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33 Application of a Microsimulation Model for User Benefit Calculation in Transit Projects Peter Vovsha, PB Consult, Parsons Brinckerhoff Inc. FTA has requirements for a travel demand model thatis used to estimate user benefits (UBs) of transit proj -ects. These requirements are based on the general methodology of UBs as the difference between total com- posite utilities calculated before and after project intro- duction. The current FTA approach limits the cor - responding scope of choices over which the composite util- ity is calculated to mode and route choices. Thus, the total trip table is assumed fixed, and the mode and route choice attributes that are necessary for calculation of the compos- ite mode choice utility are reported. The FTA approach and developed software SUMMIT have been primarily designed for four- step models characterized by an easy dis- integration of the trip- distribution and mode- choice stages as well as the aggregate zone- to- zone structure of the model output. The new generation of activity- and tour- based microsimulation models, of which the Mid- Ohio Regional Planning Commission (MORPC) model is one representa- tive, requires a certain reconsideration of the UB calcula- tions in view of the more complicated structure in which trip distribution and mode choice stages are closely intertwinedâ as well as because of the fully disaggregate (individual- record) structure of the output. In theoretical terms, the behaviorally realistic and detailed output of the new models offers numerous addi- tional possibilities for quantifying UBs of transit projects compared with the composite mode choice utility. How- ever, taking advantage of the activity- based approach for the UB calculation is a long- term issue for which numer- ous methodological and technical details should still be developed. Furthermore, extending the UB methodology for activity- based models (though highly desirable) may create a certain bias in the comparison between regions because some metropolitan planning organizations have already developed activity- based models, while the majority are still using conventional four- step models. Under these circumstances and primarily for practical purposes, a constructive way is proposed to adjust the activity- based model output to the requirements of the conventional UB calculation procedure. The general structure of the MORPC model system and the most important and relevant components are shown in Figure 1. A set of day- level models that corre- sponds to coordinated daily activity patterns for all household members appears as a single upper- level stage with no details because this paper is devoted to mode choice issues. The subset of tour- level models includes the following components: ⢠Primary tour destination model that defines which of 1,805 zones and which of three subzones (with no access to transit, long walk to transit of 0.5 to 3.0 mi, or short walk to transit less than 0.5 mi) are chosen for each tour; ⢠Time- of- day model that defines departure- from- home and arrival- back- home combinations of hours from 5:00 a.m. (or earlier) to 23:00 p.m. (or later). Departure- from- home hour is associated with the out- bound half- tour timing, and arrival- back- home hour is associated with the inbound half- tour timing; ⢠Entire- tour modeâbest transit submode model that defines which one of six principal entire- tour modes is chosen for each tour (1, single- occupancy vehicle; 2,