i haven't read all the content creators guide, but i did look for product mass and also did a search for "tractive" and "pull" and didn't find anything that immediate giving information on how the weight of the load affects the motive power. it obviously does in the game, but i'm wondering about product mass, especially since different creator's versions show unique masses for their product -- "coal", for instance. the ccg says that dry weight is kg per liter -- and that's probably generally the case, though not obviously so in all cases -- in the case of ores, for instance, with their different densities? then too, i'm wondering about the weight of wet loads? -- there's probably not a general system call, "weather condition", but, my ore loads and timber get wet up in the north coast and it would be functional to have a wet load/dry load product choice...?