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Model Calibration Before performing the future demand forecasting,TJKM calibrated the model to the tum counts collected in 2002 for the Mountain House Parkway/I-205 PSR(TJKM 2002).The network was modified to include all the future study intersections. Based on the collected counts,the a.m.and p.m.turning movement volumes were entered into the"existing condition"portion of the model.TJKM successfully performed the model calibration for the study area by revising the network topology and attributes as well as the Origin-Destination(OD)demand.The model was calibrated to within a relative error of 6%between the computed and observed volumes. Therefore,the model has been calibrated to a high level of accuracy. After the model was calibrated,the difference method was used to obtain future link and tum volumes based on the calibrated model.For additional details,please refer to Demand — Forecasting Methodology for Mountain House Project Study:Final Results prepared by TJKM in October 2002. Truck Climbing Lane — It is noted that Caltrans has recently approved a Truck Climbing Lane PSR.The proposed truck climbing lane project might include one or two additional westbound lanes beginning east of the Mountain House Parkway — Interchange and ending between Grant Line Road and Greenville Road.The project is currently not funded for construction.The existing SJCOG model is a single-mode auto-forecasting model and does not include the truck mode choice.Consequently,the SJCOG model will not be able to represent this project in the model.However, because the intent of the truck climbing lane is to improve the traffic flow on I-205,the current analysis can be considered to be the worst case. A truck climbing lane would not change the worst-case study results identified in this section. Trip Distribution/Assignment After trip generation, the projected project study area trips were distributed onto the model network. For modeling — purposes,generated trips are generally produced at the home end and attracted to a destination(usually the employment end). The model balances productions and attractions trips for the whole model and distributes the total trips onto the model roadway network. Comparison with Previous Modeling TJKM used the current 2025 SJCOG model land use and network assumptions for the traffic projections. In the MHMP,the planning horizon year for buildout was 2010.The current SJCOG model buildout year is 2025. The 2010 land uses in the model used to determine MHMP traffic effects are very similar to the 2025 land uses in the current model.For example,the total San Joaquin County land use forecast shows 292,499 dwelling units for 2010 and 332,456 dwelling traits for 2025, a 14%increase.Total forecasted county employment changes from 307,703 jobs in 2010 to 306,109 in 2025,a 1%decrease.When San Joaquin County and the nine-county Bay Area are considered,there is a 4%increase in housing and a 12%increase in jobs between the two forecasted years.In summary, although the target year for the newer model extends 15 more years into the future,the land use projections are consistent,allowing for a reasonable comparison between current model results for 2025 _ project buildout and those generated for the 2010 buildout previously evaluated. The current 2025 regional traffic projections are much higher than the MHMP EIR regional traffic projections. This is because the current SJCOG model includes many regional developments that were not previously included in the SJCOG model.In addition, SJCOG model updates in the past 10 years have made substantial improvements in the accuracy of the model forecasting. It appears that past model forecasting has underestimated the regional traffic demand.Because of the differences between the previous and current projections of regional traffic demand,the estimated with-project cumulative traffic volumes on regional roadways(e.g., freeways)cannot be strictly compared with those of the previous analysis to determine the effects of with-project MHMP buildout relative to those of buildout of the MHMP as approved. The contributions of traffic from the MHMP area are — projected in the current analysis to be essentially the same as evaluated in the MHMP EIR. Therefore, substantial EDAW College Park at Mountain House Spedrfic Plan III Draft EIR — Transportation 4.11-24 San Joaquin County