Browsing by Author "Michalopoulos, Panos"

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Access to Destinations: Twin Cities Metro-wide Traffic Micro-simulation Feasibility Investigation
(Minnesota Department of Transportation, 2008-05) Hourdos, John; Michalopoulos, Panos
The economic importance of effective traffic management becomes more and more evident as traffic demands increase. Faced with the negative effects of traffic congestion including higher transport costs, greater energy consumption, and increased driver delays, transportation agencies around the world areas have responded by building new roads and enhancing their traffic management systems. However, the high costs associated with these projects, and the possibility that improvements in different parts of a complex traffic management system may give rise to unforeseen interactions, have prompted many metropolitan areas to invest in the creation of metro-wide simulation systems that support the evaluation of alternative traffic management scenarios across an entire traffic network. Such undertakings are far from simple; even small-scale microscopic simulations require large amounts of high-quality data. The objectives of this project were to evaluate the feasibility of developing a traffic simulation system for the Minneapolis-St. Paul metropolitan area, and to propose the most appropriate methodology for the design and implementation of such a system, taking into account local needs and capabilities.
Accident Prevention Based on Automatic Detection of Accident Prone Traffic Conditions: Phase I
(University of Minnesota Center for Transportation Studies, 2008-09) Hourdos, John; Garg, Vishnu; Michalopoulos, Panos
Growing concern over traffic safety as well as rising congestion costs have been recently redirecting research effort from the traditional crash detection and clearance reactive traffic management towards online, proactive crash prevention solutions. In this project such a solution, specifically for high crash areas, is explored by identifying the most relevant real time traffic metrics and incorporating them in a crash likelihood estimation model. Unlike earlier attempts, this one is based on a unique detection and surveillance infrastructure deployed on the freeway section experiencing the highest crash rate in the state of Minnesota. This state-of-the-art infrastructure allowed video recording of 110 live crashes, crash related traffic events, as well as contributing factors while simultaneously measuring traffic variables such as individual vehicle speeds and headways over each lane in several places inside the study area. This crash rich database was combined with visual observations and analyzed extensively to identify the most relevant real-time traffic measurements for detecting crash prone conditions and develop an online crash prone conditions model. This model successfully established a relationship between fast evolving real time traffic conditions and the likelihood of a crash. Testing was performed in real time during 10 days not previously used in the model development, under varying weather and traffic conditions.
Activation of the I-394 Laboratory for ITS Operational Testing: Phase 2
(Center for Transportation Studies, University of Minnesota, 1998-04) Reynhout, Kenneth; Michalopoulos, Panos; Siagian, Alexander
The key element in improving traffic operations and performing real-time management is the ability to assess the effectiveness of various alternatives prior to implementation. Likewise, the crucial feature for providing this capability is a Traffic Data Management System (TDMS), which gathers data and makes it available for various traffic analysis applications. The purpose of this research is to develop TDMS as part of a Laboratory Environment for TRaffic ANalysis (LETRAN). Such a laboratory environment would provide easy and efficient access to various kinds of traffic data for use in simulation, control, incident detection, and other types of traffic analysis applications to be deployed in a next-generation traffic management center. In addition, a Machine-Vision Laboratory (MVL) will be designed and implemented as part of the Center for Transportation Studies(CTS) Intelligent Transportation Systems Laboratory (ITS Lab). This MVL will use live video feeds from both freeways and arterial streets and provide machine-vision technology for conducting traffic detection, data collection, and group training exercises. Such capabilities will allow for the collection of detailed, accurate, and continuous data for successful model development, calibration, testing and evaluation.
Activation of the I-394 Laboratory for ITS Operational Testing: Phase I
(Center for Transportation Studies, University of Minnesota, 1997-12) Reynhout, Kenneth; Michalopoulos, Panos; Sullivan, Mike; Siagian, Alexander
This and other related research have two primary objectives: 1. To develop practical operational tools which can be deployed for use in traffic-management and transportation planning activities. 2. To develop a laboratory infrastructure which will facilitate future advances in traffic modeling and other ITS initiatives. The objectives of this particular research project are as follows: * A thorough examination and documentation of the 1-394 system's specifications. * Diagnosis of the working condition of the 1-394 system. * Negotiation and implementation of a repair plan * Establishing a communications connection between the ITS Lab and the Traffic Management Center (TMC). * Activation of the 1-394 Lab, which will include a user's guide that describes the steps a user should take to access video, make a connection to the TMC and the 1-394 system, and configure the system for traffic detection and data collection. A completed 1-394 Lab would be a unique and valuable tool for obtaining information that loop-detectors have been unable to supply. This information includes flow dynamics, incident behavior, capacity, and other traffic-flow characteristics. This information is vital for fine tuning operational tools and schemes to be deployed in a future TMC, and will also provide an information foundation for future research and development.
Adaptive Cruise Control System Design And Its Impact on Traffic Flow
(Center for Transportation Studies, University of Minnesota, 2005-05-01) Rajamani, Rajesh; Levinson, David M.; Michalopoulos, Panos; Wang, J.; Santhanakrishnan, Kumaragovindhan; Zhu, Xi
This study resolves the controversy over the stability of constant time-gap policy for highway traffic flow. Previous studies left doubt as to the effectiveness of constant time-gap policies and whether they maintain stability in all traffic conditions. The results of this study prove that the constant timegap policy is in fact stable to a limit. At this limit, depending on the boundary conditions, conditions lose their stability. This study develops alternative ways to maintain the balance between safety and traffic flow for ACC vehicles that does not rely on constant time-gap policies. New spacing policies will create more stability, and therefore safer conditions, and allow for greater traffic capacity.
Advanced Portable Wireless Measurement and Observation Station
(2005-07) Hourdakis, John; Morris, Ted; Michalopoulos, Panos; Wood, Kyle
The authors of this project designed, assembled, and deployed a temporary detection and surveillance system to collect real-time data on traffic conditions. This information is critical in construction, Advanced Traffic Management Systems, Advanced Traffic Information Systems, and other design and operational activities. Because traditional, permanent systems collect data by sensors in the pavement and transmit it through land-based communications, this equipment is subject to failure in construction areas. Through advancements in wireless technology, the developed system integrates machine vision sensors to collect data, compress digital video for surveillance, and use wireless nommunications for information retrieval and remote control. This new system can be added to current installations or used to create temporary traffic monitoring systems.
Development of Advanced Traffic Flow Models and Implementation in Parallel Processing: Final Report
(1992-10) Lyrintzis, Anastasios; Michalopoulos, Panos; Chronopoulos, Anthony
Advanced traffic management and control schemes require that traffic simulation models be adequately accurate and computationally efficient in describing traffic flow dynamics. It is proved by practice that the continuum models are more suitable for such purposes. The KRONOS model, developed at the University of Minnesota for traffic flow simulations, is based on a simple continuum formulation implemented by a finite difference method. The results show that the program can be used for transportation planning, design, maintenance operations and freeway management. The main purpose of this project, funded by the Center for Transportation Studies of the University of Minnesota, is to reduce the above flaws by developing advanced traffic flow models. Moreover, various numerical methods are investigated in this project.
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, JeongGyu
The 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.
Development of Real-Time Traffic Adaptive Crash Reduction Measures for the Westbound I-94/35W Commons Section
(University of Minnesota Center for Transportation Studies, 2008-12) Hourdos, John; Xin, Wuping; Michalopoulos, Panos
Much research has been conducted in the development, implementation, and evaluation of innovative ITS technologies aiming to improve traffic operations and driving safety. An earlier project succeeded in supporting the hypothesis that certain traffic conditions are favorable to crashes and in developing real-time algorithms for the estimation of crash probability from detector measurements. Following this accomplishment a natural question is “how can this help prevent crashes?” This project has the ambitious plan of not only answering this question but also providing a multifaceted approach that can offer different types of solutions to an agency aimed at reducing crashes in this and other similar locations. This project has two major objectives; first it aimed at utilizing a cutting edge 3D virtual reality system to design and visualize different driver warning systems specifically for the I-94 westbound high crash location in Minneapolis, MN. Second, in view of the desire of local engineers for a more traditional approach, this project explored the use of existing micro-simulation models in the evaluation of safety improvements for the aforementioned high crash area. This report describes the results of these investigations but more importantly describes the lessons learned in the process of the research. These lessons are important because they highlight gaps of technology and knowledge that hampered this and other research projects with similar objectives.
Development of the Next Generation Stratified Ramp Metering Algorithm Based on Freeway Density
(Center for Transportation Studies, 2011-03) Geroliminis, Nikolas; Srivastava, Anupam; Michalopoulos, Panos
A new coordinated, traffic-responsive ramp metering algorithm has been designed for Minnesota’s freeways based on density measurements, rather than flows. This is motivated in view of recent research indicating that the critical value of density at which capacity is observed is less sensitive and more stable than the value of capacity, thereby resulting in m ore effective control. Firstly, we develop a methodology to estimate densities with space and time based on data from loop detectors. The methodology is based on solving a flow conservation differential equation (using LWR theory) with intermediate (internal) freeway mainline boundaries, which is fast er and more accurate from previous resear ch using only external boundaries. To capture the capacity drop phenomenon into the first-order model we utilize a fundamental diagram with two values of capacity and we provide a memory-based methodology to choose the appropriate value in the numerical solution of the problem. Secondly, with respect to ramp metering, the main goals of the algorithm are to delay the onset of the breakdown and to accelerate system recovery when ramp metering is unable due to the violation of maximum allowable ramp waiting time. The effectiveness of the new control strategy is being assessed by comparison with the currently deployed version of the Stratified Zone Algorithm (SZM) through microscopic simulation of a real 12-mile, 17 ramp freeway section. Simulations show a decrease in the delays of mainline and ramp traffic, an improvement 8% in the overall delays and avoidance of the maximum ramp delay violations.
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, Eil
The 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.
Development of Traffic Simulation Laboratory for Design Planning and Traffic Operations (Phase II)
(2000-06-01) Telega, Paul; Michalopoulos, Panos
A key element in improving traffic operations and performing effective real-time traffic management is using simulation to assess the effectiveness of various alternatives prior to implementation. The research conducted here is Phase II of a three phased project with the ultimate goal of creating and running traffic simulation experiments in real-time. In the first phase, a set of well-known freeway simulators was evaluated. Major difficulties were a lack of real data, and the time consuming effort required to prepare data for each simulator. Phase I found that developing an integrated traffic analysis environment, where data processing, simulation and output analysis can be automated as efficiently as possible was of critical importance in improving traffic management and operations. In the second phase, the development of an Automated Simulations Tool (AST) was of critical importance. Phase II was partitioned into four major tasks: development of a Geometry Data Container (GDC), Creation of a partial Twin Cities Freeway Geometry, development of an AST, and specification of a real-time AST framework. Each part of this phase was essentially prescribed by the Phase I results. The GDC would be the design and implementation of a common geometry database that could be shared among different simulators. Initially, only a micro simulator would be implemented, but later other simulators could be added. Creation of a partial Twin Cities Freeway Geometry would be the base level common geometry that is entered. All the detail needed for a micro simulation is entered including freeway sections, detector locations and types, ramp meters, and other fine VII details. This work needs to be done only once with our design. Any subnetwork of the original entered network can be selected with a mouse and saved as a new network. Development of the AST will allow traffic engineers to select a freeway and a time period for simulation and then essentially run a simulation without any direct manipulation of data. Traffic engineers will not need to know anything about the data formats of either geometry or flow data in order to run a simulation. Finally, from what we have learned in Phase II we can specify what needs to be done for a real-time implementation of the AST: Phase III. By real-time we mean using the detector data as soon as it is available from Mn/DOT for simulation.
Employment of the Traffic Management Lab for the Evaluation and Improvement of Stratified Metering Algorithm - Phase III
(Minnesota Department of Transportation, Research Services Section, 2007-05) Liu, Henry; Wu, Xinkai; Michalopoulos, Panos; Hourdos, John
The evaluation results (done in Phase II) demonstrated that the SZM strategy was generally beneficial. However, they also revealed that freeway performance degraded by reducing the ramp delays. Therefore, it is desired to improve the effectiveness of the current SZM control. There are two objectives in this study. One objective is to improve the control logic of current SZM strategy. This is accomplished through an estimation algorithm for the refined minimum release rate. The simulation results indicate that the improved SZM strategy is very effective in postponing and decreasing freeway congestion while resulting in smoother freeway traffic flow compared to the SZM strategy. The second objective of this project is to improve the current queue size estimation. Depending on the counting error of queue and passage detectors, freeway ramps are classified into three different categories, and different methods are applied respectively for improved queue size estimation. The surveillance video data were recorded and used to verify the improvement of the proposed methods. The results indicate that the proposed methods can greatly improve the accuracy of queue size estimation compared with the current methodology. Also, the proposed method was evaluated by the micro-simulation. The simulation results indicate the performance of freeway mainline is significantly improved. And the total system performance is better than the original SZM control.
Employment of the Traffic Management Lab for the Evaluation and Improvement of Stratified Metering Algorithm - Phase IV
(Minnesota Department of Transportation, 2007-12) Liu, Henry; Wu, Xinkai; Michalopoulos, Panos; Hourdos, John
Freeway ramp control has been successfully implemented since mid 60's, as an efficient and viable freeway management strategy. However, the effectiveness of any ramp control strategy is largely dependent on optimum parameter values which are preferably determined prior to deployment. This is certainly the case happening to the current Stratified Zone Metering (SZM) strategy deployed in the 260 miles freeway network of Minneapolis - St. Paul metropolitan area. In order to improve the performance of the SZM, which highly depends on the values of more than 20 parameters, this research first proposed a general methodology for site-specific performance optimization of ramp control strategies using a microscopic simulation environment, as an alternative to trial and error field experimentation, and implemented the methodology to the SZM. The testing results show that the new SZM control with site-specific optimum parameter values significantly improves the performance of freeway system compared with the original SZM strategy. Secondly, this research proposed a methodology to explore the common optimum parameter values for the current SZM strategy for the whole Twin Cities freeway system, in order to replace the site-specific optimum values which have minor practical value because of the difficulties in implementation and numerous time-consumption to search the site-specific optimum values for all the freeway sections. The common parameter values are identified applying the Response Surface Methodology (RSM) based on 4 specifically selected freeway sections which can represent all types of freeway sections in Minneapolis-St. Paul metropolitan area.
Employment of the Traffic Management Laboratory (TRAMLAB) for Evaluating Ramp Control Strategies in the Twin Cities
(2002-06-01) Michalopoulos, Panos; Hourdakis, John; Muralidhar, K A; Sekhar, A; Subramaniam, V K
Ramp metering is one way to address freeway traffic congestion. This study employs the Traffic Management Laboratory (TRAMLAB) to evaluate the effectiveness of Mn/DOT's control strategy in three Twin Cities freeway sections totaling approximately 65 miles. It develops a new traffic management concept for early detection of incident-prone traffic conditions and integrates it in order to smooth flow and prevent incident occurrence, thereby further reducing delays and improving safety. The project is part of a larger program which aims to develop the TRAMLAB as part of the ITS Laboratory at the University of Minnesota. Such an environment will contain state-of-the-art traffic simulation programs and allow the development of viable, intelligent, and automated traffic-flow simulation programs and simulation systems that can function as both operational and research tools. Keywords-traffic simulation, traffic control, corridor control, ramp metering, accident prevention, machine, vision detector, freeway
Employment of the Traffic Management Laboratory (TRAMLAB) for Evaluating Ramp Control Strategies in the Twin Cities - Summary
(2002-06-01) Michalopoulos, Panos; Hourdakis, John; Muralidhar, K A; Sekhar, A; Subramaniam, V K
As freeway traffic congestion spreads ramp metering is implemented to address the problem. However, recently there is increasing opposition to freeway ramp control caused by excessive ramp delays. The objective of this research is to employ a recently developed tool called Traffic Management Laboratory (TRAMLAB) for assessing the effectiveness of Mn/DOT's control strategy in three Twin Cities freeway sections totaling approximately 65 miles. The feasibility of a corridor simulation will be followed by the selection and preliminary model development of the combination of an arterial and a freeway in the Twin Cities. As a result of this testing, TRAMLAB will evolve into an effective tool for developing control strategies that could reduce ramp delays without excessively increasing freeway congestion. Finally, a new traffic management concept for early detection of incident prone traffic conditions will be developed and integrated to traffic management through Ramp Metering and Variable Message Signs in order to smooth flow and prevent (to the extend possible) incident occurrence, thereby further reducing delays and improving safety. Even though this proposal focuses on evaluating ramp metering and implementing a concept recently developed in a current project, we also address the more general issue of research continuity and suggest a strategic partnership with MnDOT. Keywords-Traffic Simulation, Traffic Control, Corridor Control, Ramp Metering, Accident Prevention, Machine, Vision Detector, Freeway
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, Sai
The 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.
Energy Conservation Through Video Imaging and On Line Traffic Monitoring: Final Report
(1993-06) Michalopoulos, Panos; Pettersson, Ake
This report describes a 'fully automated', simple and practical approach for extracting (in real time) sufficiently accurate measurements of the most common traffic parameters and Measures of Effectiveness (MOE) such as volumes, speeds, stops, delays, queue lengths, travel times and Level of Service, at intersections and highway segments. Then, those estimates are used to compute reasonable estimates of fuel consumption and pollution levels such as nitrous oxide, hydrocarbons and carbon monoxide emissions. To collect the necessary real time vehicle detection data required by the MOE algorithms, a machine vision system called Autoscope is utilized. This report presents and proposes the use of the Autoscope and its accompanying Autoscope vehicle detection and MOE data collection programs as a viable option for real time traffic monitoring and analysis of intersections and highway segments.
Enhanced Micro-Simulation Models for Accurate Safety Assessment of Traffic Management ITS Solutions
(University of Minnesota Center for Transportation Studies, 2008-11) Xin, Wuping; Hourdos, John; Michalopoulos, Panos
Much research has been conducted in the development, implementation, and evaluation of innovative ITS technologies aiming to improve traffic operations and driving safety. Existing micro-simulation modeling only describes normative car-following behaviors devoid of weakness and risks associated with real-life everyday driving. This research aims to develop a new behavioral car-following model that is pertinent to the true nature of everyday human driving. Unlike traditional car-following models that deliberately prohibit vehicle collisions, this new model builds upon multi-disciplinary findings explicitly taking into account perceptual thresholds, judgment errors, anisotropy of reaction times and driver inattention, in order to replicate “less-than-perfect” driving behavior with all its weakness and risks. Most importantly, all parameters of this model have direct physical meaning; this ensures vehicle collisions are replicated as a result of behavioral patterns rather than simply being numerical artifacts of the model. Meanwhile, vehicle trajectories were extracted from real-life crashes collected from a freeway section of I-94WB This is by far the first data collection efforts that aim to collect vehicle trajectories from real-life crashes to aid car-following modeling. These data were employed in this study to test, calibrate and validate the model. This new model is successful in replicating these vehicle trajectories as well as crashes.
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, Sai
This 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-DOS® 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.

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