Browsing by Author "Liao, Chen-fu"

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    Analysis of a Differential Global Positioning System as a Sensor for Vehicle Guidance
    (Minnesota Department of Transportation, 1996-09) Bodor, Robert; Alexander, Lee; Liao, Chen-fu; Bajikar, Sundeep; Morellas, Vassilios; Donath, Max
    An ongoing research project examines guidance systems, which can take over control of a vehicle if the driver becomes incapacitated. Part of this project includes an evaluation of a Differential Global Positioning System (DGPS) for vehicle-based lane sensing. This report documents the results of tests of the 5 Hz NovAtel RT20 DGPS receiver. A series of 32 static tests found the overall mean and standard deviation for the offset errors within specifications. In a series of dynamic tests, in which the vehicle was driven around the track at speeds of 20-35 miles per hour, after removing the effect of the GPS receiver's latency, the DGPS determined position exhibited a mean offset error of -17.3 cm (-6.82 in) and a mean standard deviation of 25.5 cm (10.1 in) in the direction of vehicle motion. In the direction perpendicular to vehicle motion, the mean offset was 4.57 cm (1.8 in) with a mean standard deviation of 39.6 cm (15.6 in). With no overhead obstructions in these tests, continuous satellite lock was possible. Tests at higher speeds based on a more accurate methodology are planned for the future.
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    Development of Mobile Accessible Pedestrian Signals (MAPS) for Blind Pedestrians at Signalized Intersections
    (Center for Transportation Studies, 2011-06) Liao, Chen-fu; Rakauskas, Michael; Rayankula, Avanish
    People with vision impairment have different perception and spatial cognition as compared to the sighted people. Blind pedestrians primarily rely on auditory, olfactory, or tactile feedback to determine spatial location and find their way. They generally have difficulty crossing intersections due to lack of traffic information at intersections. Among the intersection crossing sub-tasks, locating crosswalk, determining when to cross and maintaining alignment to crosswalk while crossing are the most difficult tasks for the blind and visually impaired. To understand how the blind pedestrians make safe crossing decisions, ten blind and low-vision individuals were interviewed. The purpose of these interviews was to understand the types of information they use while making safe intersection crossings and identify new information types that could assist them. A Mobile Accessible Pedestrian Signals (MAPS) prototype was developed to support decision making at signalized intersections. The MAPS integrates sensors on a Smartphone, Wi-Fi, and Bluetooth technologies, and traffic signal controllers were developed to provide intersection geometry information and Signal Phasing and Timing (SPaT) to pedestrians who are blind at signalized intersections. A single-tap command on the Smartphone screen allows users to request for intersection geometry information, such as street name, direction and number of lanes at a corner of an intersection. A double-tap input while pointing toward desired direction of crossing will confirm the crossing direction, request for pedestrian phase, and the Smartphone application will then wirelessly request for signal timing and phasing information from traffic signal controller.
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    Engaging Undergraduate Students in Transportation Studies through Simulating Transportation for Realistic Engineering Education and Training (STREET).
    (Transportation Research Board, 2009) Liao, Chen-fu; Liu, Henry; Levinson, David M
    The practice of transportation engineering and planning has evolved substantially over the past several decades. A new paradigm for transportation engineering education is required to better engage students and deliver knowledge. Simulation tools have been used by transportation professionals to evaluate and analyze the potential impact of design or control strategy changes. Conveying complex transportation concepts can be effectively achieved by exploring them through simulation. Simulation is particularly valuable in transportation education because most transportation policies and strategies in the real world take years to implement with a prohibitively high cost. Transportation simulation allows learners to apply different control strategies in a risk-free environment and to expose themselves to transportation engineering methodologies that are currently in practice. Despite the advantages, simulation, however, has not been widely adopted in the education of transportation engineering. Using simulation in undergraduate transportation courses is sporadic and reported efforts have been focused on the upper-level technical elective courses. A suite of web-based simulation modules was developed and incorporated in the undergraduate transportation courses at University of Minnesota. The STREET (Simulating Transportation for Realistic Engineering Education and Training) research project was recently awarded by NSF (National Science Foundation) to develop web-based simulation modules to improve instruction in transportation engineering courses and evaluate their effectiveness. Our ultimate goal is to become the epicenter for developing simulation-based teaching materials, an active textbook, which offers an interactive learning environment to undergraduate students. With the hand-on nature of simulation, we hope to improve student understanding of critical concepts in transportation engineering and student motivation toward transportation engineering, and improve student retention in the field. We also would like to disseminate the results and teaching materials to other colleges to integrate the simulation modules in their curricula.
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    Freight Performance Measure Systems (FPMS) System Evaluation and Data Analysis
    (University of Minnesota Center for Transportation Studies, 2008-01) Liao, Chen-fu
    One of the key measures of freight performance along interstate corridors in the United States is the average speed of travel. This report documents the findings and analysis of the ATRI Freight Performance Measure (FPM) database systems and investigates a potential FPM system design that can efficiently and effectively processes more and larger Automatic Vehicle Location (AVL) datasets collected from various trucking companies. The current FPM system at ATRI was evolved from its previous system based on GIS software. The averaged speed calculations resulting from the data process of each FPM system are somewhat different. Analysis of the average speed calculation and investigation of speed differences are discussed in chapter one. FPM database system analysis and comparison are included in chapter two. The final chapter presents an ideal FPM system and requirements needed for migration.
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    ROAD: An Interactive Geometric Design Tool for Transportation Education and Training
    (American Society of Civil Engineers, 2013) Liao, Chen-fu; Levinson, David M
    Traditionally, students use pencil and ruler to lay out lines and curves over contour maps for roadway geometry design. Numerous calculations of stopping sight distance, minimum turning radius, and curve alignments are required during the roadway design process in order to ensure safety, to minimize economic and environmental impacts, as well as to reduce construction costs. Iterative computations during the design process are usually performed manually by the students in order to meet any given design criteria and environmental constraints. The traditional design process of roadway geometry design is often cumbersome and time consuming. It limits students from taking a broader perspective on the overall roadway design process. An Internet-based roadway design tool (ROAD: Roadway Online Application for Design) was developed to enhance the learning experience for transportation engineering students. This tool allows students to efficiently design and to easily modify the roadway design with given economic and environmental parameters. A 3D roadway geometry model can be generated by the software at final design to allow students immerse themselves in the driver's seat and drive through the designed roadway at maximum design speed. This roadway geometry design tool was deployed and tested in a civil engineering undergraduate class in spring 2006 at University of Minnesota, Department of Civil Engineering. Feedback was collected from instructors and students that will lead to additional enhancements of the roadway design software.