Smart Growth refers to an urban planning reform movement or philosophy that seeks to reduce environmental, fiscal, and aesthetic impacts of development by favoring more compact, mixed-use, walkable, and transit-compatible land use forms.  The term was coined in the 1990's, but its roots go back to the 1970's as roadway, utility, and water service infrastructure to meet sprawling development began to take an increasing toll on municipal budgets.

Ten commonly agreed-upon principles of smart growth are as follows [1]:

1. Provide a variety of transportation choices.
2. Mix land uses.
3. Create a range of housing opportunities and choices.
4. Create walkable neighborhoods.
5. Encourage community and stakeholder collaboration.
6. Foster distinctive, attractive communities with a strong sense of place.
7. Make development decisions predictable, fair and cost effective.
8. Preserve open space, farmland, natural beauty and critical environmental areas.
9. Strengthen and direct development towards existing communities.
10. Take advantage of compact building design and efficient infrastructure design. 

 

Smart Growth and Climate Change

Vehicle emissions make up the largest percentage of greenhouse gas emissions.  To reduce these emissions, analysts [2] have suggested a three-pronged approach will be necessary:

• Increasing the fuel efficiency of motor vehicles;
• Reducing the carbon intensity of fuels; and
  
• Reversing the growth in vehicle miles traveled .

The first two of these involve technology advances that are already achieved or well underway.  Reducing driving will be a much greater challenge since the U.S. system of planning and funding transportation systems tends to increase driving.  Research suggests that as communities are built or existing ones redeveloped, it may be possible to reduce per capita VMT of future residents, compared to what would otherwise occur.

The "Four D's"

Extensive research shows a stong link between land use/transportation design and VMT/carbon emissions.  Land use features associated with fewer auto emissions are often called the “4 D’s”:
o Density – Compactness of residential, retail, and employment uses.
o Diversity – land use mix (e.g., residential alongside retail)
o Design – Neighborhood form, including street connectivity, site design, and the pedestrian environment.
o Destinations – proximity to many destinations, i.e., how close to the region’s core.

Research findings in these four areas include as follows:

Density

Higher Density = Lower Per Capita Emissions.  As residential, retail, and/or employment density increases, decreases can be seen in per capita VMT, Vehicle Hours of Travel (VHT), the number of vehicle trips, the percent of trips by vehicles, and air emissions, including carbon.  For example, one study showed each doubling of residential density reduced VMT 32% in Chicago, 35% in Los Angeles, and 43% in San Francisco[3].

Density Is Not Enough. However, dense areas with automobile oriented designs show far less pedestrian activity and more driving[4].  Thus, density is a necessary but not sufficient condition to reduce driving and auto emissions.

Diversity (Land Use Mix)

Greater Diversity = Lower Per Capita Emissions. A Seattle study showed that increased diversity reduced VMT 19.7% and between the least diverse and most diverse categories[5].  Lumping into categories masks an even larger effect.

Design

Street Connectivity = Lower VMT.  Connectivity is a design feature that refers to the degree to which road or path system is connected, which determines the directness of walking routes.  Three studies are among several that show this relationship:

• Dense and diverse but low-walkable (i.e., poor connectivity) suburban clusters showed 1/3 the pedestrian activity of similarly dense urban areas[6].
  
•  In another study, in Seattle, a Walkability Index was calculated, based on density, street connectivity, and land use mix. The index showed that a 5% increase in walkability resulted in 6.5% lower VMT [7].
  
• A similar Walkability Index formulated for the Atlanta region showed the least walkable neighborhoods had 30% higher VMT (39 miles per capita).
  

Site Design and the Pedestrian Environment

Site design includes the quality of the walking environment, and accessibility of buildings, including locating parking in the rear rather than between the street and storefront. Three representative findings are as follows:

• A study of the Portland, Oregon, region found that if the whole region were made as pedestrian-friendly as the most pedestrian-friendly neighborhood, then regional VMT would decrease 10%[8].
• An Atanta study showed that retail density significantly predicts VMT, but is most influential at the highest density levels[9].
• Another study found that in neighborhoods where sidewalks were provided and parking was placed behind buildings, there was a significant difference in mode share (less driving, more walking, bicycling, and transit use)[10].

Destinations (Regional Location or "Centeredness")

Centeredness = Lower VMT.  Development located close to major employment, recreation, and shopping creates a large “bang for the buck” according to several studies.  In fact, many studies show regional accessibility can overwhelm all other considerations combined.  For example, a study of Bay Area (California) travel data showed that placing homes closer to employment (“jobs-housing balance”) reduced VMT 72.5% more than shifting shopping trips to alternative modes via land use mixing[11].  Therefore, outlying developments built according to New Urbanism principles are not likely to show much more emissions reduction than more conventional suburban development located closer to the urban core.

Smart Growth = 20-40% VMT Reduction

In light of the foregoing studies and many others, the most comprehensive study to date [2] concludes, that close-in, compact and walkable development “has the potential to reduce VMT per capita by anywhere from 20 to 40 percent relative to [conventional subdivisions].” This is a critical result for the effort to use smart growth as a tool against climate change.

ALSO ON THE LIVABLE STREETS NETWORK

• Streetsblog Capitol Hill:  LaHood's Twelve-Word Definition of Livability.  October 5, 2009. 

• Streetsblog Capitol Hill:  Joel Kotkin on Smart Growth:  The Streetsblog Remix.  September 18, 2009. 
• Streetsblog Network:  New Urbanism, Old Urbanism and "Creative Destruction". June 12, 2009.  
• Streetsblog Network:  Make Smart Growth Affordable By Building More of It.  October 15, 2009. 
  
• Streetsblog:  More People, Less Driving:  The Imperative of Curbing Sprawl.  September 3, 2009. 
• Streetsblog San Francisco:  Growth of Compact Development Likely, Important for Reducing VMT.  September 25, 2009. 

• Streetsblog: How Do We Make Clean Transportation Part of the National Discussion?  August 29, 2008.
  

• Streetsblog:  Orioles Pitcher Throws a High Hard One at Car Commuting. August 8, 2008.
  

REFERENCES

Each source is referred to by the same number every time it is cited. Please keep citation style consistent.

[1] Smart Growth Leadership Institute. 2007. Smart Growth Project Scorecard. Smart Growth Implementation Toolkit.

[2]  Ewing, R., Bartholomew, K., Winkelman, S., Walters, J., Chen, D. 2007. Growing Cooler: The Evidence on Urban Development and Climate Change,  Urban Land Institute.

[3] Holtzclaw, J., et al. 2002. Location efficiency: neighborhood and socio-economic characteristics determine auto ownership and use; studies in Chicago, Los Angeles and San Francisco. Transportation Planning and Technology, 25(1):1-27.

[4] Moudon, A. and P.M. Hess, 2000. Suburban clusters: the nucleation of multifamily housing in suburban areas of the Central Puget Sound Region. Journal of the American Planning Association, 66(3).

[5] Lawrence Frank and Company (LFC) Inc., et al., 2005. A study of land use, transportation, air quality and health in King County, WA. Prepared for the King County Office of Regional Transportation Planning.

[6] Hess, P. M., et al., 1999. Site design and pedestrian travel. Transportation Research Record 1674. National Research Council, Transportation Research Board. Washington, D.C. pp. 9-19.

[7] Frank L.F., et al., 2006. Multiple pathways from land use to health: Walkability associations with active transportation, body mass index, and air quality. Journal of the American Planning
Association,  72(1).

[8] Parsons, Brinkerhoff Quade and Douglas, Inc., Cambridge Systematics, Inc., and Calthorpe
Associates 1993. The Pedestrian Environment: Portland, OR: 1000 Friends of
Oregon.

[9] Levine J, and L.D. Frank 2007. Transportation and land-use preferences and residents’ neighborhood choices: The sufficiency of compact development in the Atlanta region. Transportation. 34(2):255-274.

[10] Frank, L. D., et al., 2000. Linking land use with household vehicle emissions in the central Puget Sound: Methodological framework and findings. Transportation Research D, 5(3):173–196.

[11] Cervero, R. and M. Duncan, 2006. Which reduces vehicle travel more: Jobs-housing balance
or retail-housing mixing? Journal of the American Planning Association 72(4):475 – 490.

PICTURE REFERENCES

Pictures are cited in the order they appear above. Please keep citation style consistent.

[1] Smart growth development. Photo by Dan Burden via Pedestrian Bicycle Information Center Image Library.

[2] Winter Park, FL. Photo by faceless b and EPA Smart Growth via Flickr.

[3] Pearl District redevelopment, Downtown Portland, OR. Photo by SP82454-on a break via Flickr.  

[4] Winter Park, FL, sidewalk. Photo by faceless b and EPA Smart Growth via Flickr.

[5] Vancouver, B.C., a smart growth city. Photo by ecstaticist via Flickr.

 

FURTHER READING

• Smart Growth America
  
• Smart Growth Leadership Institute
• U.S. EPA Smart Growth Home 
• Victoria Transport Policy Institute, Land Use Impacts on Transport: How Land Use Patterns Affect Travel Behavior. Updated July 22, 2008. 
• Lawrence Frank and Company, Inc. 2008. Reducing Global Warming and Air Pollution: The Role of Green Development in California, Prepared for Environmental Defense Fund.
  

 

KEYWORDS

smart growth, density, compact development, movements, New Urbanism, transit-oriented development, walkability,