SIMULATION VERIFIES QUEUING PROGRAM FOR SELECTING LOADER-TRUCK FLEETS

Proper equipment selection can yield substantial savings in ti- and cost. MicroCYCLONE simulation package is used to verify the FLEET queuing program. FLEET models multiloader-truck systems using exponential distribution at steady state. A few FLEET assumptions are redefined to closely model real-world construction processes. Graphical solutions illustrate effects of the cycle-time modeling and transient state on multiloader-truck fleet selection. FLEET is shown to be an accurate model of the steady-state, multiloader-truck process if exponential distribution did accurately fit load- and travel-time distributions. But, erlang of beta distribution more closely fits actual load and travel times in construction. Modeling load and travel times of loader-truck fleets with exponential, instead of beta, distribution results in underestimation of production and overestimation of unit cost by 4-7%. Simulation results of a more accurate model that uses beta distribution and considers transient state, in addition to steady state, indicate that multiloader-truck fleets may experience a 4-5% production increase and unit-cost decrease compared to FLEET results.