Michalopoulos, Panos

Consideration for motorist safety mandates the establishment of criteria for maintaining effective signing in the event of detrimental factors such as adverse weather conditions, ambient lighting conditions and power failures. In this study, research undertaken by twenty four states/agencies was reviewed and information on current practices concerning illumination and reflectorization of overhead signs was collected to define the most effective sign treatment to be used. The study concludes that the best alternative for sign treatment incorporates both reflectorized background and external illumination.

This study was conducted to develop a rational method for selecting the most appropriate type of traffic control at construction sites involving the closing of a one-lane bridge. The study consisted of a literature review, a survey of practices in other states, the observation of a number of actual construction sites, the collection and analysis of data from these construction sites and finally, the development of methods for estimating the capacity and measuring the effectiveness of various types of traffic control. As a result, a method for selecting an appropriate type of traffic was developed. This method takes into account variables such as sight distance, bridge length, traffic volumes and capacity, consideration of the costs and benefits of various types of control and an analysis of the geometric features of the geometric features of the approaches to the bridge.

This 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. Note: The phase I report is available at https://hdl.handle.net/11299/156893.

This report summarizes the final results of the current project to enhance the KRONOS program. The resulting version, V8.0, being operated under the MS-DOS environment, can handle two freeways merging/diverging with a common section with total length up to 20 miles and eight lanes wide. The input data preparation is performed interactively using pop-up menu screen with a mouse. For instance, the geometrics are entered by selecting the configuration of each segment from the available alternatives presented on the screen. The current version has a total of 26 available segment types, which can treat most of the freeways in the U.S. Further, a new incident simulation module that can handle up to six stages in terms of time-variant capacities is also added to the new version. Following definition of the geometrics of each segment, the entire freeway can be plotted for verification. The other input requirements include the arrival/departure demand pattern at the freeway boundaries and ramps in user specified time intervals (minimum 1 minute). The demand patterns are also plotted for verification and can be as complex as desired. The program allows employment of user-specified flow-density models which are entered interactively. The change to input already entered can be made at any stage during the data entry. Note: The phase I report is available at https://hdl.handle.net/11299/156893.

Among the most promising and innovative concepts today for alleviating urban traffic congestion is the use of video imaging for vehicle detection, automatic surveillance, and advanced control strategies. Because of its conceptual appeal, research in this area was initiated in the mid 70's in the United States and abroad. A system for vehicle detection through video imaging was recently developed at the University of Minnesota and is being implemented on the 1-394 and l-35W freeways in Minneapolis, Minnesota for incident detection. The Minnesota system, called AUTOSCOPE (TM), emulates loop detectors, a large number of which can easily be placed within the field of the camera's view through interactive graphics. In recent tests its performance matched or exceeded that of loops in vehicle counting, speed measurements, and extraction of certain measures of effectiveness. Evaluation tests of the AUTOSCOPE (TM) were very encouraging, thus the system was installed at a traffic intersection to demonstrate the effectiveness of this new technology as a replacement for loop detectors.

A microscopic, stochastic model for intersection design and traffic flow analysis is presented in this report. A simulation program, INTERSIM, based on this modeling, is developed. The INTERSIM program can be used to evaluate alternative control schemes and geometric configurations. INTERIM can also assist in solving traffic operation and management problems, e.g., determining optimum signal phasing and timing of intersections via an iterative process. The most common situations encountered in practice are examined. These include: four-way and T-intersections with up to three lanes on each approach; stop sign control; signal control (fixed time or vehicle actuated) with various phasing schemes; detector placement and functions, multi-use lanes; protected and permissive left-turn movements; and right turns on red, among others. The proposed modeling applies to both over-saturated and under-saturated traffic conditions. INTERSIM is superior to the other intersection simulation programs due to its ease of operation and fast execution speed.

This is a summary of Report 2003-06 "The Employment of the Traffic Management Laboratory (TRAMLAB) for Evaluating Ramp Control Strategies in the Twin Cities."

Report #5 in the series: Access to Destinations Study. The first four in the series are numbered 2006-16, 2007-24, 2007-35 and 2008-11. 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.

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.

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.