Greenhouse Gas and Urban Congestion: Incorporating Carbon Dioxide (CO_2) Emissions and Associated Fuel Consumption into TTI’s Urban Mobility Report

摘要

TTI’s Urban Mobility Report (UMR) (1) is acknowledged as the most authoritative source ofinformation about traffic congestion and its possible solutions. As policymakers from the localto national levels devise strategies to reduce greenhouse gas (GHG) emissions, the level ofinterest in the environmental impact of urban congestion has increased. To this end, researchersdeveloped and applied a methodology to determine carbon dioxide (CO_2) emissions due tocongestion for inclusion in the UMR. The methodology also estimated fuel consumption basedupon the carbon dioxide emissions estimates.Researchers developed a five-step methodology using data from three primary datasources: 1) the Federal Highway Administration’s (FHWA’s) Highway Performance MonitoringSystem (HPMS), 2) INRIX traffic speed data, and 3) The United States EnvironmentalProtection Agency’s (EPA) MOtor Vehicle Emission Simulator (MOVES) model. Emissionrates (lbs. of CO_2 per mile) were validated in selected cities, with results in the range of 80percent to 99 percent of selected emission inventories.Researchers incorporated the new methodology for all urban areas into the 2012 UrbanMobility Report and plan to include these same measures in future releases of the report.Researchers reported that, in 2011, 56 billion pounds of additional CO_2 were produced in all 498urban areas during congestion only, equating to 2.9 billion gallons of “wasted” fuel. Researchersreported the amount of CO_2 produced at free-flow conditions (i.e., absent congestion) is 1.8trillion pounds in 2011 in all 498 urban areas.