Delivering Sustainable Infrastructure that Supports the Urban Built Environment C A R O L B O Y L E * The University of Auckland, New Zealand G A V I N M U D D Monash University, Clayton, Victoria, Australia J A M E S R . M I H E L C I C University of South Florida, Tampa P A U L A N A S T A S Yale University, New Haven, Connecticut T E R R Y C O L L I N S Carnegie Mellon University, Pittsburgh, Pennsylvania P A T R I C I A C U L L I G A N Columbia University, New York M A R C E D W A R D S Virginia Polytechnic Institute and State University, Blacksburg, Virginia J E R E M Y G A B E Landcare Research, Auckland, New Zealand P A T R I C I A G A L L A G H E R Drexel University, Philadelphia, Pennsylvania S U S A N H A N D Y University of California Davis, California J E H N G - J U N G K A O National Chiao Tung University, Hsinchu City, Republic of China S U S A N K R U M D I E C K University of Canterbury, Christchurch, New Zealand L I O N E L D . L Y L E S Southern University, Baton Rouge, Louisiana I A N M A S O N University of Canterbury, Christchurch, New Zealand R O N M C D O W A L L The University of Auckland, New Zealand A N N I E P E A R C E Virginia Polytechnic Institute and State University, Blacksburg, Virginia C H R I S R I E D Y University of Technology, Sydney, Australia J O H N R U S S E L L La Trobe University, Melbourne, Australia J E R A L D L . S C H N O O R University of Iowa, Iowa City M A Y A T R O T Z University of South Florida, Tampa R O G E R V E N A B L E S Crane Environmental Ltd, Surrey, U.K. J U L I E B . Z I M M E R M A N Yale University, New Haven, Connecticut V A L E R I E F U C H S Michigan Technological University, Houghton S A R A H M I L L E R Yale University, New Haven, Connecticut S H A N N O N P A G E University of Canterbury, Christchurch, New Zealand K A R E N R E E D E R - E M E R Y Southern University, Baton Rouge, Louisiana Sustainable living will require megacity-level infrastructural support designs and paradigms. TRISH CULLIGAN Environ. Sci. Technol. 2010, 44, 4836���4840 4836 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / VOL. 44, NO. 13, 2010 10.1021/es903749d ��� 2010 American Chemical Society Published on Web 06/29/2010

Over 50% of the global population now lives in urban areas (1). Over the past century, urban areas have expanded at a greater rate than population growth, increasing requirements for resources and producing greater impacts on the natural environment. Urban societies have also changed, with a greater diversity of cultures, high population densities, and rising demand for services, resulting in an increasing complexity of human urban systems. Urban systems influ- ence and are influenced by infrastructure systems, which affect the design and management of the built, social, and natural environments, including future infrastructure deci- sions. Sustainable infrastructure that supports the built envi- ronment is essential for the survival and health and wellbeing of a society. The built environment includes buildings, engineering works, and infrastructure such as roads, waste- water and water treatment plants, stormwater management systems, power generation facilities, railways, bridges, and even natural systems such as rivers and harbors. Infrastruc- ture systems provide the basic physical structures needed for the operation of a society and facilitate access to goods and services. There is already significant awareness of and action focused on urban sustainability. Green building standards have promoted life cycle thinking in design and manufacture of materials and products and have raised community-level awareness of infrastructure considerations and operational characteristics associated with buildings. Low impact design (LID) of infrastructure, which reduces environmental impact, is now being incorporated into urban developments. Life cycle and impact assessments of materials and infrastructure systems together with material flow and urban metabolism studies are improving understanding of resource use and informing needs for future infrastructure design, construc- tion, and management (2-6). Yet it is not clear if these approaches will deliver sustainable infrastructure (7). There is an increasing awareness that cities function as complex, dynamic urban ecosystems (8) and that infrastruc- ture is critical in delivering sustainable cities. Thus major shifts in planning, decision making and implementation will be needed to address the challenge of urban sustainability. Developing sustainable infrastructure systems will require a greater understanding of their complexity and dynamics, using an interdisciplinary approach. This paper presents the results of a multidisciplinary, international workshop that identified ��� challenges in developing and managing sustainable infrastructure which need to be addressed by research ��� priorities for research into the urban built environment that are necessary to achieve sustainable infrastructure. Workshop The workshop was attended by 28 researchers from the U.S., U.K., Australia, Taiwan, and New Zealand, with expertise in green buildings, geotechnical engineering, water manage- ment, construction, sustainable design, urban design and infrastructure, energy, climate change, transportation, de- veloping countries, mining, public policy, and chemistry. Presentations on urban infrastructure challenges were fol- lowed by a discussion on the research issues that were seen as priority. Key research themes were then identified and developed in greater detail. Urban Infrastructure Challenges. Challenges in devel- oping a framework to deliver sustainable infrastructure include the following: ImprovingUnderstandingofSustainability. Whiletheterm ���sustainability��� has been used for many purposes, the science underpinning it is unclear. The Brundtland (9) definition of ���Ensuringtheneedsofthecurrentgenerationaremetwithout compromising the needs of future generations���, despite its many interpretations, is still fundamental. Overall, however, there is agreement that inter- and intragenerational equity and the sustainability of environment and society are important. Most researchers agree that an ecosystems thinking approach, recognizing the complex, multiscale, dynamic nature of human and ecological systems, is essential for achieving sustainability (8, 10-14). The role of resilience in complex system function and in achieving sustainable systems has been widely debated (11,12,14-16). However, there is still contention with respect tomeasuringresilience,effectivewaysofincreasingresilience in systems, and whether resilience alone can deliver sustain- able human systems (10). Even the factors which make a system resilient have yet to be identified (17). Research is now focusing on better understanding complex, sociotech- nical systems, such as urban infrastructure, and their sustainability. GlobalWarming. Global warming models predict possible changes in temperature, precipitation patterns, storm surges, increases in sudden, catastrophic weather events, and in sea levels (18, 19). The ramifications for infrastructure are significant and will affect planning, designing, operating, maintaining, and upgrading of infrastructure. Many cities, such as London, are constructing greater flood protection to meet model predictions. The impact of Hurricane Katrina on New Orleans is a timely warning of a city inherently vulnerable to extreme weather events. Increased Urbanization. Most of the 3 billion people projected to be added to the global population over the next 50 years will reside in cities (20). The number of megacities (population 10 million) has increased from 3 in 1975 to 19 in 2007 by 2025, this number is expected to rise to 27, with 6 cities projected to have populations over 20 million (20). There is limited understanding of the complexity and risks of the large-scale infrastructure systems being developed to serve megacities. However, the criticality of providing suf- ficient resources so as to prevent social unrest and conflict makes sustainable megacity infrastructures especially vital. Increasing Age and Risk of Failure in Urban Infrastructure. Many of the major cities in Europe and North America have road, sewer, and water infrastructure systems that combine century old infrastructure with upgraded or new construction and technology. Such systems may fail as the capability and resources to maintain them vanishes. The American Society of Civil Engineering���s 2009 Infrastructure Report rates U.S. infrastructure systems with an overall grade of D solid waste ranked highest at C+, and water, wastewater, roads, levees, and waterways all received D- (21). The estimated financial investment required for infrastructure upgrading for the U.S. is $2.2 trillion over five years. Increase in Consumption in Developing Countries. While the per capita consumption of developing countries remains below that of the developed world, population, consumption, and subsequent economic growth in China and India are increasing rapidly. These increases are driving consumption of natural resources both locally and internationally, causing escalating impacts on environments and societies across the globe. Resource Availability: Energy, Water, and Construction Materials. Peak oil (the point of maximum global oil production), declining oil supplies (22), and increasing severe water scarcity (annual water supplies below 1000 m3/person) (1) will have major impacts on the production and supply of food, water, electricity, transportation, communication, andmostconsumergoods.Therearealsosignificantconcerns about the growing environmental footprint of mining (23,24) increasing demands for metals and other materials will only add to those concerns. VOL. 44, NO. 13, 2010 / ENVIRONMENTAL SCIENCE & TECHNOLOGY 9 4837