Do empty cars in middle of train create a risk of derailment?

[TucsonRailFan]

If there are several empty cars together in the middle of a train, and heavily loaded cars behind these empties, does this create the risk of a derailment when pulling the train through sharp uphill curves? Or is the coupling system/hardware low enough to prevent this?

[setxrailfan]

Not necessarily. The only thing I can think of is slack action. It can run in from the rear. I currently am working a yard job. Breaking down trains and making other trains out of them. We are alerted to "pop-up" hazards if one or more cars may pose a risk of their placement in the train.

[TucsonRailFan]

Originally Posted by setxrailfan

Not necessarily. The only thing I can think of is slack action. It can run in from the rear. I currently am working a yard job. Breaking down trains and making other trains out of them. We are alerted to "pop-up" hazards if one or more cars may pose a risk of their placement in the train.

Thanks. Sorry, but can you explain to a novice what a "pop-up" hazard is? An example or two?

BTW, sounds like a cool job!

[setxrailfan]

No problem. For us a pop-up is usually a short tank car but can be any kind of car that is lighter than the loaded cars in front and behind it. We have lot's of small hills that can play havoc with the slack action running in and out if the engineer is in-experienced on that run.