Optimizing haul unit size and number based on loading facility characteristics

Determining the optimum size and number of haul units for an earthmoving project is a task of critical importance. Past approaches fail to recognize critical characteristics of the loading facility which ultimately impact on the overall system production. Regardless of the size or number of haul units used in an earthmoving project, the hauling system's total production can never exceed the productivity of the loading facility. This paper presents an improved model for optimizing haul unit size and number based on a function of loading facility characteristics as modeled by a load growth curve. The model relies on the derivation of a cost index number (CIN) to determine the optimum size and number of haul units for the given loading facility. Detailed discussions of the impact of rounding off haul unit number are also presented to highlight the importance of this decision. The paper concludes that the use of this model provides a means to design the construction equipment fleet for a wide range of material moving projects.