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

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
� 4.6 Infrastructure Construction and Maintenance
The energy used in the construction and maintenance of highway infrastructure, and the
corresponding GHG emissions, are significant. One recent study estimated that
infrastructure contributes up to 17 percent of total life-cycle transportation GHG
emissions, with about two-thirds of these related to road construction (Chester, 2008).
However, most of these emissions are attributed to other sectors, especially the industrial
sector (construction and materials production), and therefore are not part of the
transportation emissions inventory referenced in Section 2.0 of this report. A recent EPA
study estimated that the highway, street, and bridge construction subsector is responsible
for 17.6 mmt CO2e annually, representing 13.2 percent of all construction sector emissions.
Materials production and transport, as well as transportation agency facilities and
operations, contribute additional GHG emissions.
Techniques are available to reduce the amount of energy consumed and GHG emitted in
the construction, maintenance, and operations of transportation infrastructure. Some of
these involve production techniques for materials (such as asphalt and concrete) that are
most extensively used in highways, but also are used for other modes. Others involve
reductions in energy use and GHG emissions associated with the construction and
operating practices of transportation agencies, including highway departments, transit
agencies, railroads, and port and airport authorities.
Construction Materials
Definition
Greenhouse gas emissions from
infrastructure construction and
maintenance activities can be
reduced through the use of less
energy-intensive construction
materials by State and local highway
departments and other transportation
agencies. Most roadways, as well as
airport runways, are built out of
either concrete (made from Portland
cement) or asphalt (blacktop).
Greenhouse gas reduction strategies
are available for both of these major
materials:
Construction Materials
Benefits: Low: 18 mmt CO2e in 2030
Direct Costs: Unknown; probably low for fly-ash concrete
Net Included Costs: Unknown
Confidence in Estimates: High
Key Co-Benefits and Impacts: Positive
• Recycling of material; reduced exposure to air
pollutants
Feasibility: High
• Initiatives in progress
Key Policy Options:
• Continued research and development on warm-mix
asphalt
• Construction material requirements/ standards
• The Portland cement production
process produces a large amount of GHGs due to the large amount of fuel needed to
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