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Engineering and Environmental Challenges: Technical Symposium on Earth Systems Engineering Urban Design The Grand Challenge LAWRENCE T. PAPAY In February 2000, as part of Engineers’ Week, I addressed the D.C. Council of Engineering Societies. In my talk, I referred to the National Academy of Engineering’s (NAE’s) list of the top 20 engineering achievements of the twentieth century and predicted what I thought the engineering challenges in the twenty-first century would be, especially (1) the development of complex systems, particularly as they apply to infrastructure, and (2) sustainability. These two challenges are components of a greater challenge—urban design. If we consider the 20 greatest achievements of the past century (Table 1), we are struck by the number that deal with processes, services, and conveniences we associate with urban living. These include electrification, the automobile, TABLE 1 The 20 Greatest Engineering Achievements of the 20th Century 1. Electrification 11. Highways 2. Automobile 12. Spacecraft 3. Airplane 13. Internet 4. Water supply and distribution 14. Imaging 5. Electronics 15. Household appliances 6. Radio and television 16. Health technologies 7. Agricultural technologies 17. Petrochemical mechanization 8. Computers 18. Laser and fiber optics 9. Telephone 19. Nuclear technologies 10. Air conditioning and refrigeration 20. High-performance materials Source: NAE, 2000.
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Engineering and Environmental Challenges: Technical Symposium on Earth Systems Engineering agricultural technologies, water supply and distribution, and health technologies. These achievements have certainly improved the quality of life for everyone in the twentieth century. In addition, they have accelerated the massive global shift of populations to urban centers. In this country, 50 percent of the population was engaged in farming at the turn of the previous century in contrast to 2 percent today. A century ago, cities with a million inhabitants were rarities; today megacities of 10 million are becoming all too common, mostly in countries that are ill-equipped to handle these large concentrations of people. Urban centers are an important focus area for Earth systems engineering because they have impacts that extend far beyond their urban centers. For example, large cities create their own microclimates through local changes in albedo (light reflection), heat generation, and humidity. And their waste streams can pollute local and regional bodies of water, even such large areas as the Bay of Bengal. Cities rely not only on technologies and infrastructural concepts of the twentieth century, but also on those of the nineteenth century. To compound the problem, cities, regions, and nations spend a good portion of their gross national products enlarging, modifying, and repairing this infrastructure without examining whether the fundamental design of urban systems is appropriate or whether new approaches might be more effective. As cities grow, the size, complexity, cost, and, scale of existing technologies used to transport goods and services must be reexamined. Urban centers should be designed to meet the needs of tomorrow. As an example, let’s look at water supply and distribution and their complements, wastewater and sewage. The provision of a potable water supply and reliable distribution have been major accelerants to the expansion of urban centers. About 200 years ago, as cities in the United States began to grow, they had to look beyond local ponds, wells, and cisterns for water supplies. In 1801, Philadelphia was the first U.S. city to install a water system; Cincinnati soon followed in the 1820s, New York in 1841, and Boston in 1848. By 1860 the 16 largest cities in the United States had installed a total of 136 water systems (NRC, 1984). The realization of abundant (if not unlimited) water supplies enabled cities to switch technologies from the use of privy vaults, cesspools, and private sewers for wastewater and sewage disposal to a technology that used large amounts of water as the medium for diluting and transporting wastes beyond the city boundary. In the intervening years, the main supplement to these systems has been the treatment of wastewater streams before discharge. In 1850, or even 1950, this approach might have been acceptable. But we must ask ourselves if it is the best approach for the twenty-first century megacity? If we could go back to square one and systematically examine the use of water and the disposal of wastes, would we choose to use existing technologies? Can we afford to use freshwater, our most critical resource, as a medium for diluting and transporting waste and then turn around and treat this high-volume stream to make it acceptable for discharge into the environment? Should we create more
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Engineering and Environmental Challenges: Technical Symposium on Earth Systems Engineering dual water systems? For example, should potable water be supplied in containers and existing water systems be converted to gray water only? Should we rely on chemical or biochemical treatments of waste treatment to reduce the need for freshwater as a dilutant and transport medium? And should we consider using modular, smaller-scale treatment systems complete with local recycling or integrate treatment systems into systems that meet other needs, such as electricity and heat? I have used water as an example, but I could just as well have used power or communications or transportation. Large-scale networked infrastructures will not necessarily be a wise choice for future, megascale urban development in any of these arenas. The grand challenge for engineers designing future urban centers, then, is to understand the patterns of the supply and use of energy, materials, products, information, and services that underlie urban systems. This information would enable us to select (or develop) technologies on a scale appropriate for various activities and elements of infrastructure. In short, we must begin to think outside the box. In tackling this grand challenge, engineers must address a number of key questions: Will more stringent environmental and safety requirements limit the technical options in certain economic sectors but increase the options in other sectors? Should we look for alternative methods of waste disposal or recycling? What is the preferable scale for recycling various commodities and materials for different elements of urban infrastructure? For example, should water recycling systems be implemented on a building/neighborhood scale, and if so, should this be done vertically or horizontally? That is, should water cascade through systems at poorer and poorer quality (i.e., vertical use), or should it be recycled for uses that require equivalent water quality (i.e., horizontal use)? Can we capture and reuse waste heat and chemical energy? Is industrial agriculture environmentally efficient compared with, say, “apartment complex gardening systems”? Should we focus on technologies for power and communications that can provide reliable service without massive, hard-wired infrastructures? Does “homeland defense” require new paradigms for urban infrastructure? Introducing new technologies that are likely to disrupt old infrastructures is much more difficult in older urban areas than in developing countries that have less existing infrastructure. Existing cities can be changed only incrementally, because inertia is difficult to overcome, particularly for capital-intensive systems. We know how to optimize engineered systems, but if we do not consider their
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Engineering and Environmental Challenges: Technical Symposium on Earth Systems Engineering human dimensions, we will only repeat the failures of the past (e.g., the construction of low-income housing projects in U.S. inner cities). We must look to small-scale examples that have worked, such as Brooklyn Heights and New England villages where self-sufficiency and self-containment have worked together. If we begin to address these problems now, our successors in 2100 will note that in the year 2000, we began a quest to use Earth systems engineering to make significant, beneficial changes in urban design. REFERENCES NAE (National Academy of Engineering). 2000. Greatest Engineering Achievements of the 20th Century. Available online at <http//www.greatestachievements.org>. NRC (National Research Council). 1984. Perspectives on Urban Infrastructure. Washington, D.C.: National Academy Press.
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