A generalized and efficient algorithm for estimating transit route ODs from passenger counts

An algorithm is presented for transit passenger OD estimation. The algorithm, like some other existing OD estimation techniques, generates estimates based upon passenger boarding and alighting counts at each stop along the route. The algorithm is distinct in that it does not only estimate an OD matrix for the vehicle trip from which the boarding and alighting counts were taken. Rather, it further estimates the passenger alighting probabilities at every stop on the route and these are more apt to remain fixed across transit trips. Therefore, when coupled with projected boarding counts, the alighting probabilities better characterize OD patterns on the route. These probabilities, moreover, are estimated in such way as to reflect the passengers' latent tendencies to travel to and from "major activity centers" where trip-making is induced. The algorithm is therefore a more general-use method than is the estimation technique proposed by Tsygalnitsky. Since the algorithm does not require a seed matrix, and since the number of iterations required for generating estimates is specified a priori, the algorithm is easier to apply and more computationally efficient than the balancing method of OD estimation.