摘要 :
This report is a comprehensive investigation of adaptive signal control. Congestion, incidents and transit priority all are discussed and examined by modeling, first on a theoretical network, and then on four Salt Lake City area n...
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This report is a comprehensive investigation of adaptive signal control. Congestion, incidents and transit priority all are discussed and examined by modeling, first on a theoretical network, and then on four Salt Lake City area networks using field collected data. This modeling was possible through the University of Utah-built interface between the micro-simulation models CORSIM and VISSIM and the Split, Cycle and Offset Optimization Technique (SCOOT). The findings of this two-year study show that adaptive control has substantial benefits over a non-adaptive system. The results presented are compared to an updated and optimal fixed-times system-the best that an experienced traffic engineer can achieve, short of adaptive control. This report concludes with a firm recommendation to deploy adaptive signal control. The research shows that adaptive control in SLC will bring immediate delay reduction and improved traffic control for many years to come.
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Adaptive Traffic Control Systems (ATCSs) adjust, in real time, signal timings based on the current traffic conditions, demand, and system capacity. The systems require extensive surveillance, historically in the form of pavement l...
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Adaptive Traffic Control Systems (ATCSs) adjust, in real time, signal timings based on the current traffic conditions, demand, and system capacity. The systems require extensive surveillance, historically in the form of pavement loop detectors, and infrastructure that allows for communication with the central and/or local controllers. Although there are at least 25 ATCS deployments in the United States, these systems may not be well understood by many traffic signal practitioners in the country. Their operational benefits have been demonstrated, but there are still some reservations among individuals in the traffic signal community. These systems are considered expensive and complex and they require high maintenance of detectors and communications. Although a few short surveys have been done, there has been no comprehensive survey that has addressed major problems with ATCS implementations. The study methodology included three sequential efforts. The first focused on the selection of ATCSs, which are typically deployed in the United States (and worldwide), and identification of ATCS agencies that could be interviewed. The next effort was to conduct a literature review and gather as much information as possible about ATCS operations and deployments from previous studies. Finally, two electronic surveys were conducted: a shorter e-mail survey for ATCS vendors and a longer web-based survey for ATCS users. Responses were obtained from 34 of 42 agencies in North America, an 81% response rate. Also, responses were obtained from 11 agencies in other countries. Municipal and county traffic operations agencies were the primary contributors among the 45 agencies that responded to the survey.
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摘要 :
The document discusses the highway operations, capacity, and traffic controls. Italso includes the advanced traffic management systems and automated highway systems.
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The report presents a traffic control system, called the Area-Wide Real-TimeTraffic Control (ARTC) System, which addresses occurrences of congestion and provides areawide traffic progression. The signal controllers in ARTC are int...
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The report presents a traffic control system, called the Area-Wide Real-TimeTraffic Control (ARTC) System, which addresses occurrences of congestion and provides areawide traffic progression. The signal controllers in ARTC are interconnected through a communication network and by exchanging traffic flow information among them, ARTC provides a new concept in areawide traffic control. The traffic area controlled by ARTC is divided into regions and a regional controller is provided for each region. The regional controller periodically collects traffic flow information from the signal controllers to view the traffic flow of its region and anticipate congestion by detecting changes in traffic flows. Once congestion is anticipated in a region, the influx of traffic into this region is reduced until the congestion situation disappears. The signal controllers and the communication network are designed to support the real-time traffic control. Fault-tolerant designs for the signal controller and the network are also presented.
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The existing models and strategies for optimal adaptive control according to thelarge scale systems theory are limited in operational size as a result of the large number of dimensions. It is proposed to overcome the problem by po...
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The existing models and strategies for optimal adaptive control according to thelarge scale systems theory are limited in operational size as a result of the large number of dimensions. It is proposed to overcome the problem by positioning the adaptive control in the lowest layer of a hierarchical control system (the individual traffic facilities). Given the non-linearity of the models and the quick changes, a 'gain-scheduling' control is favored. A second control layer coordinates the control in each of the individual traffic facilities and accounts for the traffic states on the interfaces with neighboring subsystems. In a third control layer the working modes for all the lower layers are selected and set-points, coefficients, constants and weighing elements are set and regulated. More individual safety criteria can be incorporated as constraints in the adaptive control.
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The Minnesota Department of Transportation, in cooperation with Hennepin County211 and the cities of Bloomington, Edina and Richfield, is conducting an operational 211 test of an integrated corridor traffic management system (ICTM...
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The Minnesota Department of Transportation, in cooperation with Hennepin County211 and the cities of Bloomington, Edina and Richfield, is conducting an operational 211 test of an integrated corridor traffic management system (ICTM). The test 211 involves an eight-mile-long segment of I-494 in the Twin Cities metropolitan area 211 and the adjacent arterial street system, shown in Exhibit A. In general, the test 211 involves the phased implementation of an adaptive traffic control system with 211 both freeway ramp meter and arterial traffic signals with the ability to 211 continuously adjust timing plans in response to real-time flow conditions. This 211 interim report documents the evaluation analysis of the initial ICTM project 211 implementation phase involving Modules 1 and 2 which includes adaptive controls 211 at 27 ramp meters and integration with the existing freeway management system 211 (FMS) as Module 1.
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The study was performed to develop the Area-Wide Real-Time Traffic Control (ARTC) System which uses real-time traffic flow information and design signal timing plans online. The ARTC system consists of microcontrollers at each int...
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The study was performed to develop the Area-Wide Real-Time Traffic Control (ARTC) System which uses real-time traffic flow information and design signal timing plans online. The ARTC system consists of microcontrollers at each intersection to perform signal timing computations which are connected to each other by a communication network. The signal controllers exchange traffic flow data to aid in the signal timing computations. A simulation of the ARTC system was performed and compared with a fixed time control which was computed using the TRANSYT7F program. Results of the simulation show significant savings in delay and stops by ARTC over fixed time control. Under the ARTC system, signal controllers must process large amounts of real-time traffic information and communicate with neighboring signal controllers while making traffic control decisions. A modification of the TYPE179 controllers to suit the needs of the ARTC system and future traffic management systems may be expensive and infeasible. A design of the signal controller using the microcontroller MC68332, which has the desired features for a typical signal controller, is also presented.
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Adaptive Control Software Lite (ACS-Lite) is a traffic signal timing optimization system that dynamically adjusts traffic signal timings to meet current traffic demands. The purpose of this research project was to deploy and evalu...
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Adaptive Control Software Lite (ACS-Lite) is a traffic signal timing optimization system that dynamically adjusts traffic signal timings to meet current traffic demands. The purpose of this research project was to deploy and evaluate the ACS-Lite adaptive traffic control system on a congested urban corridor in New York State (NYS). In this case, the Wolf Road Corridor in Albany, New York, was chosen. The primary goal was to document the experiences and key lessons learned from the deployment and evaluation regarding how an adaptive control system can be deployed, the advantages and disadvantages of the system, and whether it is suitable for use in other corridors in NYS. The results of the project showed that for heavily congested corridors adaptive control can improve flow within its own system, but may cause extra delays at the boundaries where there are interactions with other traffic control systems. Therefore, a more comprehensive control/management framework may be needed in some cases. The specific ACS-Lite software also needed to be upgraded and improved in order to work for the selected corridor, which caused delays to this project.
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Simulation has been utilized in the planning and development of almost all sectors of the transportation field. The practicing transportation community primarily relies on simulation packages. When a practitioner (or end user) use...
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Simulation has been utilized in the planning and development of almost all sectors of the transportation field. The practicing transportation community primarily relies on simulation packages. When a practitioner (or end user) uses a simulation package, most of the simulation development efforts have already been completed. Unfortunately, the use of these simulation packages has several disadvantages, most notably the 'black box' phenomenon and reduced modeling flexibility. The simulation model described in this research lays the foundation for a transportation simulation, OPEN-TS3, that minimizes the black box problem and increases modeling flexibility, while still providing an easy to use package in which highly capable models may be quickly and accurately built. The approach to simulation in this research is to develop a platform that allows for the use of existing constructs where applicable, while still retaining the flexibility for the user to incorporate new basic modeling constructs. OPEN-TS3 utilizes SIMAN (a simulation language) and ARENA (a simulation development tool), both commonly found in manufacturing applications. As a demonstration of the flexibility of OPEN-TS3 two adaptive signal control strategies are also successfully implemented. The adaptive control strategies are tested on three different networks under varying volume conditions. Based on the OPEN-TS3 simulations it was seen that adaptive control can provide superior overall performance, but can have a significantly greater range of variability than that of pre-timed control.
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