For Heavy-duty vehicles (HDVs), the distribution of vehicle miles traveled (VMT) by vehicle type is the most significant parameters for onroad mobile source emissions modeling used in the development of air quality management and regional transportation plans. There are two approaches for the development of the HDV VMT distribution; one approach uses HDV registration data and annual mileage accumulation rates, and another uses HDV VMT counts/observations collected with the FHWA truck classification. For the purpose of emissions modeling, the FHWA truck classes are converted to those used by the MOBILE6.2 emissions rate model by using either the EPA guidance or the National Research Council conversion factors. However, both these approaches have uncertainties in the development of onroad HDV VMT distributions that can lead to large unknowns in the modeled HDV emissions. This dissertation reports a new heavy-duty vehicle visual classification and activity estimation method that minimizes uncertainties in current HDV conversion methods and the vehicle registration based HDV VMT estimation guidance. The HDV visual classification scheme called the X-scheme, which classifies HDV/truck classes by vehicle physical characteristics (the number of axles, gross vehicle weight ratings, tractor-trailer configurations, etc.) converts FHWA truck classes into EPA HDV classes without losing the original resolution of HDV/truck activity and emission characteristics. The new HDV activity estimation method using publicly available HDV activity databases minimizes uncertainties in the vehicle registration based VMT estimation method suggested by EPA. The analysis of emissions impact with the new method indicates that emissions with the EPA HDV VMT estimation guidance are underestimated by 22.9% and 25.0% for oxides of nitrogen and fine particulate matter respectively within the 20-county Atlanta metropolitan area. Because the new heavy-duty vehicle visual classification and activity estimation method has the ability to provide accurate HDV activity and emissions estimates, this method has the potential to significantly influence policymaking processes in regional air quality management and transportation planning. In addition, the ability to estimate link-specific emissions benefits Federal and local agencies in the development of project (microscale), regional (mesoscale), and national (macroscale) level air quality management and transportation plans.

Environmental indicators were developed and evaluated to assess the impact of mobile sources on emissions, air quality, exposure and health. Different levels of indicators are discussed, from single species to multipollutant indicators. Carbon monoxide (CO), Nitrogen oxides (NOx) and elemental carbon (EC) were chosen as indicators of mobile sources because emissions of these pollutants are largely attributed to mobile sources and ambient concentrations have a close response to the change in mobile source emissions. These pollutants were used in the construction of the integrated mobile source indicators (IMSI). The IMSI have larger spatial representativeness and stronger associations with cardiovascular diseases (CVD) than single pollutants. The use of IMSI in epidemiologic modeling constitutes an alternative approach to assess the health impact of pollutant mixtures and can provide support for the setting of multipollutant air quality standards. The human health benefits of reducing mobile sources emissions were more consistent using multipollutant indicators. Indicator values and uncertainties, in the form of indicator sets, are presented with their associated outcomes and attributes to be useful for policy makers who are interested not only in the value of the indicators, but also in their associated uncertainties and their applicability at other times and other regions.

Thesis (Ph.D)--Public Policy, Georgia Institute of Technology, 2009. / Committee Chair: Noonan, Douglas; Committee Member: Castillo, Marco; Committee Member: Chang, Michael; Committee Member: Cozzens, Susan; Committee Member: Rodgers, Michael. Part of the SMARTech Electronic Thesis and Dissertation Collection.

published_or_final_version / Politics and Public Administration / Master / Master of Public Administration

The United States Environmental Protection Agency has estimated that over 111 million people reside in areas that exceed the National Ambient Air Quality Standards for ozone. One major source of the chemical precursors (nitrogen dioxides and volatile organic compounds (VOCs)) for ozone are motor vehicles. The overall goal of this research is to improve the knowledge base related to VOC refueling and evaporative emissions from motor vehicles. Refueling, running loss, hot soak, and diurnal loss total and speciated VOC emissions were investigated. A total of 12 uncontrolled refueling events were completed and involved the determination of volumetric flow rates of gasoline vapor during refueling, as well as total and speciated VOC concentrations. Total VOC emissions were compared with two commonly used algorithms. Speciated VOC vapor profiles were compared with two published gasoline vapor profiles and theoretical predictions based on knowledge of liquid composition and environmental conditions. An evaluation of refueling emissions impacts on ozone formation potentials using MIR was completed and results were compared against speciated emissions and MOBILE-based total VOC emissions estimates coupled with a default speciation profile. Refueling VOC emissions and resultant ozone formation potential may be underestimated in existing emission inventories, particularly during the summer ozone season, A model was developed to predict the speciation of VOCs associated with evaporative emissions from motor vehicles. Model-predicted speciation profiles were evaluated using SHED studies. Running loss, hot soak and diurnal emissions were included in each test. Total VOC emissions measured during each test were compared against MOBILE6 predicted emissions. An evaluation of evaporative emissions impacts on ozone formation potentials using MIR was completed, comparing measured and predicted emissions. The measured:predicted speciation results ranged between 0.93 and 1.11 and had an average value of 1.02. For the conditions tested, MOBILE6 underestimated evaporative emissions in 20 of 24 comparisons. MOBILE6-based ozone formation potentials may be underestimated.

published_or_final_version / abstract / toc / Transport Policy and Planning / Master / Master of Arts in Transport Policy and Planning

High Occupancy Toll (HOT) lanes were recently proposed for I-85 in Atlanta as a way to relieve congestion and provide a reliable commute time for single occupant drivers that are willing to pay a toll. It is important to evaluate the air quality impacts of such a proposal to meet environmental regulations, such as the National Environmental Policy Act (NEPA) and Transportation Conformity Regulations. The goal of this study is to understand how vehicle mass emissions change as a result of implementing HOT lanes on I-85 in Atlanta . This is done by considering a number of factors affect mass vehicle emissions, such as vehicle activity, vehicle speeds, vehicle age distributions, and vehicle class distributions. These factors are incorporated into a base scenario, which models the current condition on I-85 with HOV lanes, and a future scenario, which models the implementation of HOT lanes on this corridor. The base scenario mainly uses data from a data collection effort by Georgia Tech during the summer of 2007 on the I-85 corridor, while the future scenario makes alterations to these data using information from other cities that have already implemented HOT lanes. The MOBILE-Matrix modeling tool, which was recently developed by Georgia Tech [16], was used to run the emissions analysis using the input factors from these data sources. This tool calculated mass emissions for five pollutants: HC, NOx, CO, PM2.5, and PM10. The results show very small increases in mass emissions for NOx, CO, PM2.5, and PM10, and very small decreases in mass emissions for HC. Therefore, the implementation of HOT lanes on I-85 in Atlanta is unlikely to violate the Transportation Conformity Rule. For NEPA purposes, this analysis could be used to make the case that air quality impacts are not significant, and therefore further detailed analyses are not required.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: See PDF for abstract. / AFRIKAANSE OPSOMMING: Sien die PDF vir die opsomming.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

When confronted with decisions involving the provision of environmental resources, such as clean air, do individuals act cooperatively with societal regulations? This study employs a quasi-experimental design to investigate the cooperative and non-cooperative actions of high-emitting vehicle owners that arose in response to the Inspection and Maintenance (IM) program in the Atlanta airshed. The impact of cooperative and non-cooperative actions of high-emitters on vehicular tail-pipe emissions, such as carbon monoxide (CO), hydrocarbons (HC) and oxides of nitrogen (NOx), is quantified. Furthermore, the hypothesis that high-emitters have significantly higher odds of residing in lower income neighborhoods as compared to the normal emitters is also tested. A remote sensing sample of approximately 1.42 million vehicles observed on-road between 1997 and 2001 is matched with IM program data and vehicle registration data to identify the cooperative and non-cooperative high-emitters. A mixed-pool time-series regression analysis is undertaken to estimate changes in vehicular tail-pipe emissions due to the actions of high-emitters. The information about the socio-economic and demographic contextual conditions of the sampled vehicle owners is ascertained from 2000 census data. Approximately 42% of the high-emitting vehicle owners are found to be cooperative and 58% non-cooperative. The cooperative actions caused a decrease of 47% in HC emission factors during 1997 and 2001. There is no statistical difference between the CO and NO emission factors of vehicles owned by cooperative and non-cooperative high-emitters. Results also suggest that the high-emitters live in 4.4% lower median household income areas as compared to the normal emitters in the Atlanta airshed. Changes in the current IM program rules and vehicle registration laws could improve air quality. Such changes include disallowing IM test failures from registering anywhere in the state of Georgia and requiring an IM test on every change of vehicle ownership inside the IM program area. Better incentive mechanisms for high-emitters can also be designed. The evidence from this study is expected to aid policy-makers to adapt the incentive mechanisms of IM programs, in particular, and environmental regulations, in general, so that public policies are both more effective and equitable in their societal impacts.