FEATURE
Building Smart-Growth Communities City planners are combining traditional and contemporary design principles to preserve open spaces and reduce environmental impacts. JANET
PELLEY
has been proposed as an antidote to the environmental impacts associated with suburban sprawl development. Although experts debate whether this will really provide env i r o n m e n t a l benefits, states are forging ahead with smart-growth experiments in land use policy. What states must determine is what will be the most effective and efficient way to attain these environmental benefits
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prawl, the dominant land-use pattern since World War II, has bloated the boundaries of metropolitan areas with its high per capita rate of land consumption. In the past year alone, a score of states have identified runaway suburban development as one of their most pressing environmental problems. city where neighborhoods are pedestrian-friendly and residents walk to shops and schools or take public transit to work " mused Harriet Tregoning EPA director of urban and economic development In this citv big companies help fund development of
"This may sound futuristic but it is alreadyhappenine in Los Angeles California Portland Oregon and other places across' the country" said Tregonine Between 1970 and 1990 Chicaen and Philadel' phia grew more than 30% in area even though their dh W H I F 1qfint iqqn K
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a golden ring that has been moving away from tiie downtown area at a rate of two miles per decade (i). . . . . . . . , , r Inside the rmg, populatione income, and the number J . PP8*P nv, e e cien opera ion r as social and environmental disintegration. © 1999 American Chemical Society
According to Reid Ewing, consultant with LDR International, sprawl is characterized by commercial strips, large expanses of low-density development that separate residential and commercial land uses, and scattered or leapfrog development well beyond the urban fringe. The indicators of sprawl are poor accessibility, vehicle dependency, and lack of functional open space, he said. Last September, a report from Pennsylvania Governor Tom Ridge's 21st Century Environment Commission blamed sprawl for degraded air and water quality, increased automobile pollution, loss of open space, and decaying urban cores. The commission recommended that local governments be given more power to reduce these environmental, social, and economic impacts. According to Stuart Meek, principal investigator at the American Planning Association in Chicago, III, Pennsylvania is one of more than 17 states that have completed or have just begun rethinking and refining their planning models. Just last year, Maryland passed smart-growth legislation that encourages mixed-use, pedestrian-friendly development inside existing infrastructure and supports conservation of open space. This year, Tennessee approved legislation to establish urban growth boundaries for cities and counties by the year 2000, and New Jersey has proposed to preserve 2 million acres, or 20% of the state. Evaluating air quality impacts "Air quality is degraded by suburban sprawl land-use patterns," said Geoffrey Anderson, an analyst with EPAs Office of Policy. Because developments are located further from city centers and residential areas are separated from shopping and work areas, people are driving more. As a result, whereas the nation's population grows at 1% per year, vehicle miles traveled (VMT) is growing at 3% per year, said Anderson. Between 1970 and 1993, the average VMT per person per year jumped by 41%, thanks largely to increases in trip distances. From 1983 to 1990, the average trip lengthened from 8.68 to 9.45 miles (i). According to Anderson, emissions from vehicles are responsible for one-quarter of nitrogen oxides, carbon monoxide, and volatile organic compounds released each year. And because people are driving more, he predicted that those emissions will continue to rise. But some research suggests that smart-growth land use could reduce VMT and auto emissions. Ewing analyzed travel patterns in one Florida county and found that households in locations with good access to shopping and jobs spent 40 minutes less per day in their cars than households in the least accessible locations. As residential density increases, said Ewing, trips become shorter, more trips are taken on foot or transit, and VMT decreases. Doubling urban density leads to a 15% drop in VMT (2), he said. A new EPA study suggests that locating a community on an urban infill site produces significantly less air pollution than placing the same community on a suburban edge greenfield (3). The study modeled the environmental impacts of the two different sites for three jurisdictions: San Diego, Calif., Montgomery County, Md., and Palm Beach County, Fla.
The connection between development and water quality impacts Two growth scenarios spanning 1995-2020 were modeled to understand environmental impacts on a county in Maryland (borders disguised to maintain anonymity). By focusing development in three out of six watersheds with existing infrastructure, it was found that directed (or smart) growth should conserve significantly more open space, preserve stream quality, and reduce nutrient pollution. (Courtesy, Joseph Tassone, Maryland Office of Planning, Baltimore, Md.)
Development at infill sites, for all three jurisdictions, reduced the average VMT per capita by 4861%, compared with the greenfield site. The model predicted that emissions of smog-producing nitrogen oxides at the infill sites would be reduced by 27-42% and that greenhouse gas emissions would be roughly half the amount generated at the greenfield sites. However, although infill sites in San Diego and West Palm Beach were predicted to benefit from reduced auto travel time and congestion, it was predicted that the JAN. 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS • 2 9 A
while protecting natural resources." From 1970 to 1998, jobs downtown have Nutrient pollution falls grown from 50,000 to 105,000, and air By concentrating growth in areas served by sewer in three watersheds, directed quality has improved from over 100 vigrowth reduces nitrogen loading to water bodies and reduces the number of watersheds olations per year in the 1970s to none impacted. (Courtesy, Joseph Tassone, Maryland Office of Planning, Baltimore, Md.) since 1987 (i). Portland even shifted money designated for two freeways to public transit investments instead, predicting that such smart-growth land use would provide better air quality and a greater reduction inVMT. Proponents of the Portland model, such as Sam Seskin, principal with Parsons Brinckerhoff Quade & Douglas, Inc., a consulting firm in Portland Ore., note that Portland has attained both a. boominsz economy cuid SL reduction inVMT by 7% below what it would have been under conventional growth patterns Despite optimistic forecasts, some assumptions of smart-growth strategies are debatable. Economics professor Peter Gordon at the UniLess pollution per household versity of Southern California questioned the conWhen growth is directed, not only are fewer watersheds impacted, ventional wisdom that an increase in VMT will but the amount of nitrogen released to the environment per new necessarily lead to greater air pollution. He noted that household is roughly one-third the amount released under nondirected vehicle emissions are lowest at speeds around 45 growth. The codes are WWTP (wastewater treatment plant), Septic mph, and argued that because suburban trips are at (septic systems), and Land cover (runoff and groundwater from higher speeds, suburban driving should cause less developed land). (Courtesy, Joseph Tassone, Maryland Office of air pollution. Gordon further remarked that half of Planning, Baltimore, Md.) all vehicle pollutants are generated when the engine is started and when it is turned off, so the number of trips mfly be more important than VMT in predicting levels of air pollution (4). "Pedestrianfriendly 'whatever' has not been shown to make a dent in automobile use" he concluded. "The impact of land use on travel patterns is a very contentious issue," commented Nat Bottigheimer, manager with Hagler Bailly, a consulting firm in Bethesda, Md. He noted that most empirical studies are equivocal on the air quality benefits of smart-growth land use. The factors that influence whether people walk or take public transit, such as the width of sidewalks or the absence of schedules at bus shelters, are at such a fine level of detail that they are difficult for the modMontgomery County site in Silver Spring, Md., would els to capture, he explained. Nevertheless, the EPA study experience dramatically higher levels of congestion and and other studies indicate there is a great potential for longer travel times. But, the study noted, shorter trip land use to impact air quality, said Bottigheimer. lengths at the Silver Spring site would offset the higher level of congestion. Maryland's smart-growth pro- Regulatory experiments gram focuses on financial incentives and avoids a com- According to Tregoning, although air quality has immand-and-control approach. proved because of the regulation of point sources, a In Oregon, rules passed more than 20 years ago growing fraction of air pollution is contributed by nonrequire all cities to create growth boundaries that es- point sources. EPA predicts that within the next eight tablish lines around metropolitan areas, outside of years, gains in air quality from catalytic converters and which, growth is discouraged or prohibited. The Port- reformulated gasoline will begin to erode because of land metropolitan area, which has become a recog- increases in VMT (i). "The challenge is that environnized leader and focal point of the smart-growth de- mental quality improvements that can be made by regbate, adopted its boundary in 1979 and subsequendy ulated point sources are small and expensive," said Trformed a regional government with the power to im- egoning. Big utilities in California cannot carry all the plement land-use policies. [economic costs of] additional air quality improveAccording to Linda Peters, chair of the Washing- ments on their backs because they have already made ton County Board of Commissioners, Portland chan- the large, inexpensive gains, she said. neled its growth along transit lines and promoted reTregoning believes that the vast, untouched arena development that has "created a more neighborly city of individual unregulated sources has a tremendous 3 0 A • JAN. 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY / NEWS
effect on environmental quality and that further management initiatives Smart growth reduces impervious cover could have a huge positive effect. ComWhen growth is nondirected, each of the six watersheds in the county experience panies might, for example, achieve dramatic increases in impervious cover. When better directed, impacts are reduced greater air quality benefits at less cost and are limited to only three watersheds. (Courtesy, Joseph Tassone, Maryland Office by investing in transit or efficient peof Planning, Baltimore, Md.) destrian-oriented developments, rather than pollution controls. She commented that EPA is exploring ways to use regulations to create incentives for land use that reduce vehicle use and promote urban redevelopment. Incentive-based regulations could bring welcome relief for some developers. In Atlanta, Ga., clean air restrictions are hampering road building and could kill an environmentally friendly redevelopment of a brownfield. Developers have proposed building a pedestrian- and public transit-oriented village of 5000 residences, including office and commercial space, on the old Atlantic Steel mill site near downtown Atlanta. To be Another Clinton Administration initiative is lookviable, the project requires that a new bridge be built ing into ways to use the Clean Air Investment Fund across an interstate highway. Because the region is in to reduce reliance on cars, said Bob Wyman, partperpetual violation of ozone standards, the Clean Air ner with Latham and Watkins, a law firm in Los AnAct prohibits the Federal Highway Administration from geles, Calif. Companies would pay into the fund when approving and funding the bridge. they fall short of air quality standards. Wyman said According to lim Kutzman, EPA Region IV direc- that once protocols are developed, there will be a potor of air, pesticides, and toxics, EPA is considering tential for use of economic instruments (trading approving the development as part of its Project XL schemes). Companies could purchase air quality credprogram, which provides businesses regulatory flex- its from the fund, which would then be used to supibility in exchange for superior environmental per- port such measures as clean-fuel shuttles or public formance [ES&T, ,anuary 1198, ,p .2A). Approval transit-oriented development. Wyman said there is hinges on an analysis of how much emissions would already a similar fund, limited to ride-sharing, opbe reduced by locating the development downtown erating in the Southern California Air District. There, on existing infrastructure instead of locating it on the companies required to set up ride-sharing proinstead opt out by paying into the fund. edge of Atlanta. If the analysis is favorable, the en- grams tire project would be designated a transportation control measure, clearing the way for federal approval Reducing runoff and funding of the bridge. Unlike air quality impacts, water quality impacts of Smart growth has also grabbed high-level atten- different urban infrastructures are not dependent on tion from the Clinton Administration. The Presi- individual human behavior and choice. This has endent's Clean Water Action Plan {ES&T, Aprir l198, abled researchers to model different growth scenarp. 166A) directs EPA to develop a way to credit pol- ios and examine how each impact water quality. The lution load reductions from smart growth in the To- findings of three different studies (5,8, 9) indicate that tal Maximum Daily Load program that requires states smart-growth developments generate significantly less to clean up nonpoint sources of pollution. The plan polluted runoff. also directs the Interagency Work Group on SustainThe amount of pollution generated during rain able Communities to revise and develop policies to storms, in general, depends on the amount and losupport local smart-growth efforts that have water cation of hard or impervious surfaces (5). Rainfall quality benefits. striking a development washes pollutants, includVice President Gore announced new smart- ing nutrients and metals, off roofs, yards, streets, and growth initiatives in a speech given last September parking lots into streams and lakes. According to Tom at the Brookings Institution in Washington, D.C. The Schueler, director of the Center for Watershed Promortgage lender FANNIE MAE will launch a tection, Inc., in Ellicott City, Md., when 10% of a wa$100-million pilot program to fund mortgages on tershed surface becomes impervious, aquatic ecohomes for families with one car and access to public systems begin to degrade. A subdivision of 1- to 2-acre transit. The federal government will provide $17 mil- lots roughly corresponds to 10% impervious cover. lion to 19 states for easements to protect more than At a 25-30% impervious cover level, streams are un53,000 acres on 217 farms. In addition to reexamining able to support habitat for sensitive aquatic life (6). federal policies that encourage sprawl, the govern"In a conventional suburban development, 60% ment will also conduct a series of listening sessions of the impervious cover is devoted to habitat for cars around the country on livability and smart growth. and the remaining 40% to noncar habitat such as JAN. 1, 1999 /ENVIRONMENTAL SCIENCE S TECHNOLOGY / NEWS " 3 1 A
roofs and sidewalks," said Schueler. In addition to wide roads, the typical suburban "car habitat" also includes 10-15 parking spaces per car; noncar impervious surface averages out to half an acre per person, he noted. In smart-growth developments, imperviousness is minimized by concentrating development in areas with existing infrastructure and clustering residential development. Clustering employs open space designs with smaller housing lots, places homes close to the street to shorten driveways, increases density, reduces street widths, increases the number of homes per unit length of street, minimizes parking spaces, uses vegetated open channels for street runoff, and directs rooftop runoff to pervious areas (7). Schueler and other researchers have reasoned that, acre-for-acre, compared with contemporary sprawl developments, smart-growth developments could reduce imperviousness while providing the Scime squcire footage of homes, shops, and office This proposition has been borne out by two studies in Maryland and one in South Carolina. According to Joe Tassone, Deputy Chief of Comprehensive Planning in the Maryland Office of Planning, a detailed model of six watersheds in the Washington-Baltimore region evaluated continued sprawl growth patterns and compared them with smartgrowth development, projected over a 20-year period (see the figure on page 29). The results demonstrated that smart growth generates less nitrogen from developed areas than continued sprawl (nondirected growth) patterns (8) (see thefigureson page 30). In addition, the amount of impervious cover resulting from new development is greatly reduced, and impacts on local streams are restricted to fewer watersheds (see the figure on page 31) In a similar study of the Patuxent River basin one-quarter of the watersheds would be significantly less impervious and have better stream quality if growth were better directed than under a conventional development scenario This result, said Rich Claytor, the center's principal engineer, is consistent with a study from the Center for Watershed Protection, based in Ellicott City, Md. The center analyzed four actual developments in the Chesapeake Bay watershed, then redesigned each site on the same acreage using clustering and innovative site planning techniques. The model predicted that a medium-density residential site would have one-quarter less impervious cover and stormwater runoff than a conventional site; phosphorus output would be 60% lower; and nitrogen output would be reduced by 45% (9). A South Carolina study, managed by the Charleston Harbor Project, also developed sprawl and cluster scenarios for an actual site. The study concluded that innovatively designed cluster development released 30% less runoff and nearly 70% less nitrogen and phosphorus than conventional sprawl development (5) Making it happen Ironically, said Claytor, the innovative designs employed in his and other models would be illegal in most 3 2 A • JAN. 1, 1999 / ENVIRONMENTAL SCIENCE & TECHNOLOGY/ NEWS
jurisdictions. Most local zoning codes, he said, mandate wide streets, large housing setbacks, and separation of residential and commercial areas. In response, the Center for Watershed Protection, in conjunction with planners and local officials across the country, has developed a set of model design principles (7) and a handbook for changing local development rules (10). Stewart Meek, principal investigator at the American Planning Association in Chicago, 111., said that his organization, along with 40 others from the real estate, building, and environmental communities, have crafted model land-use statutes to reform state and regional laws {11). But, the bottom line is that "it is clear that most Americans prefer the suburbs," said Joe Molinaro, director of land development services at the National Association of Home Builders in Washington, D.C. "While there is a big resurgence in housing in central cities, not more than 5-10% of the country's housing is being built there," he said. However, asserted Ewing, "[although] the primary reason we get suburban sprawl is because developers copy a risk-free successful design, most new suburban development need not be developed in the old way." According to Ewing, "the future belongs to hybrid developments that combine traditional and contemporary design principles." He concluded that there will be more and more interest from local governments, giving the competitive edge to developers who understand smart growth. References (1) Anderson, G. Why Smart Growth, a Primer, International City/County Management Association, ICMASmart Growth Network: Washington, DC, 1998. (2) Ewing, R. Alternative views of sprawl: Is Los Angelesstyle sprawl desirable? /. Am. Planning Assoc. 1997, 63(1), 107-126. (3) Criterion, Inc.; Apogee Research, Inc. The Transportation and Environmental Impacts of Infill Versus Greenfield Developmen:: A Comparative Case Study Analysis; U.S. Environmental Protection Agency, Office of Policy, Planning, and Evaluation, Urban and Economic Development Division, U.S. Government Printing Office: Washington, DC, 1998. (4) Gordon, R; Richardson, H. W. Alternative views of sprawl: Are compact cities a desirable planning goal?/. Am. Planning Assoc. 1997, 63(1), 95-106. (5) Getting a rein on runoff: How sprawl and the traditional town compare; SCCCL Bull., 7; South Carolina Coastal Conservation League: Charleston, S.C. 1995,1-8. (6) Schueler, T. R. The importance of imperviousness. Watershed Protection Tech. 1994, 1(3), 100-111. (7) Center for Watershed Protection. Twenty-Two Model Design Principles, http://www.pipeline..om/~mrrunoff/ (accessed October 1998). (8) Maryland Office of Planning. Smart Growth Options for Maryland's Tributary Strategies; Maryland Office of Planning: Baltimore, Md., 1998. (9) Claytor, R. A. Nutrient Export from Conventional and Innovative Site Developmen,; Center for Watershed Protection: Ellicott City, Md., 1998. (10) Better Site Design: A Handbook for Changing Development Rules in Your Community. Center for Watershed Protection: Ellicott City, Md., 1998. (11) American Planning Association. Growing Smarter Legislative Guidebook, http://www.planning.org/plnginfo/ growsmar/gsindex.html (accessed October 1998).
Janet Pelleyisa contributing editorofES&T.
