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原文传递 Irregularly Sampled Transit Vehicles Used as a Probe Vehicle Traffic Sensor

题名：	Irregularly Sampled Transit Vehicles Used as a Probe Vehicle Traffic Sensor
作者：	Daniel J. Dailey, Chandrasekar Elango
关键词：	performance monitoring, probe vehicle technique; transit vehicles, measurement model, travel-time and speed, traffic condition.
摘要：	Performance monitoring is an issue of growing concern both nationally and in Washington State. Travel-times and speeds are a key measure in performance. In this project, we use transit vehicles as probes and develop a framework for modeling die time series that arise from sampling transit vehicle locations as a function of time. These samples of vehicles’ location are obtained from the King County Metro Automatic Vehicle Location (AVL) system. An optimal filter method is developed that estimates speed as function of space and time. In this work, an optimal solution for the state vector, containing the variables’ speed and position, is possible at each step using the Kalman filter result This type of filter solution requires die creation of a model for the process; in this case, a relationship between location and time for the vehicles and the creation of a measurement model to account for measurement errors. The use of such formalism depends upon the assumption that the deviations of the actual system from the idealized model are normally distributed. The model was applied against data from both freeways and arterials to test this assumption. In most ranges of travel, the resulting probability of distribution membership is on the order of 0.9, indicating that the assumption of normally distributed errors is indeed a good one.
报告类型：	科技报告