A generalized model and solution algorithm for estimation of the dynamic freeway origin-destination matrix

This study presents a generalized model for estimating the dynamic freeway O-D distribution, based on measurable time series of mainline and ramp flows, and estimated travel time distributions. The proposed model captures the speed discrepancy among drivers, due either to their desired speeds or responses to congestion, with an embedded travel time distribution function and the identified interrelations between time-varying ramp and mainline flows. With the employed mainline information and travel time function, the proposed system equation has increased its observability with less parameters. The proposed model with a specially designed algorithm offers the potential for use in a network of realistic size, such as the I-95 freeway corridor between the Maryland I-695 and I-495 beltways. Extensive numerical analyses with respect to the sensitivity of both input measurement errors and the selection of initial parameters on the estimation results have revealed that the proposed model is sufficiently robust for real-world applications.