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A GIS-based Multi-Objective Optimization Tool for the Development of the Migration Plan for Next-Generation Controllers
| Content Provider | Semantic Scholar |
|---|---|
| Author | Abbas, Montasir M. |
| Copyright Year | 2013 |
| Abstract | Decisions about upgrade of traffic signal equipment are often made relying on the experience of the senior traffic engineers. Analysis often bases on conventional techniques such as before-after analysis, pilot studies, etc. Factors considered are the deployment time of the system, new technology available, and the performance of the system in the area under purview. Previous research has not defined guidelines or methods for developing a plan for the system replacement decision on a large scale. In addition, previous projects have not considered space and time for deployment of new signal control equipment. This paper presents methodology and a tool for large-scale signal-controllers migration plan. Methodology bases on the functional requirements of the next generation signal-control system. A tool is developed in Geographic Information System (GIS) environment. Upgrade plan is defined on a zone level and bases on optimizing budget constraints, control benefits and spatial distribution of equipment replacement. The entire evaluation methodology for the migration plan was demonstrated on signal control system of Northern Region of Virginia Department of Transportation. INTRODUCTION Traffic signals are considered as one of the vital control elements of the modern traffic management systems, directly affecting transportation networks parameters of mobility, safety, and environment. Today, there are more than 0.27 million traffic signals installed in the United States [1]. Some of the Departments of Transportation (DOTs) today are responsible for traffic signal control systems having over 1000 signalized intersections. Frequently, these vast signal control systems have obsolete and aging technology. Systems in this situation have an essential requirement for upgrade to the next generation of signal control system. Previously, DOTs nationwide have developed plans for upgrade without defined set of guidelines for system replacement decision [2, 3]. System improvement plans were based on conventional techniques, and when the growth or change in traffic demand become evident indication for the improvement need [4]. Some agencies adopt the before and after studies using simulation to evaluate the benefits of system upgrade. In some cases, the process includes reviewing the volume of the intersections or arterials, prioritization based on volumes, identifying the needs and requirements, setting up goals and objectives, and proceeding with the system upgrade. Some of the previous projects [5, 6] dealing with developing plans for future signal systems had no clear recommendations or detailed upgrade plan developed. Frequently, transition to next generation signal system is per intersection – in the case of existing equipment failure or with the introduction of new traffic signal. The upgrade of signal control system can rarely be instantaneous. The reasons for this are such as: Wide spatial area under purview, Direct impact of upgrade process on transportation users safety and mobility, Time required for installation and integration of the equipment Budget constraints and federal funding opportunities Agency's work schedule and availability of resources Requirement for adjusted operations while in transition period As empirically noted by some agencies, maintenance staff, even while working in full capacity, can rarely install more than 200 signalized intersections per year [3]. In addition, the upgrade to new signal controllers has potential for simultaneous upgrade of other infrastructure (such as communication, detection, lanterns, mast arms, etc.) and potential for signal retiming. The research presented here is focusing on developing a methodology and a tool for large-scale upgrade to a next-generation signal-control system. The methodology and tool are developed for the needs of the Northern Region Operations (NRO) of the Virginia Department of Transportation (VDOT). NRO wanted to determine when/if the existing system should be replaced or retrofitted to a certain extent. In order to incorporate different economical, operational and installation constraints, there is a need to develop a strategic migration plan that would indicate the spatial location and time schedule for the upgrade. Since no previous research had dealt with such a migration plan, there is a need for developing a comprehensive but flexible methodology and a tool for finding an optimal migration plan for NRO next-generation signalcontrol system. Geospatial information in signal control systems Transportation agencies are facing with constant increase of the information scope to support effective decision making related to traffic signal infrastructure. Furthermore, wide economic and environmental development problems require sharing of data and agency cooperation at all levels [7]. Since traffic signal infrastructure can have a wide spatial range, information on temporal and spatial relationships is one of the critical steps in the decisionmaking process. In addition, there is an intuitive cognitive power of agency traffic engineers related to the spatial component of signal infrastructure. Geographic Information System (GIS) is recognized as a technique that can significantly enhance the development of the optimal migration plan. GIS can fulfill an essential requirement for manipulating spatial data in different forms and obtaining information related to spatial and temporal components of the system. According to its definition, GIS integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information [8]. The early benefits of GIS were obtained from its ability to store, retrieve analyze and display spatial information. GIS is used for spatial analysis, spatial modeling and spatial statistics for visualization, data management and geographical modeling in different infrastructure management issues [9]. In the area of transportation, GIS has applications on planning, design, construction, operations and management level. Applications of GIS are in regional transportation planning [10], signal control [11], site impact analysis [12], real-time visualization [13], determination of infrastructure needs and utility management [14-18], crash analysis [19] and transit surveying [20]. These research cases have proven GIS as a powerful tool for data representation and analysis in transportation applications. FRAMEWORK AND METHODOLOGY Conventional approaches to upgrade of signal control equipment mainly base on expert knowledge of agency's traffic engineers. The main factor in these decisions was equipment's field deployment time. This has usually limited the information scope and level of details in analysis. However, developing a large-scale migration plan needs to include several framework constraints: 1. Budget, funding, and resources constraints 2. Numerical form of information regarding signal controllers 3. Spatial distribution of local information on traffic demand, patterns and users 4. Spatial distribution of upgrade process The development of strategic migration plan bases on the goal of having exact points in time and spatial location for each intersection upgrade. Developed framework is intended to be flexible to compare performance of system in different conditions, incorporating local information and expert knowledge from the area under purview. In order to develop an effective migration plan, it is most important to know the existing system functional capability. The decision on the most suitable future system directly relates to the functional requirements (FR) for the next generation system. This framework assumes the availability of extensive database on controller performance. From the information on the controller's features and FR for future system, an evaluation criteria can be developed. Using that criteria and Multi-Criteria Decision Making techniques [21], analyst can obtain numerical score of controller functional capability. That score is defined by the term “Performance Index” (PI), and is used to calculate the difference between existing and alternate systems capabilities. The migration plan framework allows several hierarchical levels. Level can be per intersection, per group of intersections (zone), or for the whole system. Having a specific hierarchical level has different advantages and disadvantages, related to analysis scale. Hierarchical level recommended by this research is a zone level. The reasoning for this is twofold, integrating reasons from installation and operations perspective (Figure 1). The grouping in zones allows a certain level of aggregation for easier process of upgrade. On the other side, this hierarchical level is still having significant level of flexibility for determining different functional requirements and levels of importance per zone. Intersections in a zone usually belong to the same corridor, have similar traffic characteristics and functional requirements for future system operation. For example, some intersections are already grouped in their operation and are simultaneously optimized using some commercial optimization software. In addition, some intersections belong to same maintenance plans and sectors. These intersections will be probably upgraded as a group, thus simplifying the workload during migration process. Empirical information from signal control experts should be included in the process of intersection grouping. A general recommendation is that groups of intersections should not exceed a number of 50 intersections. Figure 1: Criteria for grouping of intersections Methodology Considering the framework guidance and constraints, the initial step in the methodology is to determine zone for each intersection (Figure 2). The classification of intersections into zones for upgrade should later become the attribute information of GIS model, with every intersection having a zone ID assigned to it. All |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://milosm.info/Professor%20Milos%20Mladenovic%20publications/A%20GIS-based%20Multi-Objective%20Optimization%20Tool....pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
