Travel Demand Model - OKI

OKI/MVRPC Travel Demand Model – Version 6.0Table 3-3 TANK Ridership and Survey Expansion FactorsRouteNo ServiceBOARDINGSON-BOARD SURVEYUnlinked Linked No.Obs Exp.Fact Unlinked Linked % Diff.1 Local 1951 1720 317 6.155 1951 1765 3%2 Local 165 165 03 Local 445 393 87 5.115 445 377 -4%4 Local 137 131 14 9.786 137 137 5%5 Local 763 677 84 9.083 763 637 -6%6 Local 720 652 154 4.675 720 658 1%7 Local 698 622 83 8.410 698 649 4%8 Local 422 384 15 28.133 422 380 -1%9 Local 273 251 8 34.125 273 273 9%10 12 12 011 Local 582 536 147 3.959 582 544 1%12 Local 577 482 97 5.948 577 510 6%16 Local 418 372 78 5.359 418 372 0%17 Express 208 186 108 1.926 208 189 2%18 Express 103 101 22 4.682 103 94 -7%19 81 78 020 Local 146 124 021 Local 14 11 022 37 37 023 Local 233 204 81 2.877 233 211 3%24 Local 668 564 211 3.166 668 629 12%25 168 165 026 71 69 027 28 25 030/31 Local 158 142 9 17.556 158 158 11%32 50 48 033 39 37 17 2.294 39 37 1%Total 9167 8188 8395 7620Transfers 11% 9%Surveyed 8395 7454Transfers 11%a Source: Ghafoor Z. Analysis of Observed Transit Ridership in OKI Region for 1995. OKI Travel Demand TechnicalMemorandum, February 1998.The survey data do not differentiate local bus trips from express bus trips. This is problematicbecause SORTA runs several bus routes which provide local, limited stop and express service, allwith the same route number. While there are plausible ways to decide whether a surveyobservation corresponds to a local or an express bus, the usefulness of doing so is limited by thefact that both services charge the same fare. This means that, for estimation purposes, the twoservices are equal but for their running times, which implies that there is virtually no competitionbetween them (i.e. no time vs. cost tradeoff), other than perhaps in waiting times (assumingexpress service has longer headways than local service). Under these circumstances it is difficult,and often impossible, to consider the two services as separate estimation modes. This issue isfurther discussed in the next sections, along with the model estimation results.A final issue with the On-Board Survey is the question regarding transit access and egressmodes. Instead of asking for the mode used to initially access transit (i.e. the first transit vehicleof the trip), the questionnaire requests the mode in which the current vehicle was accessed.Thus, the initial access (or egress) mode for passengers who transferred from another transitvehicle is unknown. For estimation purposes it was assumed that these passengers walked tothe first transit vehicle (access mode), or walked from their last transit vehicle to their finaldestination (egress mode).Mode Choice - Estimation File Preparation 13