United States Department of Transportation
i
Energy and Air Quality Impacts of Truck Only Lanes: A Case Study of Interstate 75 Between Macon and McDonough, Georgia
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2018-11-01
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[PDF-1.61 MB]
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Abstract:Because heavy-duty truck operations can significantly affect traffic congestion, especially on road grade, the creation of exclusive lanes for trucks has been viewed as a potential alternative to reduce congestion delay, fuel consumption, and emissions. However, few studies have rigorously evaluated the effectiveness of truck-only lanes in achieving these benefits. This study demonstrates a model framework that combines a microscopic traffic simulation with emissions and microscale dispersion models to quantify the potential impacts of truck-only lanes on fuel consumption, emissions, and near-road pollutant concentrations. As a case study, the framework was used to evaluate a proposed $2 billion project to construct 40-miles of truck-only lanes on Interstate 75 (I-75) between Atlanta and Macon, Georgia (USA). In line with expectations, vehicle simulation analyses revealed that constructing truck-only lanes had a large and positive predicted effect on enhancing both truck and general purpose lane (GPL) operations. On average, speeds are predicted to increase by 5.5% for trucks and 5.3% for GP lane traffic. Moving truck traffic off GPLs and into dedicated lanes enhances capacity for future increases in travel demand on both facilities. The enhanced vehicle operations, in turn, contributed to reducing the total vehicle-hours traveled (5.2% to 6.9% decrease, depending on traffic demand projections).The study found that the enhanced vehicle operations with the installation of the truck-only lanes helped reduce the total fuel consumption by 2.8% to 3.7%, mass emissions by 2.7% (CO2) to 8.0% (CO), and pollutant concentrations by 4.4% (NOx) to 12.8% (CO), with the magnitude of impacts varying slightly to moderately across pollutants and traffic demand projections. Reductions in pollutant concentrations are greatest near the roadway, which may be important in terms of population exposure in specific areas. In addition, the environmentally positive effects that truck-only lanes may generate are likely to increase as traffic demand continues to grow. In conclusion, the findings of this study suggest that truck-only lanes could significantly improve the traffic flow, and reduce energy, emissions, and pollutant concentrations. The research team expects that the extensive simulation results of this study help understand the performance of truck-only lanes on a large-scale network with a heavy mixture of truck and GPL traffic. The methodology and framework developed in this study can be effectively and efficiently to a wide variety of scenarios to evaluate the environmental impacts of other transportation projects under various conditions.
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