Two guys, a bunch of computers, a watchtower, and hundreds of freight cars, coupling, uncoupling, and moving around by themselves.
I did some work with Amazon Fresh a few months back.
They just bought a company, Kiva maybe?
Their little robots pick food orders right off warehouse shelves and deliver them to the correct trucks.
Yes, and we have a partly remote controlled, partly robotic rail system outside the yards. But there are still engineers and conductors on board.