Travel Demand Model - OKI

OKI/MVRPC Travel Demand Model – Version 6.0The growth factors for each TAZ were then multiplied times the row and column totals of the daily baseyear truck tables to obtain expected row and column totals for the future year, as follows:2030 ForecastedP/As=Base-YearEstimated P/As×2030 PreliminaryTrip Ends1995 PreliminaryTrip EndsIt is important to remember that the row and column totals of the base-year truck tables that wereproduced through the synthetic matrix estimation process are substantially different than what theproductions and attractions would be by simply applying the coefficients. In the cases of five TAZs thathad no population or employment in the base year but were projected to have employment andhouseholds in 2030, the trip generation rates were used directly to project future trip ends, becausegrowth factors could not be applied.4.1.4 Apply two-dimensional matrix balancingA two-dimensional matrix balancing procedure (also known as the Fratar or “growth factor” method) wasused to estimate forecast-year truck trip table interchange values.Details: The method uses the base-year trip table as a starting point, a “seed matrix” and the 2030forecasted productions and attractions as row and column target values. The two-dimensional balancingmethod is an iterative procedure of re-factoring the rows and columns of the base table, until aconvergence is reached in which the target values for row and column totals are met. This is doneseparately for SU and MU trucks.The base year tables used were the TAZ-level daily truck trips, as produced by the TransCAD program.For the fives zones that had zero truck trips in the base year, the corresponding rows and columns in thebase-year table were seeded with values of 0.00001. This seeding was necessary in order for thebalancing process to allocate trips to these zones.4.1.5 Allocate the forecast daily truck trips to analysis time periodsThe time-of-day factors developed to allocate SU and MU trucks in the base year model were also appliedto the 2030 daily truck trip tables to allocate trips to each of the four assignment periods and convertedto integer format for input into Tranplan. These procedures are described in detail in Section 2.5.2,above.4.2 Summary of Forecast ResultsThe forecasted growth in daily truck trips for 1995 and 2030 are shown in Table 4.3, below, expressed ascounty-to-county flows. In total, 480,000 daily truck trips are forecast for 2030 in the combined OKI-MVRPC region, including substantial growth at the external stations. This translates to a region-wideincrease of 81 percent over the 35-year period, an average annual growth rate of 2.3 percent per year.Truck Model - Truck Trip Table Forecasting Procedures 50