Dynamic Origin-destination Trip Demand Estimation for Subarea Analysis

A subarea analysis capability is needed in conjunction with dynamic network analysis models to allow consideration and rapid evaluation of a large number of scenarios and support transportation network planning and operations decisions for situations that may not require analysis on a complete network representation. Focusing on how to provide an up-to-date time-dependent OD demand matrix for the subarea network, this paper describes a two-stage subarea demand estimation procedure. The first stage uses path-based traffic assignment results from the original network to generate an induced OD demand matrix in the subarea network. An excess-demand traffic assignment formulation is adopted to model the external trips that traverse or bypass the subarea network. An iterative bi-level subarea OD updating procedure is incorporated at the second stage to find a consistent network flow pattern by utilizing the induced OD demand information and archived traffic measurements in the subarea network. The proposed procedure is illustrated in a case study using the Los Angeles subarea network extracted from the Southern California Association of Governments regional transportation planning network.