The motor vehicle emission simulator (MOVES) modeling software of the U.S. Environmental Protection Agency enables researchers and practitioners to model vehicle emissions at the project level. With this tool, agencies can identify and evaluate the effectiveness of local traffic control strategies to reduce emissions at project hot spots, such as congested intersections. This study analyzes vehicle emissions at congested and uncongested signalized intersections under three traffic intersection scenarios, ranging from Level of Service (LOS) B to LOS E. Emissions are much less sensitive to congestion than control delay. A shift in operation from LOS E to LOS B reduced per vehicle nitrogen oxide emissions by 15% and particulate matter emissions by 17%, while control delay decreased by 40%. The largest sources of emissions were cruising and acceleration; they accounted for more than 80% of total emissions under all scenarios. Idling accounted for less than 18% of all intersection emissions. This analysis calculates emissions with a time-in-mode methodology that combines emission factors for each activity mode (i.e., acceleration, deceleration, cruise, idle) with a calculation of the total vehicle time spent in that mode. This approach demonstrates the contribution of each activity mode to intersection emissions and suggests opportunities for control strategies with the potential to affect intersection emissions. The streamlined methodology may be a helpful tool for agencies that are interested in analyzing project-level emissions and control strategies, but lack staff resources or expertise for microsimulation-based scenario analysis.
The most important factor for predicting DPM intake fractions for harbor activities is the proximate population density. The largest uncertainty in predicting DPM carcinogenic health risk is the carcinogenic inhalation unit risk factor.
Research sponsored by the Research and Innovative Technology Administration NATIONAL COOPERATIVE FREIGHT RESEARCH PROGRAM America's freight transportation system makes critical contributions to the nation's economy, security, and quality of life. The freight transportation system in the United States is a complex, decentralized, and dynamic network of private and public entities, involving all modes of transportation-trucking, rail, waterways, air, and pipelines. In recent years, the demand for freight transportation service has been increasing fueled by growth in international trade; however, bottlenecks or congestion points in the system are exposing the inadequacies of current infrastructure and operations to meet the growing demand for freight. Strategic operational and investment decisions by governments at all levels will be necessary to maintain freight system performance, and will in turn require sound technical guidance based on research.
Waterborne transit is one of the safest and most efficient forms of goods movement. The tug and tow industry transports more than 800 million tons of cargo each year and is a vital component of the U.S. intermodal freight transportation network. However, emissions from tugboat operations on the nation's inland river waterways and at ports affect air quality, public health, and welfare. Although ports and vessel operators can mitigate these environmental impacts with a variety of technological and operational strategies, the effectiveness and cost of each strategy vary greatly. This study analyzes the cost-effectiveness of five tugboat emission reduction strategies: (a) vessel engine repowering, (b) vessel speed reduction, (c) biodiesel, (d) diesel particulate filters, and (e) selective catalytic reduction. Each strategy is evaluated for its emissions benefits, total costs to involved parties (potentially including the tugboat industry, ports, and government agencies), and overall cost-effectiveness in reducing emissions of nitrogen oxide, carbon monoxide, particulate matter, and carbon dioxide. Application to the Ports of St. Louis, Missouri, and Houston, Texas, show that the cost-effectiveness of each strategy varies by port and depends on characteristics of the local tugboat fleet. The results of this study can be applied by public agencies and private operators when considering investments in tugboat emission reduction measures.
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