Sounds like a lack of "sufficient" hand brakes problem?

Another problem with stored cars is that eventually all of the air does eventually bleeds off.......

And, another problem of cars being left unattended, in places with no real security like this, for long periods, is that it allows for all kind of other mischief, like folks releasing the hand brakes.

Runaways like this, due to vandals in several cases for "fun", lazy crewmen, and even dumb ass shippers releasing hand brakes, and failing to reset them, to "move" the car a few feet themselves, happened a few times when I was with the SP.

These incidents resulted in several "runaway" wrecks, including a spectacular one in the A yard where they intentionally ran the runaways into a yard cut. There was also the "great" car "chase" once by Carl Ragoza and crew down on the PE branches. And, worst of all, in the case of the incident at Everett Jennings spur on Sepulveda, resulted in fatalities at a grade crossing in West LA, when the runaway car struck a car full of children,

They're damn lucky that this maybe only damaged some equipment, inconvenienced a lot of folks, but at least didn't hurt anybody/

Safety is of the first importance, obedience to the rules is required.