The passenger flows between origins and destinations on bus routes is information that transportation planners and operators can utilize in planning, designing, and managing the operations of transit services. Manual methods of collecting data on passenger origin-destination (OD) flows are difficult to implement regularly because they require much planning, time, and personnel. Automatic passenger counting (APC) technologies, which provide comprehensive data collection on the boarding and alighting volumes at all bus stops on a route, are increasingly being installed on bus systems. Typically, the APC data provide planners with insights on bus loads along transit routes. However, APC data may also be beneficial in estimating the difficult-to-obtain passenger OD flow information.
The research presented in this thesis sought to assess the performance of a simple method that can use APC data to estimate passenger OD flows, namely, the Iterative Proportional Fitting (IPF) procedure used with the uninformative null matrix adopted as the base (or seed) matrix. The base matrix is used as an initial starting point in the IPF procedure to produce an output consistent with the APC data. A null base matrix assumes that each matrix cell is equally likely to be observed (i.e., passengers are equally likely to travel along any feasible OD pair). This equally likely specification can be considered a very crude and uninformative starting point that is based on no knowledge of the passenger flow patterns. The null base matrix is considered in this thesis because its simplicity would allow it to be used easily in practice. Given its unrealistic nature in representing OD flows, using the null base with the IPF procedure to produce OD flow estimates may not be expected to produce good estimates. Therefore, it would be important to assess the performance of the IPF procedure with a null base (referred to as the “IPF-null” procedure in this thesis) in estimating OD flows at the bus trip level by comparing it to other benchmarks of estimated OD flows.
Based on a field experiment in which true OD flows were observed, the IPF-null procedure was found to perform relatively well, as compared to a set of benchmark estimates. The results show that OD matrices produced by the IPF-null procedure appear to be of similar quality as matrices derived from on-board survey data. Additionally, the results show that using on-board survey data as a base in the IPF procedure provide OD flow estimates that are better than using an on-board survey alone.
These findings indicate the value of using increasingly available APC data to estimate passenger OD flows, even when using the straightforward IPF-null procedure. It appears that the IPF-null procedure can achieve comparable OD flow estimates at a much lower cost than using standard manual on-board surveys when buses are equipped with APC technologies.