Browsing by Author "Dr. George F. List, Committee Member"

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    Sustainable Service Rate Analysis at Signalized Intersections with Short Left Turn Pockets Using Macroscopic Simulation
    (2010-04-20) Reynolds, William Leonard; Dr. Billy M. Williams, Committee Co-Chair; Dr. Nagui M. Rouphail, Committee Chair; Dr. George F. List, Committee Member
    A macroscopic simulation tool is developed and tested in order to quantify the effects of short turn pockets on the sustainable service rate of a signalized intersection. Unlike the theoretical signal capacity, the sustainable service rate includes queue interaction effects and is thus influenced by blockage and spillback at the entrance to a short turn pocket. Previous research on the topic has focused either on the probability of spillback from a short turn pocket or the operation of a system with a single approach lane. No macroscopic model currently available has the ability to analyze throughput reductions due to short turn pocket effects on a multilane approach. The model described herein utilizes a series of flow and density restrictions on cells of varying sizes on the approach to the intersection. Results indicate sensitivity of the model to turn pocket spillback, blockage, saturation flow rate, pocket length, lane utilization, phase sequence, phase overlap, permitted phasing, and time-dependent demand. A phase optimization procedure is also described to help efficiently allocate green time for a given set of turn pocket lengths and turn movement percentages. Outputs from the model compare favorably to results generated using microsimulation software, and recommendations are made regarding additional model enhancements and testing needs.
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    U.S. International Container Trade: Trends, Air Quality Effects, and Best Practices for Mitigation
    (2009-04-23) Keilson, David Paul; Dr. John R. Stone, Committee Member; Dr. Billy M. Williams, Committee Chair; Dr. George F. List, Committee Member
    The purpose of the paper is to identify relationships between international trade and air quality, and to identify principles and practices to mitigate the air quality impacts of trade growth. The focus is on container trade. The primary modes examined are trucking, rail, and marine. After a brief background on the magnitude of U.S. international container trade, the paper identifies trends in international and domestic container transportation. Freight contributions to national and regional emissions are described. Air quality at major gateways and hubs is examined. Current and proposed emission and fuel standards are discussed and compared across modes. Projections of future freight emissions and modal contributions are discussed. Principles are described to guide the evaluation of mitigation practices. A list of practices is compiled for each mode, including technology, operational, institutional, and infrastructure approaches. Recommendations are given for mitigation strategies and for further research.