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DRIVING AND THE BUILT ENVIRONMENT: THE EFFECTS OF

COMPACT DEVELOPMENT ON MOTORIZED TRAVEL, ENERGY USE,

AND CO2 EMISSIONSSeptember 1, 2009

Transportation Research BoardDivision on Engineering and Physical Sciences

Of the National Research Council

Andy Cotugno, MetroCongress for New Urbanism

Transportation SummitNovember 4-6, 2009

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STUDY CHARGE and SCOPE

Charge: To examine the relationship between land development patterns and motor vehicle travel in the U.S. and assess whether petroleum use and CO2 emissions could be reduced by changes in development design.

Focus: Metropolitan areas and personal travel

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Committee on the Relationships Among Development Patterns, Vehicle Miles Traveled, and Energy Consumption

José A. Gómez-Ibáñez, Chair, Harvard University, Cambridge, MassachusettsMarlon G. Boarnet, University of California, IrvineDianne R. Brake, PlanSmart NJ, TrentonRobert B. Cervero, University of California, BerkeleyAndrew Cotugno, Metro, Portland, OregonAnthony Downs, The Brookings Institution, Washington, D.C.Susan Hanson, Clark University, Worcester, MassachusettsKara M. Kockelman, The University of Texas at AustinPatricia L. Mokhtarian, University of California, DavisRolf J. Pendall, Cornell University, Ithaca, New YorkDanilo J. Santini, Argonne National Laboratory, Argonne, IllinoisFrank Southworth, Oak Ridge National Laboratory, Tennessee, and Georgia Institute of Technology, Atlanta

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KEY CONCEPTS

COMPACT, MIXED-USE DEVELOPMENT: Land use patterns that increase the density, mix of uses, contiguity, connectedness, and pedestrian orientation of development

Location matters – high residential density in the middle of nowhere yields few benefits

Compact, mixed-use development ≠ multifamily housing only– small-lot, single-family development can yield benefits

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FINDINGS

Finding 1: More compact development patterns are likely to reduce VMT.

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FINDINGS (cont’d)

Finding 2: The most reliable studies estimate that doubling residential density across a metropolitan area might lower household VMT by about 5 to 12 percent, and perhaps by as much as 25 percent, if coupled with higher employment concentrations, significant public transit improvements, mixed uses, and other supportive demand management measures.

FINDINGS (cont’d)

Double Density = 5-12% Design = add 3% Diversity (land use mix) = add 5% Density+Diversity+Design = 13% Population Centrality = 15% All Built Environment Variables = 25%

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FINDINGS (cont’d)

Finding 3: More compact, mixed-use development can produce reductions in energy consumption and CO2 emissions both directly and indirectly.

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FINDINGS (cont’d)

Finding 4: Significant increases in more compact, mixed-use development result in only modest short-term reductions in energy consumption and CO2 emissions, but these reductions will grow over time.

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SCENARIO ASSUMPTIONSBASE CASE SCENARIO 1 SCENARIO 2

New & replacement hsg units (millions)

2030: 46-572050: 62-105

Same as base Same as base

Density of new development

Same as current 25% is twice as dense

75% is twice as dense

VMT per household

Current(21,187 mi/yr)

12 % lessIf twice as dense

25% lessIf twice as dense

Fuel/VMT New car 35 mpg (28 mpg on road) by 2020, improving slowly thereafter

Same as base Same as base

CO2/Fuel Current Same as base Same as base

Current Density New Density1.66 DU/acre 0.99 DU/acre

2.89 DU/acre 1.93 DU/acre

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SCENARIO ASSUMPTIONS

Sources: National Resources Inventory (US Dept. of Ag.) and US Census

1970 Suburban Population = 54.5%2000 Suburban Population = 62%

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Finding 4 (cont’d)

Bottom Line Estimate: Reduction in VMT, Energy Use, and CO2 emissions from more compact, mixed-use development in the range of <1 % to 11 % by 2050.

Committee disagreed about plausibility of extent of compact development and policies needed to achieve high end estimates.

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FINDINGS (cont’d)

Finding 5: Promoting more compact, mixed use development on a large scale will require overcoming numerous obstacles:

Local zoning, engineering and parking codes, housing preference

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FINDINGS (cont’d)

Finding 6: Changes in development patterns entail other benefits and costs that have not been quantified in this study:

infrastructure costs, social equity, health, neighborhood revitalization, transit feasibility, housing choice and price, farm land and wildlife habitat preservation

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RECOMMENDATIONS

Recommendation 1: Policies that support more compact, mixed-use development and reinforce its ability to reduce VMT, energy use, and CO2 emissions should be encouraged.

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RECOMMENDATIONS (cont’d)

Recommendation 2: More carefully designed studies of the effects of land use patterns and the form and location of more compact, mixed-use development on VMT, energy use, and CO2 emissions are needed to implement compact development more effectively.

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HOW TO ACCESS THE REPORT

Report, report summary, and commissioned papers are available

athttp://www.TRB.org/Publications/Public/Blurbs/162093.aspx

QUESTIONS?Andy.Cotugno@oregonmetro.gov