A coal train with 25 cars arrives at a tipple. The basic industry track takes control. The train then proceeds through the tipple and only the first 7 cars are loaded. The remainder go through but no coal is deposited. I assume that the tipple exhausted its storage of coal. My question then becomes what is the process to build a long train of loaded coal cars. One tactic may be to send out one or more short coal trains, return to the yard and added each train of loaded cars to the existing long train. Then deliver the coal. That is only a guess. In the real world how would a 50 car train be assembled fully loaded with coal?