Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
alternative to new development on far-flung “greenfields,” is another component of this
strategy that has been demonstrated to reduce vehicle-travel through shorter trip lengths
and better access to travel alternatives.
Although land use policies are typically under local authority, regional, State, and Federal
agencies can support regional growth objectives through funding policies, fiscal
incentives, and technical assistance to local agencies. Some recent examples are described
in the sidebar on page 5-53. Additional Federal leverage could be provided through
strategies such as:
• Establishing Federal transportation funding programs targeted at land use planning
and/or supportive implementation strategies that meet particular objectives (e.g.,
pedestrian improvements in compact, mixed-use development areas);
• Changing U.S. DOT Statewide and metropolitan planning regulations to require
greater consideration of land use (e.g., the development of regional transportation and
land use scenarios in long-range planning);
• Expanding technical assistance programs such as EPA’s Smart Growth
Implementation Assistance program;
• Including “smart growth” criteria in evaluating candidates for grant or loan programs
related to transportation, housing, economic development, etc.;
• Providing additional funds, or other incentives such as grant criteria, specifically for
brownfields cleanup and redevelopment; and
• Making Federal transportation funding at least partially based on performance or
incentive criteria for regional and local achievement of land use planning or
implementation objectives.
Magnitude and Timing of GHG Reductions
The impacts of land use patterns at a site or neighborhood level can be significant. A
recent review of the literature concluded that vehicle-travel was reduced by approximately
20 to 40 percent for residents of “compact” neighborhoods compared to residents of
“sprawl” neighborhoods (Ewing et al., 2007). Infill sites have been shown to reduce VMT
by 15 to 50 percent compared to greenfields locations (CCAP, no date). However, the net
benefits with respect to GHG reduction are tempered by the long-term nature of land use
changes. Land use change can occur as population in a region grows, and as obsolete
building stock is replaced. Nelson (2006) estimates that 6 percent of the U.S. housing stock
and 20 percent of the commercial building stock is torn down and rebuilt, each decade.
Figure 5.5 shows the impacts of population density (as well as other factors) on carbon
emissions per household – households in high-density neighborhoods produce about half
the annual CO2 emissions as those in the lowest-density neighborhoods.
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