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Raj Roy- MS Thesis.pdf (1.75 MB)

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Combining Small Samples of Direct Observations of Passenger Flows with Large Quantities of Automatic Passenger Count Data for Estimating Bus Transit Route Origin-Destination Flows

Roy, Raj
http://rave.ohiolink.edu/etdc/view?acc_num=osu16297059007711

Abstract Details

2021, Master of Science, Ohio State University, Civil Engineering.
The Iterative Proportional Fitting (IPF) method represents the state-of-the-practice for estimating bus route-level passenger OD flow matrices. It requires boarding and alighting volumes along with a seed matrix as inputs. Although the “Null” matrix, where passengers are equally likely to travel between any of the feasible OD pairs, is used as a default seed, empirical onboard survey data provide an informative seed matrix. Due to the small sample sizes of such surveys, some OD pair entries are of low confidence leading to poorer quality OD flow estimates when such an empirical matrix serves as a seed for the IPF method. To improve the quality of OD flow estimates when using an empirical seed matrix, a linearly weighted combination of an empirical OD matrix and some other OD matrix is proposed to form the seed matrix. A Monte Carlo simulation-based approach is developed to evaluate the use of this approach and understand the conditions that influence its impact on the quality of the estimated OD flow matrix. Empirical data from three operational bus routes at two different transit systems are used to determine important input values. The “Null” matrix and the “IPF-Null” matrix, estimated by applying the IPF method with a “Null” seed matrix, are considered as alternatives to be combined with the empirical OD matrix to form the combined seed matrix. Results demonstrate that using “IPF-Null” is preferred to using “Null” to form the seed matrix. Therefore, an investigation of the quality of the estimated OD flow matrix as a function of the quality of the empirical OD flow matrix is conducted using the “IPF-Null” matrix to form the seed matrix. Moreover, the optimum weighting factor used to combine the two matrices to form the seed matrix as a function of the quality of the empirical OD flow matrix is also explored. For onboard survey sample sizes expected in practice, results suggest that if the optimum value of the weighting factor is known, using a combined seed matrix will provide the best OD flow estimates compared to either using the empirical matrix as an estimate or using only the empirical matrix as a seed in applying the IPF method. However, since the optimum value of the weighting factor will be unknown in practice, a sensitivity analysis suggests that in practice, using a weighting factor that is a good approximation of the optimal one is important. To approximate the optimal value of the weighting factor in practice, the relationship between the optimum value and three sample size related measures intended to be representative of the quality of the empirical matrix are investigated. Anecdotal results suggest that the relationship associated with two of the measures may be transferrable to some extent among similarly structured routes and therefore, could be used to determine good approximations of the optimal value of the weighting factor in practice.
Mark McCord (Advisor)
Civil Engineering; Engineering; Transportation; Transportation Planning
origin-destination; bus transit; Automatic Passenger Count; Iterative Proportional Fitting; Seed Matrix; Empirical OD estimation; Monte-Carlo Simulation; onboard survey

Recommended Citations

Citations

  • Roy, R. (2021). Combining Small Samples of Direct Observations of Passenger Flows with Large Quantities of Automatic Passenger Count Data for Estimating Bus Transit Route Origin-Destination Flows [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu16297059007711

    APA Style (7th edition)

  • Roy, Raj. Combining Small Samples of Direct Observations of Passenger Flows with Large Quantities of Automatic Passenger Count Data for Estimating Bus Transit Route Origin-Destination Flows. 2021. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu16297059007711.

    MLA Style (8th edition)

  • Roy, Raj. "Combining Small Samples of Direct Observations of Passenger Flows with Large Quantities of Automatic Passenger Count Data for Estimating Bus Transit Route Origin-Destination Flows." Master's thesis, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu16297059007711

    Chicago Manual of Style (17th edition)

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