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Greenhouse Gas Analysis
Congestion creates a concentration of idling cars
along I-5 that contribute to local and regional greenhouse gas emissions.
The primary purpose of CRC’s Greenhouse Gas Emissions (GHG) analysis was to compare
alternatives presented in the Draft EIS. The methodology used to calculate
greenhouse gas emissions was based on energy consumed during construction and
operation of the CRC project and the associated carbon dioxide that results. For
example, the combustion of diesel to power buses through the project area emits
carbon dioxide and other gases as a byproduct. Carbon dioxide is the primary
component of greenhouse gases.
A similar approach was used to study GHG emissions for the Final EIS,
with refinements to include a larger study area and the effects of bridge lifts
GHG findings in the
concluded that the “build” alternatives resulted in fewer GHG emissions than a
no build alternative. The LPA is expected to reduce regional emissions (including Washington, Clackamas, Multnomah,
and Clark Counties) by approximately 0.5 percent. At a more local level (the 12.2-mile length of I-5 surrounding the
CRC project area), the LPA is expected to reduce emissions by roughly 5.4 percent. The build alternative would carry
lower volumes of traffic due to higher transit use, a tolled bridge, and higher traffic speeds in the project area.
Opportunities exist in the future to reduce GHG emission further through:
- Improvement in system management to decrease Vehicle Mile Traveled (VMT)
- Use of lower-carbon fuels
- Vehicle efficiency
Project staff will continue to
work with both states and transportation planning agencies to improve system
management and decrease VMT.
GHG Emissions Review Panel Study affirms project analysis
During the selection process for the Locally Preferred Alternative, local partner agencies requested an
independent review of greenhouse gas emissions analysis.
In 2008, a panel of independent experts reviewed and evaluated the greenhouse
gas emissions analysis presented in the Draft EIS. The Greenhouse Gas Emissions
Expert Review Panel found the CRC analysis and conclusions to be reasonable. The
Panel agreed with the CRC finding that the Locally Preferred Alternative would
generate lower greenhouse gas emissions than the no build alternative.
Suggestions were provided to refine the calculations for the Final EIS. The
Panel’s detailed findings can be found in the
Greenhouse Gas Emission Analysis Expert
Review Panel Report.
GHG analysis receives national recognition
In 2009 the CRC Greenhouse Gas Emissions and Climate Change Evaluation was
awarded a National Environmental Excellence Award by the National Association of
Environmental Professionals, stating that the project “demonstrates a novel
method to assess the impacts of greenhouse gas emissions and through the
environmental review process identify a less overall impacting alternative for a
complex transportation project.”