (1.10 Mg/m³), high plasticity, and SUCS (OH) classification are typical of soft soils, with an effective friction angle (ɸ’C_D) of 25.5° to 30° and effective cohesion (c’_CD) of 11.90 to 47.27 KPa. The shear wave velocity for the first 10 m (Vs10) on average ranged from 78 m/s to 120 m/s, whereas that for the first 30 m (Vs30) was 169 m/s. The permeability, which was calculated indirectly, was between 2 × 10⁻⁷ and 3 × 10⁻⁸ m/s. With an organic matter content between 5% and 25%, the Caupicho soil is an organic mineral sediment that is not considered peat (non-peat). The results of this study serve as a basis for future analyses of soil dynamics, bearing capacity, and consolidation settlements in the medium and long term in an area of high urban growth in southern Quito, Ecuador. Full article

In recent climate-adaptive design strategies, there has been a growing interest in creating healthy and comfortable urban microclimates. However, not enough attention has been paid to the influence of street interface morphology in order to better understand the wind–thermal conditions of various commercial streets within the city and create a sustainable built environment. This research summarizes and categorizes commercial streets according to their functions and types of attributes and then abstracts the ideal models of three types of typical commercial streets to explore the effects of changes in specific morphological parameters on their wind–thermal environments. Firstly, this study selects out design parameters that affect the street interface morphology. Then, it uses the numerical simulation software PHOENICS2019 to simulate and investigate the effects of three types of typical commercial street interface morphology on their wind environment and thermal comfort. The results show that (1) in neighborhood-commercial streets, reducing void ratio and variance of height fluctuations can enhance the average wind speed of the street while reducing average temperature and improving the thermal comfort; (2) in business-office streets, the value of the void ratio is negatively correlated with the wind environment and thermal comfort, while the changes in the variance of height fluctuations and the average aspect ratio are positively correlated; and (3) in comprehensive-commercial streets, the decrease of the void ratio will reduce the average wind speed of its street and increase the average temperature, thus weakening the thermal comfort of pedestrians. In contrast, the variance of height fluctuations as well as the average aspect ratio do not significantly affect its wind–thermal environment. These conclusions from this research provide a theoretical basis and methodological reference for the creation of safer, resilient and sustainable built environments. Full article

This study introduces soil squeezing technology (SST) as an innovative approach to soil improvement that addresses the limitations of conventional methods in urban geotechnical projects. Unlike traditional in situ mixing, SST uses displacement, compaction, and controlled solidification to effectively increase soil cohesion and strength while reducing voids. By minimizing reliance on large mixing plants and bulky machinery, SST offers significant advantages in confined urban spaces, providing accessibility and operational efficiency. This paper describes the mechanism of SST, field application procedures, and adaptability to different soil types including humus and organic-rich soils. The compaction-driven approach ensures the consistent formation of dense, high-strength columnar soil structures, even in challenging geotechnical environments. Field studies demonstrate SST’s superior bearing capacity, uniformity, and reduced site disturbance compared to conventional methods, making it suitable for modern infrastructure. Quality control through real-time inspection further highlights the operational reliability of SST. This research underscores SST’s potential as a cost-effective, scalable solution that meets the stringent demands of urban development while minimizing environmental impact and optimizing resource use. Full article