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MODELING METHODOLOGY A computerized traffic model was utilized to calculate the trip generation of the various future land developments within the study area, and also to assign this traffic onto the street network. Standard I.T.E. trip generation rates were used in this model, and are documented in Table II. These rates are based on data in Trip Generation, Third Edition, Institute of Transportation Engineers (n-q. In addition to the estimated future land use quantities within the study area, a very large region surrounding the study area was also incorporated into the model as cordon stations. These cordon stations or "super-zones" include areas such as Tracy, Manteca, Lodi, and other areas of San Joaquin County. These cordon stations are also the stations through which the "through" traffic passes. Through traffic is defined as vehicle trips that do not have an origin or destination within the study area, but rather are just passing all the way through. These through trips were determined from the current growth rate on the freeways, and on the streets of Stockton and San Joaquin County. This particular traffic model used for this analysis was a p.m. peak hour model, which simulated future traffic flows on the street network for this peak time period. The p.m. peak hour was considered to be the critical time period for the study area, largely due to the many office and industrial uses planned for the study area. Typically, the p.m. peak hour is the critical time period on most roadways. During the p.m. peak hour, two types of vehicle trips predominate: 50 to 60 percent are trips to and from work, and 30 percent are non-work trips to or from commercial centers. Other home- based (social) trips account for 20 percent of total daily traffic, but only 10 percent of peak hour traffic; non-home based trips, normally 15 percent of off-peak travel, account for only 5 percent of peak hour trips. This traffic model is set up to reflect these parameters. In calculating the distribution of traffic within and through the study area, several other parameters needed to be provided to develop the traffic model. The internal/external distributional split was determined for trips or productions generated by residential uses. To accomplish this, it was necessary to divide both the production and attraction trips into three trip categories of home-work, home-other, and non-home based. Data on percentages of production trips in each of the home- based trip categories were derived from the Transportation and Traffic Engineers Handbook, ITE. A capacity restraint was incorporated into the design of the model to assign the future traffic to the street network in stages or increments. Four iterations of assignment were used, with each assignment adding yet more traffic to the streets, until it was all assigned. In this iterative process, as certain streets approached capacity, the model then reassigned a portion of the remaining traffic to less crowded 10