prevent the mainline from fouling if there is no place for a derailer

[Hazuki]

I have a portable N Scale Layout. I want to add switch stands as details. But before I can do that, I need to understand a bit more about how the railroad prevents the mainline from fouling. Here is a picture of one of my modules:



The first two tracks are the mainline (CTC). As I understand, the turnout for the industry spur is protected by an electric time lock.
Now the part im unsure: I think there should also be a derailer in a distance of min. 50ft. This is not possible here as the next turnout is too close. So how does the prototype prevent the mainline from fouling?

Thanks for clarification.

[GaryHinshaw]

I don't know if there is a unique right answer here, but if it were up to me I would put derailers on the two tracks where a runaway car could potentially reach the main, specifically, the two spurs just off to the left of the photo.   The one on the back track would be past the points of the turnout that is half visible.

Oh, and nice scene!  Let's see some more!   

[C855B]

...

Oh, and nice scene!  Let's see some more!   

You thinkin' what I'm thinkin'? Edison.

[nkalanaga]

Two derails would be my thought as well.  Much easier, and would protect the other track even when one is being switched.

[Hazuki]

Thanks for the inputs and compliments 

At the last convention I only took one shot of the layout . At the moment I am working on the modules and therefore the layout is not in one piece so no better overall pics.



Here are some detail shots which show the switching part of the layout.




And here back to my question:
So you think I should put two derailers left of the yellow circles with arrows? I understand, that this is a protection for parked cars. But doesn't it need a protection while switching is in progress? That's the reason why I thought there must be a locking mechanism for the turnout with the yellow circle. Something like the turnout with the blue circle has (hand-operated turnout with timelock connected to CTC). 

[Stolen Moment]

You can consider the yellow- and blue-circled turnouts as a crossover, always operated in sync.  I have no idea if the prototype did it that way, but it provides the protection you're thinking about.

I don't know if you intended to keep the mainline turnout to the siding when you're switching the tracks to the right of that "crossover", which would invalidate the above, but the dispatcher would welcome the clearing of the mainline ASAP.

[mu26aeh]

I'd think they'd put one on the LPG track as a double safety, prevent the car(s) from getting out of the siding first. 

[Dupesy]

It depends on the purpose of the derail.  If its to keep errant cars from rolling onto the main line, one derail between the two facing-point switches by the large yellow circle is sufficient, so long as it is a bi-directional derail.  There would probably be derails on the LPG tracks, but their purpose would not be to prevent a rollaway but to protect the cars from being coupled to while being unloaded/connections being made or removed.

[signalmaintainer]

Sounds like good advice from the group about the location of derails.

The other switch (circled yellow) is called an "inside switch" and would be equipped with a switch-circuit controller as part of signal system. Any point gap greater than .249" away from the route shown would tumble any cleared mainline signal on the inside main to red. If the crossover is lined and a signal cleared, everything in the CP would tumble to red.

You're correct that the switch circled blue would be equipped with an electric lock (or a leaving signal) controlling and governing movement onto the inside main.

Your single crossover needs a fourth signal, single head, located on the inside main directly across from the double-head signal at the right. What you have now won't provide protect for westbound trains on the inside main in the event the crossover is lined against them or the eastward approach track is occupied. A minor point: one signal bungalow would suffice.

Hope this helps. I worked on many prototype signal systems that are dead-on to what you've modeled. Really well done!

[GaryHinshaw]

I'm out of derailer ideas.  (Are you planning on having working ones?)  But I love what you're doing here.

[dandopinski]

As a former railroader I would place 2 derails inside the gates of the propane facility and 1 derail just clear of the fouling point at the cold storage building. The objective is to prevent the cars, if they start rolling away, to derail them before they foul another track.

[Hazuki]

You can consider the yellow- and blue-circled turnouts as a crossover, always operated in sync.  I have no idea if the prototype did it that way, but it provides the protection you're thinking about.

I don't know if you intended to keep the mainline turnout to the siding when you're switching the tracks to the right of that "crossover", which would invalidate the above, but the dispatcher would welcome the clearing of the mainline ASAP.

I will wire them for being always operated in sync with only one button to push but I don't think it's prototypical as those turnouts in real are hand-operated.
The mainline turnout should only be directing in the spur when the train enters. The concept is, that there can be two train on the main while the switching is done.

[Hazuki]

I'm out of derailer ideas.  (Are you planning on having working ones?)  But I love what you're doing here.

No working ones. I already have switching machines on the main and plan to add switch stands for the hand-operated in the industrial spur.

A friend asked whether the time lock should be installed on the turnout with the yellow circle and whether the switch is synchronized with the main line (which would apparently be the concept here in Switzerland).
I believe that this is not how it is done in North America and that only the turnout to the main line is equipped with the time lock and the electronics for the occupied signal in the CTC. This led to the question of how the main line is protected against fouling. According to a document from UP, the derailer must be 50 feet away from the turnout. Since this is not possible, I am now looking for an alternative.

[Hazuki]

As a former railroader I would place 2 derails inside the gates of the propane facility and 1 derail just clear of the fouling point at the cold storage building. The objective is to prevent the cars, if they start rolling away, to derail them before they foul another track.

I understand that the cars are protected with this setup from rolling away when they are parked.
Doesn't the main line need special protection during switching? In the worst case, a car could be incorrectly coupled and roll away from the locomotive onto the main line if the switch with the yellow circle is not set to LPG.
Or is it entirely the responsibility of the train crew to set the switch away from the main line?

[dandopinski]

The first switch off the main track should always be lined and locked routed away from the main track when not in use, or if the train crew is ordered to clear the main track when they are switching. If the crew has authority to occupy the main track while they are switching, that switch can be left in any position.