Friday, February 11, 2011

CO2 Emissions from Transportation Projects

Traffic congestion on northbound Interstate 5 ...
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Reducing Carbon Emissions from Transport Projects (107 page pdf, Asian Development Bank,  July 2010)

By the careful use of energy intensity models, this report quantified the amount of CO2 reductions that may be achieved through various scenarios or options in transportation projects, such as congestion pricing and by reductions possible from various modes, as well as the life cycle impacts of construction of infrastructure.

Key Quotes:

“expanded road capacity usually leads to long-term increases in CO2 emissions as well as local air pollution because it increases the amount of traffic.. The number of lanes has a significant impact on the total carbon footprint as it influences the demand, volume to capacity (V–C) ratios, speed, and construction emissions”

“CO2 emissions associated with construction of metro rail transit (MRT) projects with underground tracks and stations can be equivalent to those associated with several years of operations of these projects“

“Reductions in CO2 of about 20% can be obtained by techniques to mitigate congestion, manage excess speeds, and smooth traffic flow for both urban and non-urban highways”

“pollution of all types and accidents are a direct function of vehicle-km traveled, so measures that reduce traffic growth will tend to cut pollution of all types and to reduce accidents. ..CO2, particulate matter, and NOx pollution all tend to decrease as traffic speed approaches the 40–60 km per hour (kph) range, and then increase again at higher speeds “

“Braess’s paradox: adding road capacity can cause congestion..adding a new link to a transport network more often than not causes increased road congestion, rather than reduced congestion.“

“Congestion pricing of roadways can reduce CO2 emissions if applied to existing road capacity, particularly if tolls are used to support better public transportation and traffic management”

“Where applied to new road capacity, tolls and congestion pricing will tend to diminish the induced traffic that causes CO2 to increase”

“pay-as-you-drive insurance, which if universally available, can reduce CO2 by 6%–15% by ensuring that the cost of vehicle insurance is closely tied to the number of km driven, rather than priced by the year“

“Expressway projects were found to increase CO2 emissions over their 20-year lifetime ..because of effects on induced travel that overwhelm the short term benefits of curbing low-efficiency congested traffic”

“EKB analysis found that air quality impacts are highly correlated to CO2 emissions and other public health benefits, such as improved traffic safety”
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