An ad hoc committee of the National Academies will conduct a study to summarize current geoengineering knowledge about underground development in the urban environment; identify pressing research needed to take advantage of opportunities for enhancing urban sustainability through underground development; and develop an enhanced public and technical community understanding of the role of geoengineering in the sustainability of the urban built environment, specifically through the minimization of consumption of nonrenewable energy resources, construction materials, and negative impact on the natural, built, and social environments. Issues to be addressed include geologic site characterization, construction and geotechnical monitoring techniques, energy requirements and benefits, and lifecycle costs and benefits of sustainable underground infrastructure development. The study will recommend directions for a new geoengineering research track focused on earth systems engineering and management to ensure future human resources for sustainable underground development. Advantages and disadvantages of establishing a new research center in this area will be analyzed, and other potential options for enhancing the human resource capacity for sustainable underground development -including the status quo- will be considered. The policy, economic, and human behavioral drivers that promote or inhibit the development of the subsurface in a sustainable manner will also be considered from a social science point of view.
Underground infrastructure can help preserve surface space, provide climate or security containment, reduce above ground congestion, and provide aesthetic benefits. An ad hoc committee of the National Research Council explored how underground engineering contributes to a sustainable urban environment and provided a framework for interdisciplinary research, training, education, and practice in underground engineering that will increase capacity and support U.S. security, public and environmental health, and quality of life. Research that could enhance underground engineering practice is suggested. Underground infrastructure (e.g., subsurface sewers; power and communication lines; and transportation tunnels) is rarely engineered in consideration of the interdependencies between other underground or surface infrastructure. Its contributions to long-term societal sustainability—increasingly important as populations increase, climate changes, and more demands on infrastructure increase are often not part of decision making. Underground facilities may require seemingly cost-prohibitive initial investments for construction when compared to similar surface projects. The economic, environmental, social, and aesthetic benefits of placing infrastructure underground are difficult to quantify. Comprehensive and scientific studies to retrospectively assess the costs and impacts of various types of underground projects on sustainability could help evaluation of new project impacts and usefulness and inform decisions related to long-term operation and maintenance of underground projects. As cities become more densely developed and underground use expands, careful planning of underground space and infrastructure are increasingly important. New underground infrastructure may help redirect urban development into more sustainable patterns. However, U.S. conventions tend to recognize the value of only surface space, and there is little strategic coordination of above and underground infrastructure development. Planning decisions are influenced by political, social, and economic factors with minimal consideration of long-term maintenance or societal needs. This is, in part, due to the lack of a mission agency or organization dedicated to coordinating development activities across sectors. A sustainable urban environment is recognized as a system of interconnected systems that allows efficient and sustainable service delivery. Expanded and coordinated communication with stakeholders (e.g., urban planners, architects, and engineering, geologic, and environmental specialists) to better incorporate site-specific conditions, greater engineering flexibility, and long-term community needs into optimal infrastructure design and management is needed. A federally-led, interdisciplinary network of organizations and institutions could encourage communication, better understanding of the ownership of underground space, and the development of guidelines for funding and performing essential periodic inspections, maintenance, and repair of infrastructure elements. The U.S. was a once world leader in technology related to underground space development. Industry and academic research collaborations contributed to a continuous flow of ideas and helped create a U.S. workforce and industry leaders. That leadership is retiring with few able to replace them. Federal and industry investment in underground engineering research and development has waned, and most underground construction innovation now comes from outside the U.S. This has potentially negative impacts on U.S. economic growth and global competitiveness. Limited investment has also led to a significant reduction of U.S. university programs dedicated to underground engineering research and education, and a critical shortage of opportunities for engineers wishing to learn and practice in the U.S. Training is now obtained mostly through mentoring and on-the-job. This can benefit the workforce, but competitiveness and liability concerns can limit information sharing and exposure of young engineers to a range of technologies. Even the best-designed underground infrastructure deteriorates, and state-of-the-art technologies become obsolete. Long-term commitment to maintenance, to keeping abreast of technological advancements, and being prepared for the impacts of changing climate and societal needs is essential for sustainability. For example, designing infrastructure that allows ease of access for inspections, maintenance, repairs, upgrades, or reconfigurations in response to new needs or new technologies facilitates lower costs. Additionally, risk-informed approaches to project planning and design—balancing lifecycle project needs in terms of service delivery, initial costs, resilience against extreme events, and effective maintenance and operations—can result in improved infrastructure performance. Underground space can be designed to be as safe, attractive, and functional as above-ground structures. Few federal-level safety regulations specifically address underground infrastructure, and those that do mostly apply to construction, rather than to operational usage. Developing performance-based safety mechanisms and codes that account for today’s underground occupancies as well as expansion and change in use could ensure safety and increase public acceptance of underground space. The committee’s report is available for free download at www.nap.edu/catalog.php?record_id=14670. Over 1200 copies have been downloaded. There is a need to expand our knowledge of engineering technologies that align technical tools, collective perceptions, public policies, regulations, and procedures to reduce risk, and create services and spaces that function reliably. Implementation of recommendations in this report could lead to new patterns in interdisciplinary education, training, research, and practice that could increase U.S. capacity to create and maintain urban areas that improve and sustain high quality of life.
