Optimal Sensor Placement for Freeway Travel Time Estimation

This article presents a modeling framework and a polynomial solution algorithm for determining optimal locations of point detectors used to compute freeway travel times. First, an objective function is introduced to minimize the deviation of estimated and actual travel times of all individual sub-segments of a freeway route. By discretizing the problem in both time and space, we formulate it as a dynamic programming model, which can be solved via a shortest path search in an acyclic graph. Numerical examples are provided to illustrate the model and algorithm using microscopic traffic simulation and GPS data from the Mobile Centuryexperiment recently conducted by the University of California, Berkeley, Nokia and California Department of Transportation (Caltrans).