Browsing by Subject "MOVES"
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Item Dynamic traffic assignment-based modeling paradigms for sustainable transportation planning and urban development(2014-05) Shah, Rohan Jayesh; Boyles, Stephen David, 1982-Transportation planning and urban development in the United States have synchronously emerged over the past few decades to encompass goals associated with sustainability, improved connectivity, complete streets and mitigation of environmental impacts. These goals have evolved in tandem with some of the relatively more traditional objectives of supply-side improvements such as infrastructure and capacity expansion. Apart from the numerous federal regulations in the US transportation sector that reassert sustainability motivations, metropolitan planning organizations and civic societies face similar concerns in their decision-making and policy implementation. However, overall transportation planning to incorporate these wide-ranging objectives requires characterization of large-scale transportation systems and traffic flow through them, which is dynamic in nature, computationally intense and a non-trivial problem. Thus, these contemporary questions lie at the interface of transportation planning, urban development and sustainability planning. They have the potential of being effectively addressed through state-of-the-art transportation modeling tools, which is the main motivation and philosophy of this thesis. From the research standpoint, some of these issues have been addressed in the past typically from the urban design, built-environment, public health and vehicle technology and mostly qualitative perspectives, but not as much from the traffic engineering and transportation systems perspective---a gap in literature which the thesis aims to fill. Specifically, it makes use of simulation-based dynamic traffic assignment (DTA) to develop modeling paradigms and integrated frameworks to seamlessly incorporate these in the transportation planning process. In addition to just incorporating them in the planning process, DTA-based paradigms are able to accommodate numerous spatial and temporal dynamics associated with system traffic, which more traditional static models are not able to. Besides, these features are critical in the context of the planning questions of this study. Specifically, systemic impacts of suburban and urban street pattern developments typically found in US cities in past decades of the 20th century have been investigated. While street connectivity and design evolution is mostly regulated through local codes and subdivision ordinances, its impacts on traffic and system congestion requires modeling and quantitative evidence which are explored in this thesis. On the environmental impact mitigation side, regional emission inventories from the traffic sector have also been quantified. Novel modeling approaches for the street connectivity-accessibility problem are proposed. An integrated framework using the Environmental Protection Agency's regulatory MOVES model has been developed, combining it with mesoscopic-level DTA simulation. Model demonstrations and applications on real and large-sized study areas reveal that different levels of connectivity and accessibility have substantial impacts on system-wide traffic---as connectivity levels reduce, traffic and congestion metrics show a gradually increasing trend. As regards emissions, incorporation of dynamic features leads to more realistic emissions inventory generation compared to default databases and modules, owing to consideration of the added dynamic features of system traffic and region-specific conditions. Inter-dependencies among these sustainability planning questions through the common linkage of traffic dynamics are also highlighted. In summary, the modeling frameworks, analyses and findings in the thesis contribute to some ongoing debates in planning studies and practice regarding ideal urban designs, provisions of sustainability and complete streets. Furthermore, the integrated emissions modeling framework, in addition to sustainability-related contributions, provides important tools to aid MPOs and state agencies in preparation of state implementation plans for demonstrating conformity to national ambient air-quality standards in their regions and counties. This is a critical condition for them to receive federal transportation funding.Item Incorporating Vehicle Emission Models into the Highway Design Process(2012-02-14) Ko, Myung-HoonAutomobile transportation consumes a significant amount of non-reusable energy and emits emissions as by-products of fuel consumption. There has been much progress in the development of vehicle engine technology and alternative fuels to reduce the adverse impact of highway transportation on the environment. However, the research regarding the reduction of the adverse impact through highway design is still in its infancy. Furthermore, highway design manuals/guidebooks do not provide any information on environmentally-friendly designs. The primary objective of this research was to provide the tools and guidelines for a quantitative environmental evaluation in highway design. This research provided the results regarding the quantitative environmental impacts, by means of fuel consumption and emissions, of various highway geometric design conditions on the vertical grades as well as for horizontal and vertical crest curves that could be included in the highway design process. The researcher generated second-by-second speed profiles using the speed prediction models and non-uniform acceleration/deceleration models, and extracted the fuel consumption and emissions rates based on vehicle specific powers and speeds using recently developed motor vehicle emission simulator (MOVES). The generated speed profiles were matched with the extracted rates and aggregated during a trip on the grades and curves. In addition, the researcher conducted the environmental evaluation including a benefit-cost analysis with actual highway geometric data based on the proposed method and processes. The results demonstrated that fuel consumption and emissions could be significantly changed according to highway design conditions on grades and curves. Throughout the analyses, this research provides the guidelines and tools for environmental evaluations related to selected design features as a part of the highway development process. The provided guidelines and tools can reduce the uncertainty associated with the engineering judgment for environmentally-conscious highway design. Finally, this research shows the efficacy of environmentally-friendly design for sustainable (i.e., social, economical, and environmental) transportation.Item Signal Timing Optimization to Improve Air Quality(2012-12-11) Lv, Jinpeng 1983-This study develops an optimization methodology for signal timing at intersections to reduce emissions based on MOVES, the latest emission model released by U.S. Environmental Protection Agency (EPA). The primary objective of this study is to bridge the gap that the research on signal optimization at intersections lags behind the development of emissions models. The methodology development includes four levels: the vehicle level, the movement level, the intersection level, and the arterial level. At the vehicle level, the emission function with respect to delay is derived for a vehicle driving through an intersection. Multiple acceleration models are evaluated, and the best one is selected in terms of emission estimations at an intersection. Piecewise functions are used to describe the relationship between emissions and intersection delay. At the movement level, emissions are modeled if the green time and red time of a movement are given. To account for randomness, the number of vehicle arrivals during a cycle is assumed to follow Poisson distributions. According to the numerical results, the relative difference of emission estimations with and without considering randomness is usually smaller than 5.0% at a typical intersection of two urban arterials. At the intersection level, an optimization problem is formulated to consider emissions at an intersection. The objective function is a linear combination of delay and emissions at an intersection, so that the tradeoff between the two could be examined with the optimization problem. In addition, a convex approximation is proposed to approximate the emission calculation; accordingly, the optimization problem can be solved more efficiently using the interior point algorithm (IPA). The case study proves that the optimization problem with this convex approximation can still find appropriate optimal signal timing plans when considering traffic emissions. At the arterial level, emissions are minimized at multiple intersections along an arterial. First, discrete models are developed to describe the bandwidth, stops, delay, and emissions at a particular intersection. Second, based on these discrete models, an optimization problem is formulated with the intersection offsets as decision variables. The simulation results indicate that the benefit of emission reduction become more and more significant as the number of intersections along the arterial increases.Item Using Local and Regional Air Quality Modeling and Source Apportionment Tools to Evaluate Vehicles and Biogenic Emission Factors(2014-07-25) Kota, Sri HCarbon Monoxide (CO), oxides of nitrogen (NO_(x)) and volatile organic compounds (VOCs) affect human health, and can also play a significant role in tropospheric ozone and secondary particulate matter formation. Correctly estimating the anthropogenic emission rates of these species is important for their effective control. Additionally, isoprene from biogenic sources also plays a key role in tropospheric ozone and secondary organic aerosol (SOA) formation. In this study, emission factors and inventories of CO, NO_(x) and VOCs from on-road vehicles estimated by vehicle emission factor models and biogenic emissions of isoprene estimated by a popular biogenic emission model are evaluated using local and regional scale air quality modeling and source apportionment tools supplemented by concentration and flux data collected at surface and in the upper air. The USEPA?s Motor Vehicle Emission Simulator (MOVES) model is evaluated. Local scale analysis indicates over-estimation of NO_(x) by approximately 15%, based on the curbside data collected near a high diesel traffic rural highway and the predicted NO_(x) by the TAMU Near-Road Model. The regional scale analysis conducted using the observed NO_(x) at a number of surface air quality monitoring sites in southeast Texas (ST) and a source-oriented Community Air Quality Model (SCMAQ), a regional chemical transport model, suggests an over-estimation of NO_(x) emissions by approximately 35-55% using the MOVES-based NEI. The near-road analysis also reveals that NO_(2)/NO_(x) ratio at curbside is approximately 29%, much higher than the generally used 5% ratio. This increase in ratio resulted in predicted 8-hour ozone increase in ST by as much as 6 ppb. While the near-road analysis didn?t reveal significant overestimation in CO emissions due to high background concentrations and low emissions, the regional analysis showed that CO emission were overestimated by approximately 60% by the MOVES model. Finally, VOC emissions estimated by the MOVES model were evaluated using fluxes of 18 VOCs measured on a tall tower in urban Houston during 2008. Vehicle contributions to the observed flux were determined using the Multilinear Engine (ME-2), a receptor-oriented source apportionment model. Emission factors of vehicle exhaust and evaporative emissions were estimated using a flux footprint model and the contributions resolved by ME-2. The MOVES model estimates vehicle exhaust emissions well, but severely under-estimates evaporative emissions from parked vehicles. The Model of Emissions of Gases and Aerosol from Nature (MEGAN) estimations of isoprene, the dominant biogenic VOC, in ST were also evaluated using SCMAQ. Comparison of predicted and observed isoprene concentrations at the surface layer and upper layers revealed a significant over-prediction of isoprene in urban areas and necessity of decreasing biogenic emission reduction by 2/3rd. The over-predictions of isoprene had negligible effects on predicted ozone concentrations in ST, but the isoprene generated SOA can be overestimated by as much as 50%.