1、毕业设计 (论文 )外文资料翻译 院 系 电气学院 专 业 电气工程及其自动化 学生姓名 班级学号 外文出处 指导教师评语： 指导教师签名 ： 年 月 日 Vehicle Detector Technologies for Traffic Management Applications Part 1 Lawrence A. Klein Consultant Ten different detector technologies were recently evaluated as part of the FHWA-sponsored Detection Technology for IVHS
2、program. The two primary goals of the program were: 1. To determine traffic parameters and their corresponding measurement accuracies for future Intelligent Transportation Systems (ITS) applications, 2. To perform laboratory and field tests with above-the-road mounted, surface, and subsurface detect
3、ors to determine their performance. Detectors representative of all tested technologies were found to satisfy current traffic management requirements. However, improved accuracies and new types of information, such as queue length and vehicle turning or erratic movements, may be required from detect
4、ors for future traffic management applications. The choice of a detector for a specific application is, of course, dependent on many factors, including data required, accuracy, number of lanes monitored, number of detection zones per lane, detector purchase and maintenance costs, vendor support, and
5、 compatibility with the current and future traffic management infrastructure. The results of this evaluation project is being presented in two parts. Part 1 introduces the theory of operation and the strengths and weaknesses of the various overhead detector technologies. Part 2 will provide field ev
6、aluation data and some general conclusions about detector performance and applications. Copies of the Final Report, a set of five compact disks containing the detector evaluation data, and other reports are available from the FHWA by writing to Mr. Pete Mills at HSR-1, 6300 Georgetown Pike, McLean,
7、VA 22101. Note: The detector performance data presented in this article were obtained by Dr. Klein when he was the projects Principal Investigator at Hughes Aircraft Company. INTRODUCTION Maximizing the efficiency and capacity of the existing ground transportation network is made necessary by the co
8、ntinued increase in traffic volume and the limited construction of new highway facilities in urban, intercity, and rural areas. Smart street systems that contain traffic monitoring detectors, real-time adaptive signal control systems, and motorist communications media are being combined with freeway
9、 and highway surveillance and control systems to create smart corridors that increase the effectiveness of the transportation network. The infrastructure improvements and new technologies are, in turn, being integrated with communications and displays in smart cars and public access areas (such as s
10、hopping centers) to form intelligent transportation systems. Vehicle detectors are an integral part of these modern traffic control systems. The types of traffic flow data, as well as their reliability, consistency, accuracy, and precision, and the detector response time are some of the critical par
11、ameters to be evaluated when choosing a vehicle detector. These attributes become even more important as the number of detectors proliferate and the real-time control aspects of ITS put a premium on the quantity and quality of traffic flow data, as well as the ease of data interpretation and integra
12、tion into the existing traffic control system. Current vehicle detection is based predominantly on inductive loop detectors (ILDs) installed in the roadway subsurface. When properly installed and maintained, they can provide real-time data and a historical database against which to compare and evalu
13、ate more advanced detector systems. Alternative detector technologies being developed provide direct measurement of a wider variety of traffic parameters, such as density (vehicles per mile per lane), travel time, and vehicle turning movement. These advanced detectors supply more accurate data, para
14、meters that are not directly measured with previous instruments, inputs to area-wide surveillance and control of signalized intersections and freeways, and support of motorist information services. Furthermore, many of the advanced detector systems can be installed and maintained without disrupting
15、traffic flow. The less obtrusive buried detectors will continue to find applications in the future, as for example, where aesthetic concerns are dominant or procedures are in place to monitor and repair malfunctioning units on a daily basis. Newer detectors with serial outputs currently require spec
16、ific software to be written to interpret the traffic flow parameters embedded in the data stream. Since each detector manufacturer generally uses a proprietary serial protocol, each detector with a unique protocol requires corresponding software. This increases the installation cost or the real purc
17、hase price of the detector. Furthermore, not every detector outputs data on an individual vehicle basis. While some do, others integrate the data and output the results over periods that range from tens of seconds to minutes, producing parameters that are characteristic of macroscopic traffic flow.
18、The traffic management agency must thus use caution when comparing outputs from dissimilar detectors. In performing the technology evaluations and in analyzing the data, focus was placed on the underlying technology upon which the detectors were based 1,2. It was not the purpose of the program to de
19、termine which specific detectors met a set of requirements, but rather whether the sensing technology they used had merit in measuring and reporting traffic data to the accuracy needed for present and future applications. Obviously, there can be many implementations of a technology, some of which ma
20、y be better exploited than others at any time. Thus, a technology may show promise for future applications, but the state-of-the-art of current hardware or software may be hampering its present deployment. The detectors that were used in the technology evaluations during the field tests are listed in Table 1. Not all detectors were available at all sites as shown in the footnotes to the table. A summary of the advantages and disadvantages of the detector technologies is given in Table 2. Some of them are application specific, implying that a particular technology
