Travel Demand Model - OKI

OKI/MVRPC Travel Demand Model – Version 6.0and home-based other trips as follows:• Zero autos per household,• More than 0.0 but less or equal to 0.4 autos per household,• More then 0.4 but less or equal to 0.8 autos per household,• More than 0.8 autos per household.The HBW stratification intends to capture the availability of a car for each worker in thehousehold. It can be reasonably expected that, in households where there are more workersthan cars, the likelihood of share-riding or transit use would be higher than in households withequal or higher number of autos than workers. Note however that the current HBW marketsegments do not differentiate the "less autos than workers" segment. This segment, regardlessof the number of workers or autos, is included in the fifth class listed above, together withhouseholds with two cars and two workers (i.e., same number of autos as workers), andhouseholds with two or more workers and more cars than workers. Alternative marketsegmentations will be explored as part of the model estimation process, with particular attentionto vehicle availability vis-a-vis household workers.The HBO stratification presented above has little, if any, behavioral basis. The per capita autosper household values used to define the various segments are completely artificial, and do notcorrespond to any known behavioral rule, theoretical or empirical. In lieu of this classification, asegmentation based on household auto ownership (0, 1, 2, 3 or more autos per household) willbe explored.The final element of the market segmentation strategy is the use of the potential for walking totransit to calculate walk times. This segmentation stems not from behavioral considerations, asis for example the use of auto ownership, but from the need to better represent actual walkingtimes at the origin and destination ends of a trip. This segmentation recognizes that on anygiven zone, some trip-makers will have easy access to transit, others will require a long walk, andyet others will start or end their trip too far to walk to transit. Consequently, the walking time totransit will vary within each market segment. This is a considerable improvement over thepractice of assuming that everyone is at the same average distance to transit. This transit accessmarket segmentation is used only in model application; for a description of walk times used inmodel estimation see Section 3.5.To apply the transit walk access segmentation, the transit market is segmented into sevengroups, depending on the proportion of trips within short, long, or no walk, both at the origin anddestination zones (see Table 2.1). For the OKI/MVRPC model, a short walk is 1/6 of a mile orless, and a long walk is between 1/6 and 1/3 of a mile. Within each market segment, the transitwalk time is estimated as the minimum of a pre-specified time (see Table 2.2) and the walk timeestimated from the transit skims.Table 2-1 Walk Distance to Transit Market SegmentationDestination ZoneWalk Distance Short Long No WalkShort short -> short short -> longOrigin ZoneLong long -> short long -> longNo TransitNo Walk drive -> short drive -> longMode Choice - Mode Choice Model Specification 7