---In STMFC@..., <jimbetz@...> wrote :
I will theorize that the destination had a lot to do with whether
the car used was a coal hopper or a gondola. Especially if the
receiver wasn't set up to unload by opening the doors below...
I wholeheartedly agree. Let's not forget, until the end of WWII, the going rate for unskilled labor was about a dollar a day - you could get a lot of coal unloaded for not much dollars. Gravity unloading requires a significant difference in elevation; you either put in a coal trestle, or a pit, with a mechanical conveyor to bring the coal back up where you need it. Neither was particularly cheap, compared to that dollar a day labor. Of course, wage inflation during the war and certainly in the decade afterwards changed that equation, and then hoppers steadily replaced gondolas as the car of choice for coal.
I am reminded of a thirties era aerial photo I have of the Fox Head Brewery in Waukesha, WI (home of "Fox Head 400" beer). This was by no means a small brewery - it occupied a good city block, wedged into the angle between the junction of two railroads; C&NW, and the Soo Line. The shipping doors are on the C&NW, across the tracks from their depot, and there are seven or eight reefers spotted for loading. Not a small operation at all.
The boiler house is on the other side of the complex, along a spur off the Soo. Spotted alongside is a gon half filled with coal - half filled as in only one end is empty. In the middle of the gon, barely visible, is a man, diligently shoveling his way from one end of the car to the other, throwing the coal into the boiler house through an opening in the wall. There is absolutely no evidence of any dump pit.
For a long time, labor was cheaper than mechanization, and a whole army of men fed their families by trudging off to do manual labor each day.