has anyone ever loaded empty coal cars with snow when there is no room for the snow and hauled somewhere else
A number of times. Not always with the desired results.
After the Blizzard of '77 in Buffalo, NY, they loaded hoppers with snow and sent them south. Unfortunately, the cold followed the hoppers and the snow didn’t melt… Presented something of a problem when it came time to load them with coal again…
In 1967, Rock Island loaded gondolas with snow after cleaning out Burr Oak and South Chicago yards and shipped them to Texas.