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Accurate estimation of travel time is critical to the success of advanced traffic management systems and advanced traveler information systems. Travel time estimation also provides basic data support for travel time reliability research, which is being recognized as an important performance measure of the transportation system. This paper investigates a number of methods to address the three major issues associated with travel time estimation from point traffic detector data: data filling for missing or error data, speed transformation from time‐mean speed to space‐mean speed, and travel time estimation that converts the speeds recorded at detector locations to travel time along the highway segment. The case study results show that the spatial and temporal interpolation of missing data and the transformation to space‐mean speed improve the accuracy of the estimates of travel time. The results also indicate that the piecewise constant‐acceleration‐based method developed in this study and the average speed method produce better results than the other three methods proposed in previous studies. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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信号电缆故障点检测仪的开发 总被引:3,自引:0,他引:3
介绍了采用TDR方式(时域反射法)开发的信号电缆故障点检测仪。信号电缆在信号安全控制设备中担负重要作用,一旦电缆出现故障,将严重影响列车运营,而且修复电缆需要较长的时间和大量的人力、物力。尽快排除故障,迅速、准确地查找故障点至关重要,为此,开发了采用TDR方式的信号电缆故障点检测仪。该方式广泛适用于线路的阻抗测试,能迅速测量出电缆的断线、混线、浸水等各种故障的具体地点。 相似文献
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广州地铁2号线防淹门系统的设计分析 总被引:1,自引:1,他引:0
结合广州地铁2号线的防淹门系统工程实际,对防淹门系统方案选择、功能设计、接口设计、报警动作原理、成败得失等方面进行了分析。 相似文献
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针对轮轴微机控制超声波自动探伤机存在漏探问题的调查与分析,提出了针对性的解决方案和建议。 相似文献
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Travel time estimation and its variation for urban expressways are vital to both the information provision to road users, and the system evaluation and management for traffic administrators. Fruitful research efforts have been made to develop methodologies of reconstructing spatiotemporal traffic states mainly for freeways based on one or multiple data sources. However, few studies specifically focused on urban expressways. There are more intensive merging and diverging traffic due to short distances between ramps, for example, 300–500 m. Based on the empirical analysis of traffic data collected on a typical segment of a congested urban expressway, this study proposes an extended generalized filter algorithm for the urban expressway traffic state estimation based on heterogeneous data. More specifically, the multiple sources of data include both fixed sensor data (e.g., inductive loops or radar data) and global positioning system (GPS) probe vehicle data. This study compares the proposed algorithm and the traditional algorithm for freeways using data collected on the segment of expressway in Beijing, China. Results demonstrate the advantage of the proposed method, as well as its feasibility and effectiveness. 相似文献
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