Trialog 152/153 Subterranean Solutions for Climate Resilient Future

As urban centres worldwide continue to confront the escalating challenges posed by climate change, rapid population growth, and the complexities of urbanisation, there is an urgent need for innovative, sustainable, and resilient solutions. Among the most promising yet often underexplored potential solutions is that of subterranean spaces. These hidden layers beneath our cities offer new opportunities to rethink how we design, manage, and adapt urban spaces to meet the demands of a rapidly changing environment. This thematic issue of TRIALOG explores how subterranean spaces can be harnessed to foster climate resilience, offering a comprehensive exploration of their possibilities and the interdisciplinary approaches required for their integration into contemporary urban planning.

Subterranean spaces – often relegated to tunnels, basements, and utility infrastructur – have long been seen as a utilitarian, subordinate aspect of urban planning and design. However, as cities struggle with the challenges of urban sprawl, overcrowding, and climate-related stresses such as flooding, heatwaves, and rising sea levels, these underground areas present untapped potential for creating sustainable, multifunctional spaces that can alleviate pressure on already overburdened urban surfaces. From energy-efficient infrastructure to mitigating the urban heat island effect, subterranean spaces can serve as a critical tool in building more-resilient cities that can withstand the impacts of climate change while enhancing urban liveability.

This issue seeks to elevate the conversation around subterranean spaces by exploring their role in promoting urban climate resilience. It examines both the opportunities and challenges that come with incorporating underground spaces into urban strategies, from technical feasibility and design innovation to environmental, social, and governance considerations. As cities continue to evolve and adapt to climate risks, it is essential to question how we can create spaces that are not only functional but also inclusive, equitable, and beneficial to diverse urban populations. How can we ensure that subterranean development meets the needs of all citizens? What role do policy and governance play in facilitating or hindering the widespread adoption of subterranean solutions? And how can interdisciplinary collaborations between urban planners, architects, engineers, and scientists shape these spaces in a way that benefits both people and the planet?

Part I of this issue sets the stage for a deeper understanding of the role subterranean spaces can play in creating climate-resilient cities. Contribution by Han Admiraal offer critical reflections on the environmental, ethical, and socio-economic considerations that should guide the design and use of underground spaces. These articles challenge conventional approaches and provide a roadmap for integrating subterranean spaces into broader urban resilience strategies. Antonia Cornaro and Annika Lundkvist further expand on these ideas, advocating for an interdisciplinary and experiential approach to subterranean design that considers not only technical specifications but also the human experience and social dynamics that must be taken into account for successful integration.

Part II shifts the focus to case studies and real-world examples that demonstrate the practical applications of subterranean spaces in urban settings. Contributions from Maria de Lourdes Melo Zurita, Loretta von der Tann, and Daniel Boddice offer valuable insights into the growing importance of mapping underground spaces, highlighting how cities can better understand, monitor, and manage these crucial resources. By leveraging data, cities can unlock new possibilities for sustainable development while ensuring that subterranean spaces are used efficiently and effectively. Rosina Vinyes-Ballbé and Jean Louis Missika’s examination of Paris and Barcelona illustrates how underground spaces are being re-imagined not just as transportation corridors but also as vibrant public spaces that contribute to the social, cultural, and economic vitality of the city. This section also features Michael Kompatscher’s insights into the Hagerbach Experience, which highlights the technical challenges and opportunities of working in underground environments.

Other case studies delve into more specialised applications of subterranean spaces. Asal Bidarmaghz and Julieta Rottemberg offer a compelling look at the role of underground spaces in energy infrastructure, demonstrating how tunnels and subterranean systems can help optimise energy distribution and storage, vital components for sustainable urban development. Michael Robert Doyle’s article, which connects city models and artificial intelligence (AI) with underground spaces, takes the reader into the realm of the future, where urban undergrounds are not only mapped and managed but are also integrated into smart city frameworks.

Part III explores innovations and visionary ideas that push the boundaries of subterranean design. Giorgio Orsucci offers a thought-provoking examination of the design paradigms that could shape the underground cities of tomorrow, focusing on how emerging technologies and sustainable design principles can transform subterranean spaces into liveable, functional environments. Joyce van den Berg and Ingrid Oosterheerd’s work on restoring soil biodiversity further enriches the conversation, illustrating how subterranean development can be integrated with ecological restoration efforts to enhance both urban and environmental health. These contributions underscore that subterranean spaces are not just a technical solution to urban challenges, but are part of a broader vision for sustainable, healthy, and resilient cities.

Taken together, the articles in this issue build a compelling case for the importance of subterranean spaces in urban resilience. They demonstrate that underground spaces offer a powerful means to mitigate the impacts of climate change while also enhancing the quality of urban life. However, the development of these spaces requires careful planning, innovative design, and collaboration across disciplines. From the governance frameworks that support or hinder subterranean development to the technical and environmental challenges that must be addressed, this issue of TRIALOG highlights the complexity and potential of subterranean spaces and sets the stage for continued research and exploration.

The journey towards integrating subterranean spaces into our cities is not without its challenges, but the potential rewards – ranging from flood management and energy efficiency to enhancing urban biodiversity and creating inclusive public space – are too great to ignore. As cities worldwide face mounting climate pressures, the underground is emerging as an essential frontier for innovation and sustainability. By embracing the potential of subterranean spaces, we can create urban environments that are not only more resilient to climate risks but also more equitable, inclusive, and capable of thriving in the face of future challenges.

This issue of TRIALOG serves as a call to action for urban planners, policymakers, engineers, architects, and researchers to continue pushing the boundaries of what is possible with subterranean spaces. Through collaboration, creativity, and commitment to sustainability, we can unlock the full potential of the underground and shape the climate-resilient cities of the future. We hope that this collection of articles will inspire new discussions, research, and innovations in subterranean urbanism, ultimately contributing to the creation of cities that are better equipped to meet the challenges of the Anthropocene.

Mahak Agrawal