Travel Demand Model - OKI

OKI/MVRPC Travel Demand Model – Version 6.0Eight truck trip tables were created (SU and MU vehicle types by four time periods, AM-peak, Mid-day,PM-peak and Night). The final truck trip table totals are shown in Table 2-8.Table 2-8. Truck Trip Table TotalsSU TrucksMU TrucksAM Peak 22,849 15,742Mid-day 68,260 51,499PM Peak 30,465 20,013Night 22,131 34,780Daily Total 143,705 122,034The eight resulting tables, two truck types by four time periods, were expressed in terms of floating pointnumbers (fractional values), as produced by TransCAD. To produce integer values as required for inputinto the Tranplan modeling environment, a commonly used procedure known as “bucket rounding” wasused. Bucket rounding proceeds interchange-by-interchange, rounding down to the nearest wholenumber but accumulating the residual fractional values and adding an integer value of one to theinterchange in which the accumulated fractions “tip the bucket” (i.e., cross a threshold of 0.5), then,starting over with the next interchange, accumulating more fractional values until the bucket is onceagain tipped. This procedure was important to use in translating the floating-point number trip tablesproduced by the TransCAD program into the integer-value tables needed by Tranplan because the vastmajority of cell interchanges contained very small fractional values that could have been lost altogetherwithout this step.Truck Model - Base-Year Truck Model Development 28