Browsing by Author "Kwon, Eil"
Now showing 1 - 20 of 25
Results Per Page
Sort Options
Item Arterial Link Travel Time Estimation Using Loop Detector Data - Phase I(Center for Transportation Studies, University of Minnesota, 1997-05) Zhang, Michael; Wu, Tong Qiang; Kwon, Eil; Sommers, Kevin; Habib, AhsanIn recognition of the need for an effective yet inexpensive way of estimating arterial travel times, MnDOT has sponsored a research project to develop a travel time estimation model using loop detector data. This project is being jointly conducted by researchers from the University of Iowa and the University of Minnesota, and will be carried out in two phases. Phase I involves a literature review, traffic data collection and development of a travel time database, and Phase II covers model development, calibration and evaluation. This report summarizes the findings of Phase I.Item Capacity Analysis for Dynamic Bottlenecks and Alternative Concepts for Coordinated Ramp Metering Operations(2001-12-01) Kwon, Eil; Nanduri, Sreemanaraya; Ambadipudi, RaviThis project involved a detailed review of coordinated metering algorithms currently operating in the United States and a simulation analysis to examine the performance of three algorithms that represent each coordination approach; the Denver incremental coordination, the Seattle Fuzzy metering, and the Minnesota explicit section-wide coordination approaches. Researchers used a macroscopic simulation model with the same geometry and traffic demand conditions. Based on the analysis results, they developed alternative metering approaches by combining conventional zone-wide control with fuzzy coordination. They also developed two new alternative procedures to estimate bottleneck capacities in real time; an adaptive estimation method using Kaman Filter and a neural-network based approach that predicts traffic volume for a given mainline location using traffic data collected from upstream and downstream detectors. Both approaches were tested with the real data collected from the sample freeway sites. The preliminary test for alternative strategies using simulation with an example freeway in Minnesota showed promising results in terms of reducing congestion and increasing throughput on the mainline. Further testing and research is recommended.Item Development and Application of Demand-Responsive Ramp Metering Control to Improve Traffic Management in Freeway Corridors(1992-01) Stephanedes, Yorgos J.; Kwon, Eil; Chang, Kaikuo; Yao, PingA method is developed for evaluating traffic-responsive ramp metering strategies and improving freeway performance. The method emulates real-time metering and rigorously traces the interactions between automatic rate-selection metering strategies and freeway performance through time. Given a demand pattern and freeway geometrics, it provides assessment of metering strategies that change continuously at very short time intervals. Further, it explicitly treats time delays that can be caused by hardware or introduced by the traffic engineer.Item Development and Application of On-Line Strategies for Intersection Control Phase I: Review of Advanced Control Strategies(Center for Transportation Studies, 1992-12) Stephanedes, Yorgos J.; Kwon, Eil; Michalopoulos, Panos G.; Mallis, John; Roetzel, RonaldSCOOT, SCATS, PRODYN and OPAC represent the state-of-the-art control strategies for signalized traffic network management by employing advanced control concept such as demand-responsive, on-line timing generation with adaptive features. While there have been individual tests of the above state-of-the-art control strategies by various agencies, no comprehensive effort has been made to evaluate and quantify the performance of each strategy, especially in terms of their applicability to both loops and video detection. This research reviews the advanced intersection control strategies developed to date. Due to the lack of field evaluation that can directly compare each control strategy, this study focused on the theoretical principles and implementation issues found from the literature. Further, the existing intersection control systems in three major cities in the U.S. and Canada are analyzed and their control algorithms are introduced. Finally, the current status of the video detection development is also reviewed.Item Development and Application of On-Line Strategies for Optimal Intersection Control (Phase III)(Minnesota Department of Transportation, 1996-10) Kwon, Eil; Stephanedes, Yorgos J.; Liu, Xiao; Chidambaram, Sabhari; Antoniades, CharalambosThe previous phases of this research reviewed and tested existing intersection control algorithms in a simulated environment. Further, a machine-vision detection system with four cameras was installed at the intersection of Franklin and Lyndale Avenues in Minneapolis, Minnesota, to develop a live intersection laboratory. Phase III enhanced the live laboratory with two additional cameras covering the intersection proper and the extended approach of southbound Lyndale Ave. A comprehensive operational plan for the laboratory was developed and a new microscopic simulator for the laboratory intersection was -also developed. Two types of new intersection control strategies, i.e., one with link-wide congestion measurements and the other based on neural-network approach, were developed and evaluated in the simulated environment. Further, using the data collected from the machine-vision detection system, an automatic procedure to estimate the intersection delay was also developed and applied to compare the performance of fixed-timing control with that of the actuated control strategy.Item Development and Application of On-Line Strategies for Optimal Intersection Control Phase II: Off-Line Evaluation of Control Strategies and Development of a Live Laboratory(Minnesota Department of Transportation, 1994-10) Stephanedes, Yorgos J.; Kwon, Eil; Liu, XiaoThis project evaluates various intersection control strategies in a simulated environment and also helped establish a live laboratory for use in future testing of new control strategies. The report reviews major intersection control strategies, including the state-of-the-art strategies with adaptive and on-line timing generation features. In addition, it details simulation results for the OPAC control strategy. The NETSIM simulator created the simulation environment for a test network that included part of downtown Minneapolis. Comparison results indicate that OPAC performs best with low-traffic demands, and pretimed control was the most effective during peak periods when traffic demand reached capacity. In conjunction with this project, Minneapolis city traffic engineers installed a machine-vision video detection system at a live intersection laboratory. Located at Franklin and Lyndale Avenues, the test site will help researchers evaluate new control strategies before full-scale implementation in later phases of this research.Item Development and Application of On-Line, Integrated Control Strategies for Optimal Metering, Incident Management and Driver Guidance in Freeway Networks: Phase I Final Report(1993-04) Stephanedes, Yorgos J.; Kwon, Eil; Chang, Kaikuo; Vairamidis, NikosManaging freeway congestion requires an integrated approach involving demand-responsive ramp metering, incident management and driver guidance. While a freeway network acts as a system, i.e., conditions on any part affect other parts in the network, the state of the art in real-time freeway management has not reached the point where comprehensive, network-wide optimal control schemes are automatically generated and implemented through on-line optimization and coordination of various control actions. A major difficulty lies in the lack of efficient computational algorithms implementable for on-line optimization, and the lack of accurate on-line predictors, that can predict traffic demand and diversion in freeway networks. As a result of the above limitations, most traffic responsive metering systems, such as the Twin Cities freeway control system, employ automatic rate-selection procedures. These procedures select the most appropriate metering rates for a ramp from a pre-determined library using the information received from loop detectors on the main freeway, upstream and downstream from the ramp. Although this method provides a degree of self-adjustment to prevailing traffic conditions, the lack of an efficient analysis tool to evaluate and update the key components of the control, i.e., thresholds and rate-libraries, significantly restricts the effectiveness of control.Item Development of a Guideline for Work Zone Diversion Rate and Capacity Reduction(Minnesota Department of Transportation, 2016-03) Kwon, Eil; Park, ChongmyungThis study develops a comprehensive guideline to estimate the traffic diversion rates and capacity reduction for work zones. The analysis of the traffic diversion patterns with data from past work zones in the metro freeway network in Minnesota resulted in a set of the diversion-estimation models that relate the diversion rates at freeway ramps with the travel times and speed levels on a freeway and alternative routes during construction. The interrelationship between diversion and work-zone traffic conditions has led to the development of an iterative process, where a freeway simulation model interacts with the diversion-estimation models until a convergence is achieved between diversion and resulting freeway delays. Freeval is adopted in this study as the simulation tool for freeways. The test results of the iterative process with the work zone data showed promising results in determining both the diversion rates and freeway delay for a given work-zone. Due to the types of the work zones used in developing the diversion models, the iterative process developed in this study can be applicable to only "two-to-one" lane reduction cases in estimating the diversion rates for the mainline exit flows, while the diversion rates at entrance ramps can be determined without such restrictions. The capacity analysis of the lane-closure sections performed in this study has also resulted in a set of the suggested capacity values for the work zones with two-to- one lane reduction.Item Development of a Parallel Simulation Algorithm for Freeway Traffic Flows on a Distributed Personal Computer System: Final Report for Phase I(Intelligent Transportation Systems Institute, Center for Transportation Studies, University of Minnesota, 1997-12) Kwon, EilThis research investigates the feasibility of developing low-cost, personal computer-based parallel processing procedures that can be applicable to real time simulation of freeway flows. Specific objectives include, * Development of a framework for PC-based parallel simulation system * Enhancements of existing freeway traffic models for parallel simulation * Development of a PC-based, parallel simulation algorithm for freeway flows. * Development of a prototype version of a PC-based parallel simulation system Performance evaluation of the PC-based parallel freeway simulation system.Item Development of a Road Condition Recovery Time Estimation System for Winter Snow Events(Minnesota Department of Transportation, 2018-01) Kwon, Eil; Park, ChongmyungThis research develops a Normal Condition Regain Time (NCRT) estimation system, which automatically determines the NCRT at detector stations on the metro-freeway network for given snow events. The NCRT process is based on the findings that the speed level during the recovery process reaches a stable free-flow-speed (FFS), whose value is generally lower than the pre-snow FFS at a same location. Further, the speed-density (U-K) relationship of the traffic flow after snow is cleared exhibits a similar but shifted-down pattern of the normal-day U-K relationship at a given location. In this study, the after-snow traffic condition with a stable but shifted-sown pattern of the normal-day U-K relationship is defined as the āwet-normalā condition, and the NCRT is defined as the time when the U-K data during a snow event starts to follow the wet-normal U-K pattern at a given station. The NCRT estimation system first collects the traffic and weather data for the metro-freeway network and determines the normal-day U-K relationships for the detector stations whose traffic data include both uncongested and congested regions. The normal-day U-K relationships are then applied to calibrate the wet-normal U-K patterns at given locations using the traffic data collected during snow events. Finally, the NCRTs are determined for each station by comparing the U-K data trajectory during a given event with the wet-normal U-K pattern at given locations. The NCRT estimation system has been applied to a set of the sample snow events.Item Development of a Travel-Time Reliability Measurement System(Minnesota Department of Transportation, 2018-09) Kwon, Eil; Park, ChongmyungThis study has developed a computerized Travel-Time Reliability Measurement System (TTRMS), which can automate the time-consuming process of gathering and managing data from multiple sources and calculating various types of reliability measures under user-specified conditions for given corridors. The TTRMS adopts a server and client structure, where the main database and computational engines reside in the server, while the user- clients are designed for entering the data and generating the output files. In particular, most of the external data, such as traffic and weather datasets, can be remotely downloaded following predefined time schedules. Further, the travel-time calculation process developed in this study can explicitly reflect various lane-configurations at work zones for correctly calculating travel times of the routes with work zones. The map-based user interfaces provide users with a flexible environment, where the route selection and specification of operating conditions for reliability estimation can be efficiently performed. The integrated TTRMS was tested in the Twin Citiesā metro freeway network by estimating the reliability measures of selected corridors with real data for a two-year period, 2012-13. The test results indicate that the TTRMS can substantially reduce the time and effort in estimating various types of reliability measures under different operating conditions for predefined corridors.Item Development of Active Traffic Management Strategies for Minnesota Freeway Corridors(Minnesota Department of Transportation, 2015-06) Kwon, Eil; Park, ChongmyungIn this study, the effectiveness of the I-35W variable advisory speed limit system on the improvement of the traffic flow was evaluated with the real traffic data. The analysis results indicate there was significant reduction in the average maximum deceleration and also the traffic time reliability was substantially improved during a peak hour period. Based on the assessment results, an enhanced version was developed to be able to reflect more effectively the time-variant road traffic conditions in determining the variable speed limits in real time. The coordinated adaptive metering strategy, developed in the previous phase of this research, is also enhanced and implemented in the field in this research. The field test results of the new metering system with the 100 NB corridor indicate substantial improvements in both the mainline and ramp traffic performance compared with those from the old stratified algorithm.Item Development of an Integrated Simulation Package for Freeway Design, Operations and Adaptive Traffic Management. Phase I: Enhancement of the Kronos Simulation Program(1992-01) Michalopoulos, Panos; Kwon, Eil; Lee, Chifung; Mahadevan, Gopalakrishnan; Kang, JeongGyuThe main purpose of this project is to make KRONOS, a microcomputer-based freeway simulation program under development operational by resolving the following problems problems: detailed field testing and adjustments of the program with real freeway data, analysis of sensitivities in simulation models with respect to the variations in input data, and enhancements of the input/output module to be suitable for the Mn/DOT planning environment. In addition, a new simulation module to treat special types of freeway segements incluing merging/diverging of two freeways is developed and incorporated into KRONOS in this project. The major accomplisments made in this project are summarized.Item Development of Freeway Operational Strategies with IRIS-in-Loop Simulation(Minnesota Department of Transportation, 2012-01) Kwon, Eil; Park, ChongmyungThis research produced several important tools that are essential in managing and operating freeway corridors. First, a computer-based off-line process was developed to automatically estimate a set of traffic measures for a given freeway corridor using the historical detector data. Secondly, a prototype on-line estimation procedure was designed to calculate selected traffic measures in real time to assist operators in identifying abnormal traffic patterns. Third, the IRIS-in-loop simulation system was developed by linking IRIS, the freeway control system developed by MnDOT, to a microscopic simulation software through a data communication module, so that new operational strategies can be directly coded into IRIS and evaluated under the realistic simulation environment. Finally, two new freeway operational strategies, variable speed limit control and a density-based adaptive ramp metering strategy, were developed and evaluated with the IRSI-in-Loop simulation system.Item Development of Signal Operations Research Laboratory for Testing and Development of Advanced Control Strategies, Phase 1(2002-07-01) Kwon, Eil; Kim, Sangho; Kim, Dongsoo; Lee, EnhaA virtual intersection environment consisting of a new microscopic traffic simulator and a 2070 traffic controller was developed to provide a platform for a realistic pseudo real-time evaluation of intersection control strategies. The new simulator is based on an object-oriented modeling approach. In particular, the interface between the simulator and the traffic controller was developed using a commonly available digital input/output card and the Windows NT registry. Further, a signal converter was also developed to transform the format of the emulated detector data from the simulation model into the data format acceptable by the traffic controller. The implementation of the intersection control strategies into the 2070 controller was performed using the field I/O manager module provided by the City of Los Angeles DOT. The resulting Hardware-in-loop simulation system was applied to evaluate different control strategies for an intersection, i.e., pre-timed, actuated and adaptive methods.Item Development of Traffic Simulation Laboratory For Design Planning and Traffic Operations (Phase I)(Center for Transportation Studies, University of Minnesota, 1996-12) Michalopoulos, Panos; Sommers, Kevin; Reynhout, Kenneth; Kota, Ramesh; Kwon, EilThe key element in improving traffic operations and performing effective real time management is the ability to assess the effectiveness of the various alternatives prior to implementation. Simulation methods have long been recognized as the most effective tool for such an analysis, and various simulators have been developed by different agencies for freeway and arterial networks. While there have been individual tests of each software by various agencies, no comprehensive effort has been made to quantify and evaluate the performance of each model. The major difficulty includes the lack of detailed real data and the time-consuming manual effort to prepare input information for each software. To be sure there is no user-interface developed to data that can generate input files for different simulators with a common set of data. Recent installation of the state-of-the art video detection systems in the 1-394 freeway provides a unique opportunity to develop a comprehensive freeway database that can be used to create various test cases with detailed traffic database that can be used to create various test cases with detailed traffic information. Further, the 1-494 Integrated Corridor Traffic Management project being conducted by MN/DOT will be able to provide valuable corridor traffic data which can be used for evaluating freeway/arterial network models. By evaluating existing traffic simulation models the advantages/disadvantages of each model can be identified. Based on the evaluation results a comprehensive modeling approach for freeway/arterial networks can be developed. The ultimate goal of this research is to develop a traffic simulation laboratory where various roadway design/operational alternatives can be evaluated with traffic simulators under an integrated database-simulation environment. The proposed research, Phase I, will evaluate existing freeway simulation models with detailed traffic data to be collected using machine-vision an loop detection systems.Item Dynamic Estimation of Freeway Weaving Capacity for Traffic Management and Operations, Phase II(2003-07-01) Kwon, EilAn adaptive procedure is presented to estimate the time-variant capacity at consecutive weaving areas in real time. The proposed procedure uses the volume/occupancy data commonly available from single loop detectors and estimates the maximum total volume that can enter a given freeway weaving segment through time. The behavior at several weaving sites with consecutive weaving segments were analyzed, using loop and video data as well as visual observation. The online identification process with a Kalman Filter reduces estimation errors by continuously updating the parameters of the underlying models with the most recently measured data. The test results with real data show that the proposed procedure can estimate the upper limit values of the mainline flow approaching given weaving segments with reasonable accuracy. This procedure addresses the effects of entrance ramp flows, which can be controlled through ramp metering, on the maximum possible mainline volume approaching weave areas. The procedure may be directly applicable in improving ramp metering operations, and in the development of better design of freeway weaving segments.Item Energy Conservation Through Improvement of Freeway Operation: Development of a Prototype Integrated Simulation/Database Package(1993-09) Kwon, Eil; Michalopoulos, Panos; Lee, Chifung; Xie, Hui; Tong, SaiThe main objective of this research is to develop a prototype version of an integrated simulation/database package. The specific objectives include: 1) Development of a framework for an integrated simulation/database package, 2) Development of a prototype version of a graphical freeway traffic database management system, 3) Enhancement of freeway traffic flow models for various geometric types, 4) Preliminary study to develop an optimal calibration procedure for simulation parameters.Item Enhancements of the Kronos Simulation Package and Database for Geometric Design Planning, Operations and Traffic Management in Freeway Networks/Corridors (Phase II)(Minnesota Department of Transportation, 1994-12) Kwon, Eil; Michalopoulos, Panos; Xie, Hui; Tong, SaiThis report summarizes the enhancement results of the KRONOS freeway traffic simulation package. KRONOS is a personal computer-based, dynamic freeway simulation software, which is based on the continuum flow modeling approach. Unlike other macroscopic simulation programs, KRONOS explicitly models interrupted flow behavior such as merging, diverging, and weaving. The resulting KRONOS version, v8.0, which operates under the MS-DOSĀ® environment, can simulate two freeways merging/diverging with a common section for a total length up to 20 miles with eight lanes. The new multi-stage incident module can handle up to six capacity-variant stages, which allows evaluation of various management strategies. A spread-sheet formatted output file stores the simulated results of traffic parameters, such as flow, speed, and density. Separate output files also store the measures of effectiveness, such as delay and total travel time. The current version takes approximately three minutes to simulate a 20-mile section for one hour on an IBM-PC compatible with the Pentium-90 MHZ processor.Item Enhancements of the Kronos Simulation Package and Database for Geometric Design Planning, Operations and Traffic Management in Freeway Networks/Corridors (Phase III)(Minnesota Department of Transportation, 1997-07) Kwon, Eil; Kota, Ramesh; Coyle, Michael; Michalopoulos, Panos; Song, SejunThis report summarizes the final results of the research effort to develop a freeway traffic simulator with the capability to evaluate freeway operational strategies, such as traffic-responsive ramp metering and high-occupancy vehicles (HOV) lanes. Researchers first developed an efficient software data structure by adopting a dynamic memory allocation scheme to use the available memory as efficiently as possible. That work also included modifying the existing macroscopic, segment-based modeling structure and developing new types of pipeline segments to facilitate detection modeling and further model enhancements. Based on the new segment-based modeling structure, researchers developed a new simulation module to handle HOV lane traffic flows and extended the simulation procedure for an exclusive HOV lane to handle a network of freeways. Further, the simulation model also incorporates a new module to emulate the traffic-responsive ramp metering algorithm implemented by the Traffic Management Center since the 1980s. The new software structure developed in this research allows the future addition of new metering algorithms without major difficulties. To facilitate the data input process for the expanded simulation features, a new Windows-based user interface was developed using the Delphi software development tool kit. With the new user interface, most of the data input process can be done without exiting the main menu screen.