Estimation of o-d matrix from traffic counts: How to determine the count locations?

A key issue in the estimation of an origin-destination (0-D) matrix from traffic counts is the identification of a set of links for which flow information should be available to improve the estimation accuracy. This paper investigates how to determine the location of traffic counts and the percentage of links counted in order to guarantee the quality of the O-D matrix estimated from the link flow information. It also reviews different sampling strategies for selecting links with flow information, together with their difficulties in applications. In this paper, link selection and estimation reliability indices are defined together with a systematic sampling procedure which is proposed for choosing traffic count locations particularly when there is no prior O-D and link flow information. Its computational results on a test network are reported with respect to the existing O-D estimation techniques. Finally, some conclusions are drawn for the application of the O-D estimation models.