Coal Hoppers, also known as coal stages or coaling stations are elevated structures located throughout Sodor and abroad. They contain coal to refill the coal supplies of steam engines.These hoppers feed ball mills which in turn feed the pulverized coal to the boilers. There will be at least one hopper for each boiler. Typically there are two boilers per unit. Challenges:Coal hoppers and silos storing the pre-pulverized coal are large and have very dusty environmental conditions.