Evaluation of Count Location Selection Methods for Estimation of O-D Matrices

Origin-destination (O-D) trip matrix estimation from traffic count surveys is regarded as the most economical and effective methodology in road network analysis for transport planning and traffic management. Despite the numerous mathematical estimation techniques previously developed, the fundamental procedure of selecting count locations itself is a prime determinant in the quality of the ultimate estimation and deserves more in-depth exploration. In this paper, some existing methods being adopted in practice are reviewed. Two basic rules are established based on previous works and are formulated in a linear programming model to determine the best survey locations for O-D estimation. However, technical problems will be incurred when applied to a large network with huge number of variables involved. The proposed maximal O-D selection method is proved to provide results with a comparable level of reliability, and a sensitivity test is conducted with different objective functions to verify this proposed strategic algorithm. This paper examines the efficiency of additional link counts for O-D estimation and recommends an efficient data collection method. The models and algorithms are illustrated with numerical examples.