A westbound freight train out Marquette, IA, bound for Mason City, IA, has 12 SD40-2's in consist. Eastbound trains out of Mason City require extra power to get over the grades on the roller coaster Mason City Sub. Then at Marquette the train run south along the fairly flat river grade that requires less units, so eastbound trains usually setout power at Marquette to be moved back to Mason City. When traffic gets imbalanced, sometime big power moves like this can happen. Here the train only has 4-5 units online to move back to Mason, the rest are along for the ride.