Assessing Different Freeway Interchange Design Impacts On Traffic Emission And Fuel Consumption Through Microsimulation.

Date of Award


Degree Name

M.S. in Civil and Environmental Engineering and Engineering Mechanics


Department of Civil and Environmental Engineering and Engineering Mechanics


Deogratias Eustace


The environmental impact attributed to vehicular emissions at interchanges and other roadway designs should be considered as significant as their traffic safety and operational performances. In today's world, we all are aware of the importance of climate change and global warming. As freight and passenger travel demands increase, so do congestion and emissions from the transportation sector, especially on-road vehicles, which have drawn significant attention in recent years. With an estimated 29% contribution to the total U.S. greenhouse gas (GHG) emissions by economic sectors, transportation is the highest contributor to GHGs in the nation. PTV Vissim emission calculator provides an opportunity for us to perform a comparative emissions analysis. This thesis involves a case study of an existing service interchange, a conventional diamond interchange (CDI) at Austin Blvd on I-75 located about 12 miles south of downtown Dayton Ohio, with other two alternative designs, a diverging diamond interchange (DDI) and a single-point urban interchange (SPUI), in terms of fuel consumptions, emissions, and traffic operations for similar traffic conditions, and roadway characteristics through microsimulation. In this research study, we focused on carbon dioxide (CO2) and two other critical pollutant gases emitted from vehicles' exhaust pipes, carbon monoxide (C.O.) and nitrogen oxides (NOx), including fuel consumption. The signal optimization for each interchange was conducted utilizing PTV Vistro and traffic simulation and emissions analysis using PTV Vissim. The results indicate that the existing CDI design results in much higher emission rates than the other two alternative designs, the SPUI and the DDI, for each traffic level condition considered. A reduction of 85% on average in emissions rates and fuel consumption for both alternative designs compared to the existing CDI was observed. Although the SPUI's and DDI's performances were very close, some significant difference was observed at high traffic volume and high left-turning traffic volumes. The emissions at the DDI design were lower compared to the SPUI design.


Freeway Interchange, Vehicle Emissions, Vissim Microsimulation, Fuel Consumption, Vistro Modeling, Calibration

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