Industries with their own rollingstock

[Brakie]

So where does the industry keep the empties?

And when a customer of the industry orders a load, I guess as long as the industries own cars are available, they would use those for shipping the load?

What if all the industry's cars were in use? Where would the needed empties come from?

Would the industry's cars typically be in captive service?

Those cars are usually held in the closest outlaying yard in some small city or town near the industry.

Privately owned cars is used in captive service.However,that doesn't always mean unit train size shipments as some(say grain) may go to a milling company or perhaps end up as bagged feed for live stock...