Travel Demand Model - OKI

OKI/MVRPC Travel Demand Model – Version 6.06.2 Trip Generation Estimates, with Scale FactorsScale factors, both for HBW and HBO productions and attractions, were estimated in the highwayvalidation phase. The production scale factors were adjusted to match estimated VMT withineach region to the observed VMT. The process of adjusting these factors involves severalsensitivity tests of the VMT estimates to each factor. The attraction scale factors were adjustedto improve the validation of screenlines that capture trip interchanges between OKI and MVRPC.This process also involves performing a number of sensitivity tests of the screenline and regionalVMT estimates to each factor. The production and attraction scale factors are adjusted jointly bytrial and error, with guidance from the results of the sensitivity tests. Final factors are shown inAppendix B.Table 6.5 shows the final trip generation model estimates. The effect of the production scalefactors is to reduce the overall trip production, a result required because regional VMT wasoriginally overestimated in both regions. The underlying reason is that the consolidated modelestimates significantly longer trip lengths than the OKI v.5.4 model. Please refer to Part IV (TripDistribution) of the Model Development Report.The effect of the attraction scale factors is to redistribute HBW attractions from the OKI region tothe MVRPC regions, while redistributing HBO attractions from the MVRPC region to the OKIregion. Overall this reduces the number of trip interchanges between the two regions, whichwere originally overestimated. Note however that the main trends described in Section 6.1 aremaintained; namely, there’s a positive flow of HBW trips from the MVRPC region to the OKIregion, and a positive flow of HBO trips from the OKI region to the MVRPC region.The need for attraction scale factors is that the OKI trip attraction models do not fully apply tothe MVRPC region. Original trip attraction models for MVRPC could not be estimated, due to lackof data. Instead, attraction scale factors were introduced to allow control over the allocation ofattractions between the two regions. These scale factors were estimated jointly with theproduction scale factors by adjusting the model regional volume and VMT estimates to theobserved volume and VMT. Special attention was paid to the screenlines, in particular those ator near the border between the two regions.Table 6-5 Final Consolidated Trip Generation Estimates, with Updated Scale FactorsHome-Based Work Home-Based School a Home-Based University Home-Based Other External bRegion Productions Attractions Productions Attractions Productions Attractions Productions Attractions I to EOKI 972,020 1,007,984 13,959 14,021 56,200 55,419 2,838,810 2,867,287 213,976MVRPC 529,615 507,300 2,042 1,994 35,658 37,159 1,132,927 1,177,279 120,104Miami Co. 64,927 57,027 0 0 5,958 5,240 145,495 134,439 32,567All 1,566,562 1,572,311 16,001 16,015 97,816 97,818 4,117,232 4,179,005 366,647Trip Generation - Trip Generation Analysis 37