4.2. Time model results
Fig. 2 and Fig. 4 display the results of the time model described in Section 4.1. Fig. 2 shows that shuttle service is faster than conventional service when the rail transport demand rate is greater than 350 tons per day – a relatively low rate. As the demand rate increases to values greater than 2500 tons per day, shuttle train service transports grain nearly 50% (12 days vs. 6 days) faster than conventional service. Fig. 3 displays the total time for a demand rate of 1500 tons per day broken down by trucking, elevator storage, and rail transport time. Shuttle trains are significantly faster at moderate-high demand rates because they are able to bypass classification yards. The reason why conventional service is comparable/slightly faster at low demand levels is that it takes a long time to consolidate enough grain at a terminal elevator to fill an entire 110-railcar shuttle train; therefore, the average grain spends a long time in storage at a terminal elevator. The main takeaway from the time model presented in Section 4 is that at moderate and high demand levels, the total time it takes for grain to travel from the farm to the export elevator is significantly lower when it travels via shuttle train service.