Use of a simulation model to evaluate wheat segregation strategies for country elevators

Simulation models for three different country elevator configurations were created to assess the impact of segregating wheat into two different quality categories on queue length and time in the system compared to a no-segregation strategy. Assumptions used to develop the three configurations resulted from an infrastructure characterization of the grain receiving system(s) and scale ticket summary reports. The model configurations varied based on sampling location, number of drives and receiving pits, number and capacity of bucket elevators, truck sizes, and storage capacity. Time data revealed that locating the sampling station ahead of the scale is essential when segregating grain into two quality categories. The model representing country elevators with two legs (bucket elevators) and two drives appeared best suited for segregating grain. A historical verification test was performed using the 10 most active hours of the day for three commercial elevators and comparing these data with model output. A degenerative test of model validation was performed by evaluating the tons received with the percent small trucks and a sensitivity analysis was performed looking at the relationship between the average time a truck spends in the system and truck size. The results generated by this model conformed to expectations during the verification and validation process and appeared consistent with the observations of country elevators made by the researchers. The models will provide a useful tool for future economic analysis of segregation activities at country elevators.