Steven E. ShladoverJoel VanderWerfDavid R. RaglandChing-Yao Chan...
p.1-9页
查看更多>>摘要：This paper describes the design and preliminary evaluation of the criteria for alerting drivers to a specific set of intersection hazards. The research is being conducted as part of the development of an intersection decision support (IDS) system that uses the sensing and computational technologies of infrastructure-based intelligent transportation systems. The IDS system under consideration is intended to help drivers avoid conflicts with oncoming traffic when they are making left turns under a permissive (i.e., unprotected) green signal. These conflicts account for a significant proportion of intersection crashes and are difficult to mitigate without imposing serious costs and burdens on intersection capacity associated with providing a protected left-turn signal cycle. The human factors and sensing issues that need to be considered in designing the system are discussed and are followed by a description of the logic used to define the gaps in opposing traffic that should be considered adequate for left-turn maneuvers. The simulation model used to evaluate alternative system designs is described, and sample results are shown for evaluation of the effectiveness of a warning under a relatively stressful scenario. The influence of alternative sensor configurations on the effectiveness of the warning is illustrated and indicates the importance of providing information about both the presence and speed of approaching vehicles sufficiently far from the intersection.
Ching-Yao ChanDavid R. RaglandSteven E. ShladoverJames A. Misener...
p.10-19页
查看更多>>摘要：Intersection collision warning systems can potentially reduce the number of collisions and associated losses. A critical design aspect of these systems is the selection of warning criteria, which represent a set of conditions and parameters under which the decision and the timing to issue warnings are determined. Proper warning criteria allow the generation of timely signals for drivers while minimizing false and nuisance alarms. The paper describes the development of a methodology to observe and analyze the selection of time gaps exhibited by driver behaviors in a real-world setting. The data collection procedures and analysis techniques are explained for left-turn across-path-opposite-direction scenarios, which constitute more than a quarter of crossing path crashes at intersections. Exemplar data sets from an urban, signalized intersection are used to illustrate methods of deriving time gap acceptance behaviors. The extracted information can serve as the basis for selecting gap acceptance thresholds in warning criteria, and the demonstrated methodology can be applied in the development of intersection collision warning systems.
查看更多>>摘要：This paper presents a methodological approach for validation of advanced driver assistance systems. The methodology relies on the use of randomized algorithms that are more efficient than conventional validation that uses simulations and field tests, especially with increasing complexity of the system. The methodology first specifies the perturbation space and performance criteria. Then, a minimum number of samples and a relevant sampling space are selected. Next, an iterative randomized simulation is executed; then the simulation model is validated with the use of hardware tests to increase the reliability of the estimated performance. The proof of concept is illustrated with some examples of a case study involving an adaptive cruise control system. The case study points out some characteristic properties of randomized algorithms with respect to the necessary sample complexity and sensitivity to model uncertainty. Solutions for these issues are proposed as are corresponding recommendations for research.
查看更多>>摘要：In efforts to reduce traffic accidents and improve the efficient utilization of existing transportation networks, increasing attention is being given to the use of wireless communications between vehicles and roadside equipment to develop new intelligent transportation system (ITS) applications that can help improve the safety of transportation networks and reduce urban congestion. Of particular interest for the development of such applications are the currently proposed dedicated short-range communication (DSRC) wireless standards. This paper aims to provide transportation researchers and engineers with an introduction to these standards. The paper presents the current mobile wireless communication applications and standards, the various DSRC standards that have been proposed, their potential use in ITS applications, their envisioned implementation benefits, and the remaining research needs.
查看更多>>摘要：This paper explores the effectiveness of relying on commercial radio as a source of traveler information and presents an approach to quantify mobility benefits from radio traffic advisories. The study, conducted for the Washington, D.C., metropolitan area, used an analytical technique called the heuristic online web-linked arrival time estimator to examine whether broadcast traffic advisories could have mobility benefits similar to a prospective notification-based traveler information service offering personalized estimates of travel times. Traffic reports were recorded from a local radio station and manually coded to translate them into a suitable format for analysis. Results from the analysis of 37 weekdays consisting of 4,410 advisories indicated that radio traffic advisories were less effective in improving traveler on-time reliability or reducing travel disutility than a service offering route-specific travel time reports. The simulated commuter receiving regular quantitative estimates of travel times on relevant roadways typically made more effective route and trip-timing decisions than the simulated commuter receiving comparatively incomplete, irregular, and vague advisories on prevailing congestion conditions from broadcast traffic reports. In contrast, the simulated commuter listening to radio advisories recorded similar benefits to those of the simulated control subject, who ignored all forms of traveler information. During the morning peak period, the simulated radio listener fared worse than the simulated control subject and recorded lower on-time reliability performance and higher travel disutility. During the afternoon peak period, the simulated radio listener had lower travel disutility but also experienced a nominal reduction in on-time reliability performance.
查看更多>>摘要：The development of an intelligent transportation system (ITS) architecture has attracted increasing attention across the world because such an architecture provides a common reference for the ITS community. Standardization of procedures in the development of an ITS architecture is necessary and urgent because of the architecture's inherent complexity, which requires the involvement of several development teams. Although a computer-aided systems engineering model is widely adopted to accomplish parts of the development task, BO far no countries define a strict, clear, and applicable procedure to aid the development teams. This paper first briefly introduces the general methodology for the development of ITS architectures. Then it describes the reasons why a new development tool is needed and examines the components of this development tool. This tool provides developers with support by simplifying and standardizing the entire procedure of ITS architecture development. It reduces developers' workload significantly, improves efficiency, and ensures completeness and consistency of the ITS architecture. It is the first attempt to integrate every step of ITS architecture development procedure into a single package, which has proved to be of great help for Chinese development teams in accomplishing this task effectively and easily in a sustainable way.
Mohammed A. HadiDiane QuigleyPrasoon SinhaLiang Hsia...
p.57-63页
查看更多>>摘要：The Intelligent Transportation Systems (ITS) Deployment Analysis System (IDAS) is a sketch planning analysis tool that can be used to estimate the impacts and costs resulting from the deployment of ITS components. The program includes default values for the parameters required to calculate ITS deployment costs and benefits. IDAS allows users to override the default values of ITS device cost and benefit parameters, including unit cost estimates, cost assumptions, benefit module parameters, ITS impacts, and impact dollar values. On one hand, the use of cost and benefit parameter values that better represent the region under consideration is expected to produce better assessments of ITS deployment alternatives. On the other hand, collection of regional ITS cost and benefit parameters could be expensive, and some required parameters might not be available for the region under consideration. For this reason, IDAS users tend to use many of the program's default values in their analyses. This paper reports on the results of a project that was initiated by the Florida Department of Transportation to identify Florida-specific cost and benefit parameters for use as inputs to IDAS ITS alternative assessments in Florida. The paper also compares the results obtained by using these derived parameters with the results obtained by using the national defaults when a real world ITS deployment project is being evaluated. The produced cost estimate for this deployment project is also compared with the actual cost of the project.
查看更多>>摘要：Road construction on major freeways is a primary cause of traffic incidents and delays. One approach to improve traffic mobility and safety in construction work zones is to use intelligent transportation systems (ITSs), which can effectively enhance work zone traffic management through advanced surveillance and communication technologies. Although conceptually similar to a traditional advanced traffic management system, a work zone ITS has unique network and communication design requirements. The Palm Beach County, Florida, Interim Traffic Management System (ITMS) was a work zone ITS that was successfully deployed in the summer of 2003. Using Palm Beach County ITMS as an example, this paper provides technical guidelines for applying cutting-edge technologies, such as wireless communication, video compression, and Internet protocol encapsulation, in designing a work zone ITS.
查看更多>>摘要：The use of intelligent transportation systems (ITSs)—the application of information and communication technology to road transportation—is emerging to address a variety transportation-related problems. While countries with developing and transitional economies can learn a lot from the ITS experiences of developed countries, they need to develop their own approaches to ITS. The reasons for this are the high speed at which ITS technology is advancing to bring better performance at lower costs and the arrival of new, innovative approaches for both the initial incentives for introducing ITS and the actual introduction process. To support these new opportunities, the World Bank developed a series of five ITS Technical Notes for countries with developing and transitional economies and appendixes that include the 130 examined cases of ITS deployment. The purpose of this paper is to introduce and provide highlights from the ITS Technical Notes. In particular, on the basis of the ITS Technical Notes, this paper (a) explains the new incentives for introducing ITS, particularly in developing countries, that focus on reliability as well as on social benefits; (b) discusses a number of innovative approaches; and (c) introduces a model to assist the selection of the proper application. The model helps decision makers to select the right applications and also informs users about the requirements of the recommended applications. The model presented here can provide useful guidance and a study tool to help users in developing countries to achieve maximum benefits from ITS.
查看更多>>摘要：Exploitation of in-vehicle information technology (e.g., mobile computing and wireless communications) in surface transportation systems is a clearly emerging trend. Equipping vehicles with computing, communication, and sensing capabilities presents significant opportunities for a vast array of transportation services. Vehicle-to-vehicle (V2V) communication may be considered for applications such as incident detection, crash reporting, traveler information dissemination, and network operations. In-vehicle computing systems facilitate the customization of information services to the needs and characteristics of individual travelers. In addition, these systems allow coverage to extend beyond areas where roadside equipment has been placed. This study provides the initial investigation needed to test the feasibility of these advanced communication networks. Several observations may be drawn from the study. First, V2V communication is a feasible way to propagate information along the I-75 freeway in the Atlanta, Georgia, area during peak or high-density traffic periods. With sufficient fleet penetration ratio and traffic density, information can quickly propagate through the system. Second, the simulation methodology described in this study allows researchers to estimate the required fleet penetration ratio for effective communication given the traffic density and application requirements. Third, delay in message propagation is highly variable until instrumented-vehicle density reaches a critical mass. For applications requiring highly reliable, minimal message propagation delay, it may be necessary to design networks that provide extra support to avoid such variation. Research is required to examine additional traffic conditions (e.g., congestion due to an incident) and study the effectiveness of this approach for particular applications.
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