Spatial Technologies-GIS and Smart Growth30 Sep, 2006 By: James L. Sipes
Smart growth, using GIS, seeks to improve planning.
Traffic sucks! There—I said it—and I dare anyone who has driven through Atlanta's rush-hour traffic in the past year or so to disagree with me. Atlanta was ranked the 16th most congested city in the United States in 1992, but today it has the worst congestion in the nation. The fundamental problem is that Atlanta's suburbs are built around the automobile. Virtually every trip—to work, school, restaurants, recreation—involves climbing in a car and driving to where we need to go.
Unfortunately, the situation in Atlanta is becoming commonplace throughout the country. According to a study by the U.S. House of Representatives, the average annual delay per person more than tripled in the past decade or so, and all indications are that this problem will get worse as communities continue to grow. According to the U.S. Census Bureau, population is projected to increase from 281 million in 2000 to 338 million in 2025 to 404 million in 2050. Communities are struggling to find ways to accommodate future growth while meeting environmental goals and reducing dependence on cars.
Many are turning to a process called smart growth, which seeks to help us make better decisions about how we plan the places where we live. GIS is an effective tool for implementing smart growth because it provides the tools needed to analyze and manage the massive amounts of information needed to make better decisions about how we build communities.
In This Article
At its core, smart growth is all about walkable neighborhoods, a variety of housing opportunities and choices, mixed land uses, preservation of open space, higher densities, interconnected networks of streets, outstanding architecture and the integration of art, recreation and wellness into our communities. In many ways, it advocates a return to the time before World War II, when we designed communities built around people, not automobiles. This approach to development often is called New Urbanism.
One of the major reasons that so many communities are considering smart growth principles is that suburban sprawl has gotten out of hand. Atlanta, for example, increased its population by 60% but increased its urbanized land by 80%, adding 571,000 acres between 1982 and 1997. Nashville had a similar problem. The metropolitan population of the city grew by 289,000 between 1982 and 1997—a 33% increase. However, the amount of urbanized land increased by 216,000 acres—a rise of more than 100%. According to EPA (U.S. Environmental Protection Agency), the solution to this growth discrepancy is to increase densities in areas that are best suited to handle it, while preserving agricultural land and open space in the other areas. This type of suitability analysis is what GIS does best.
Smart Growth Planning with GIS
One of the real keys to smart growth is to develop plans that fit the land. Planners use geospatial data as the foundation for all design and planning decisions. By identifying buildable areas, as well as areas to protect, we can generate an opportunities-and-constraints map that guides future decisions. For example, the cost of development increases considerably on slopes steeper than 30%, and the potential negative environmental impacts from erosion and surface runoff go up significantly as well. The best solution would be to restrict building development to land with slopes less than 30%.
A site analysis exploring the percent buildable area is essential when considering an alternative development approach such as a conservation subdivision. In most parts of the country, a conservation development must have a minimum of 40% open space with the other 60% encompassing the roads, infrastructure and lots.
The traditional urban grid has short blocks, straight streets and a crosshatched pattern. The typical contemporary suburban street network has large blocks, curving streets and a branching pattern. Traditional grids disperse traffic rather than concentrating it at a handful of intersections, and they offer more direct routes. They encourage walking and biking with their direct routing and their alternatives to travel along high-volume streets. Using some type of grid pattern is the best way to increase density because lots can be small and follow a regular pattern. Grid patterns are not effective for areas with steep slopes, so a site-selection process looking for slopes less than 10% can help identify areas that are most suitable for higher-density development.
The compactness of land use and the organization of the transportation system determines, to a large extent, how far individuals drive. The further the places we live are from those where we work and play, the more miles and hours individuals must travel to get from one place to another. One of the objectives of smart growth is to create walkable communities. GIS is effective at mapping pedestrian zones and determining walking distances to and from significant features. GIS also can be used to develop routing studies to determine how people get from one place to another. A transportation system with several different options helps reduce congestion points that create bottlenecks.
Many communities are asking how they can accommodate growth while still protecting their water resources. Development that uses land efficiently and protects natural lands can allow a community to grow and still protect its water resources. There is sufficient GIS data available for virtually every watershed in the continental United States to determine water resource issues such as stormwater runoff and nonpoint pollution.
A common misconception is that low-density development will best protect water resources, but many water-quality experts say that isn't the case. According to a study by EPA, higher densities may better protect water quality, especially at the lot and watershed levels. EPA used geospatial data to compare the stormwater runoff from different development densities. It found developments that use compact development forms, provide a mix of uses and efficiently use existing infrastructure are more effective at preserving critical environmental areas such as streams and wetland areas.
NPS (nonpoint source pollution) is a major contributor to water-quality problems. With GIS, we can map the effects of NPS and then explore alternative scenarios for minimizing impact.
One way that communities implement smart growth principles is by developing systems that rank and analyze different development alternatives. Various organizations and several municipalities have developed scorecards that help communities assess their policies and proposed development projects. The EPA's Development, Community and Environment division collects scorecards and rating systems from across the country and makes the information available on its Web site, but doesn't necessarily endorse them.
Two examples of smart growth scorecards are the EarthCraft Communities and LEED-ND guidelines. EarthCraft Communities is a certification program that helps land developers identify and implement positive environmental practices. Some issues that these guidelines address include suburban sprawl, water quality and conservation, multimodal transportation, energy and materials consumption and community education.
The U.S. Green Building Council, the Congress for the New Urbanism and the Natural Resources Defense Council have been working together to develop LEED-ND (LEED for Neighborhood Development). LEED-ND is a rating system for neighborhood location and design based on the combined principles of smart growth, urbanism and green building. LEED-ND is guided by the Charter for New Urbanism and the Smart Growth Network's ten principles of smart growth, which instruct planners to:
- 1. mix land uses;
- 2. take advantage of compact building design;
- 3. create housing opportunities and choices for a range of household types, family sizes and incomes;
- 4. create walkable neighborhoods;
- 5. foster distinctive, attractive communities with a strong sense of place;
- 6. preserve open space, farmland, natural beauty, historic buildings and critical environmental areas;
- 7. reinvest in and strengthen existing communities and achieve more balanced regional development;
- 8. provide a variety of transportation choices;
- 9. make development decisions predictable, fair, and cost-effective; and
- 10. encourage citizen and stakeholder participation in development decisions.
Among these issues, other principles will be addressed such as density, proximity to transit, mixed use, mixed housing type and pedestrian- and bicycle-friendly design.
Preliminary guidelines have been established for LEED-ND, and the final program is expected to be finalized in 2008. The current draft of the LEED-ND rating system is expected to be revised significantly before it is used for the LEED-ND pilot program.
Both EarthCraft and LEED-ND using a ranking system to determine how well a design and planning project meets smart growth principles. The LEED-ND ranking system, for example, has 100 possible points. A score of 80 would earn a platinum rating, 60 points a gold rating, 50 points a silver rating, and 40 points, certification. Many of the items in these types of scorecards are best evaluated using GIS because it helps quantify information.
Building Better Communities
With access to critical geospatial data, we can avoid the problems of the past, when we had to make educated guesses. By using GIS to foster smart growth, we can make better decisions and build better communities that use resources efficiently.
James L. Sipes is a senior associate with EDAW in Atlanta, Georgia, and the founding principal of Sand County Studios in Seattle, Washington. Reach him at firstname.lastname@example.org.