Strategies for selecting additional traffic counts for improving O-D trip table estimation

Traditional traffic counting location (TCL) problem is to determine the number and locations of counting stations that would best cover the network for the purpose of estimating origin-destination (O-D) trip tables. It is well noted that the quality of the estimated O-D trip table depends on the estimation methods, an appropriate set of links with traffic counts, and the quality of the traffic counts. In this paper, we develop strategies in the screen-line-based TCL model for selecting additional traffic counts for improving O-D trip table estimation. Using these selected traffic counts, the O-D trip table is estimated using a modified path flow estimator that is capable of handling traffic count inconsistency internally. To illustrate the impact of the additional number of traffic counts on O-D estimation, we set up a unique experiment in a real world setting to visually observe the evolution of O-D estimation as the number of traffic counting locations increases. By comparing the O-D trip tables in a GIS, we visualize the actual impacts of counting locations on the estimation results. Various spatial properties of O-D trip tables estimated from traffic counts of different locations are identified as results of the study.