Browsing by Subject "Intelligent transportation systems"
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Item Autonomous intersection management(2009-12) Dresner, Kurt Mauro; Stone, Peter, 1971-; Porter, Bruce W.; Waller, S T.; Kuipers, Benjamin J.; Veloso, Manuela M.Artificial intelligence research is ushering in an era of sophisticated, mass-market transportation technology. While computers can fly a passenger jet better than a human pilot, people still face the dangerous yet tedious task of driving. Intelligent Transportation Systems (ITS) is the field focused on integrating information technology with vehicles and transportation infrastructure. Recent advances in ITS point to a future in which vehicles handle the vast majority of the driving task. Once autonomous vehicles become popular, interactions amongst multiple vehicles will be possible. Current methods of vehicle coordination will be outdated. The bottleneck for efficiency will no longer be drivers, but the mechanism by which those drivers' actions are coordinated. Current methods for controlling traffic cannot exploit the superior capabilities of autonomous vehicles. This thesis describes a novel approach to managing autonomous vehicles at intersections that decreases the amount of time vehicles spend waiting. Drivers and intersections in this mechanism are treated as autonomous agents in a multiagent system. In this system, agents use a new approach built around a detailed communication protocol, which is also a contribution of the thesis. In simulation, I demonstrate that this mechanism can significantly outperform current intersection control technology-traffic signals and stop signs. This thesis makes several contributions beyond the mechanism and protocol. First, it contains a distributed, peer-to-peer version of the protocol for low-traffic intersections. Without any requirement of specialized infrastructure at the intersection, such a system would be inexpensive and easy to deploy at intersections which do not currently require a traffic signal. Second, it presents an analysis of the mechanism's safety, including ways to mitigate some failure modes. Third, it describes a custom simulator, written for this work, which will be made publicly available following the publication of the thesis. Fourth, it explains how the mechanism is "backward-compatible" so that human drivers can use it alongside autonomous vehicles. Fifth, it explores the implications of using the mechanism at multiple proximal intersections. The mechanism, along with all available modes of operation, is implemented and tested in simulation, and I present experimental results that strongly attest to the efficacy of this approach.Item Intelligent transportation systems(2011-08) Locke, Danielle Marie; Engineering Management; Darwin, Thomas Jason, 1966-; Nichols, Steven Parks, 1950-Many transportation systems used today are costly, slow, fragmented, and dangerous. This paper explores the inefficiencies and negative impacts associated with our current transportation systems. Simple to technologically advanced solutions are explored along with how to integrate these methods for all users in a sustainable fashion. The vision proposes a blend of scientific method, technological advancement, and common sense which is environmentally aware and integrated for all users by using the Dutch Regional and Sustainable Traffic Management Process.Item A microsimulation analysis of the mobility impacts of intersection ramp metering(2013-12) Wall, William Jared; Walton, C. MichaelUrban freeway demand that frequently exceeds capacity has caused many agencies to consider many options to reduce congestion. A series of solutions that falls under the Active Traffic Management (ATM) banner have shown promising potential. Perhaps the most popular ATM strategy is ramp metering. Ramp metering involves limiting the access of vehicles to freeways at an entrance ramp. By doing this, freeway throughput, speeds, and travel time reliability can be increased, while the number of traffic incidents can be decreased. This study examines the application of an innovative ramp metering strategy, Intersection Ramp Metering (IRM), at a section of Loop 1 in Austin, TX. IRM implements the ramp metering function at the intersection immediately upstream of the entrance ramp, rather than on the ramp itself. A microsimulation analysis of this application is performed in VISSIM, and the results confirm that freeway throughput (+10%), and system average travel time (-14%), can be improved, as well as several other performance measures.Item Stochastic dynamic traffic assignment for intermodal transportation networks with consistent information supply strategies(2001-08) Abdelghany, Khaled Faissal Said, 1970-; Mahmassani, Hani S.Private car use continues to increase in most urban areas around the world, exacerbating various associated problems such as traffic congestion, environmental degradation and high fuel consumption. With the dispersion of land-use activity patterns in many urban areas, serious challenges face the design of public transportation systems to provide an effective substitute for the private car. A more plausible approach would be to design and promote an intelligent intermodal transportation system, which integrates the private car with existing or planned transit modes. Several Intelligent Transportation Systems (ITS) capabilities and user services, which fall in the areas typically referred to as Advanced Travelers Information Systems (ATIS), Advanced Traffic Management Systems (ATMS), and Advanced Public Transportation Systems (APTS), offer promising opportunities to manage traffic and improve operation in intermodal networks. Providing real-time information to users on network congestion, and availability and status of transit modes, could contribute to efficient integration among the existing modes, and hence to more efficient trips for travelers. This research develops a stochastic dynamic trip assignment model for urban intermodal networks. The model overcomes limitations of static tools used in current practice. These limitations relate to the type of alternative measures that may be evaluated, and the policy questions that planning agencies are increasingly asked to address. The model captures the interaction between mode choice and dynamic assignment under different information provision strategies and network control schemes. A simulation-based solution algorithm is presented for the problem. The model incorporates a stochastic network loading model for intermodal networks and a multi-objective shortest path algorithm. The algorithm solves for the time-dependent flows for each feasible mode-path combination in the network. This research also addresses the design of real-time consistent-normative information supply strategies for the auto travelers in the network. Providing travelers with real-time information could help them plan their trips efficiently and achieve better spatial-temporal network traffic distribution. The problem is formulated as a bilevel mathematical program where the main objective is to minimize the total travel time in the network, while the secondary objective is to minimize the difference between the provided information and experienced travel times.