Industries with their own rollingstock

[dave1905]

Dave, that is alot of cars!
Let's say an industry on a shortline uses plain old everyday boxcars for shipping. They don't have their own cars. When they need empties, do they order them from the serving railroad? And what would happen if the serving railroad had no available boxcars at the moment. Would the railroad order an empty from another railroad?

Two options, which depend on how the shortline was created.
If the shortline was spun off a class one railroad post Staggers, then the lease/purchase agreement probably provided that the selling class one would provide cars for the industries to load. Many variations on this contract, but the jist is the same. In that case the shipper might order cars from the class one or the shipper might order cars from the shortline who in turn orders from the class one.
If the shortline was originally an independent road, then it they have a little more freedom and a little bigger problem. They can ask the line haul roads they connect with for empties since the line haul roads will participate in the revenue. But the line haul roads aren't obligated to give them cars. If cars are tight the line haul road may choose to supply its customers with cars.

Obviously if there are no cars available then the plant doesn't ship anything or ships less until cars come available. Used to happen all the time with boxcars (why IPD boxcars were created), grain hoppers in harvest season (higher capy cars, longer trains, unit trains and tighter management of unit trains pretty much ended that) and gondolas in the late 1970's early 80's.