Steam What Are These "derail" Devices At The Entry Of Some Sidings ?

I understand that they act as a kind of signal. I can drive into the siding, but how do I get out ?? The dispatcher says "Denied, set switches " .

I did that and the switch was set correctly, I come from the left and the switch was set left.
So a waited for half an hour, but the signal didn't go to green automaticly.

Then I set the switch to the right, which was not my path and I could pass ! ?

Can anyone explain what kind of logic this is ? Is this like in real life ?

 

You must clear a path beyond the next signal after the derail, in order to get it to work correctly. Sometimes, however, you can manipulate objects to get it to work, although this is probably a bug more than anything else. There's much more discussion about derails in the freight hauler feedback thread:

https://forums.dovetailgames.com/threads/freight-hauler-feedback-thread.99414/

 

First I had a path to a point behind the derail, that didn't work. Then I tried your advice and made a path behind the next signal, 8000 ft away, that didn't work either. And also setting the switch to the siding to the other position did not work.

 

The only other thing I can think of is that, if you cleared a path beyond the next signal, perhaps it needs to be further than that, to cover signals in both directions. Also, even if you have a path, you won't get cleared over the derail if there is another train coming. You would still have to wait for that train. Sorry I know it can be frustrating.

Another method to try, if you are so inclined, is to spawn a car or loco so that it straddles the derail. Then you can couple to that and leave. Warning: this may cause unsolvable pathing errors later on.