I'm fighting a common problem on our club layout that I'm having difficulties with in signal design: there are quite a few places where we have facing turnouts that are directly opposed to each other. This gives us only about an inch between each set of facing points.My problem comes in when I want to signal these interlocks. On the prototype, the areas we are modeling would have had a lot more spacing in between these control points, so placing another signal would just be dead obvious. When we compress for a model it's a different story. With the switch points so close, I'm really torn on putting a signal right in between those switch points. If I place a signal it seems I would have 2 problems:- Trains would stop while sitting on the switch points when they have to stop at the signal.- Trains coming from the diverging route have a hard time seeing the signal.The big downside that I see with eliminating that signal is that there are more spots that really require 3 head signals so that you can line movements from far sidings or second mainlines into yards or other branching track.For all the railroad gurus: what's the preferred alignment? I'm sure that the prototype at some point had similar track arrangements because of lack of land, but I'm not sure if it's on mainline and if they would have to back the speeds WAY back due to the special trackwork.Thanks in advance!
A photo or diagram would be very helpful.
How about a signal bridge with heads on both sides?
Apologies for the bad curve drawing, but here's the general track section in question:This is one end of a dogbone configuration folded into the layout ( this is to simulate long-haul passenger operations: the inside tracks and crossover of the dogdone is where our staging yards are).The left side curved track goes through the backdrop and engages the main with a #6 turnout ( we wanted #8 but were constrained by benchwork and clearance on the other side of the backdrop/wall ). The RH crossover and the turnout lead heading to the dogbone crossing spot are both #8 curved turnouts.I have 2 problem areas:- Trains sitting in the passing siding waiting to enter the main where their destination is to curve around in the dogbone- Trains traveling east on the main.I'm not really concerned about not having room to actually place the signal ( I can always put it on a bridge ), it's about the practicality of stopping trains inside of the interlock. What seems "natural", at least to me, is that it would never make sense to have trains pull up to swtiches inside this interlocking configuration, since there really isn't even room to hold a single switcher in the trackwork, but that then creates a problem for head configuration entering the interlock, and I don't good reference on how a prototype signal deisgner would handle this.....Also, since we are modeling the West, I am assuming route signal rules ( ATSF, UP, SP, T&P ) along the entire layout.
wouldn't signals be outside the interlock, the section of track including all the switches?
on the right side, there could be a bridge with 4 signals, one for each track (x-over, staging, black & orange)
on the bottom, there could be a single eastbound signal on the passing (orange) track ahead of the crossover (red)
there could be a single eastbound signal on the mainline track before the trailing leftmost switch
greg - Philadelphia & Reading / Reading
Yes, Greg is correct.
Sheldon
Three bridges/groups of masts:
1. At the bottom at the clearance point of the dogbone across the dogbone, main, siding.
2. Across the middle at the right end of the red crossover, crossing the siding, main and dogbone.
3. At the clearance point of the staging switch, covering the staging lead and main.
Why would you need 3 head signals, the same indications can be made with 2 head signals?
Dave H. Painted side goes up. My website : wnbranch.com
Well, yes, I don't think you'd ever see a situation where trains stopped on a switch by a signal if it could be avoided. Your main signals would be far enough back to keep trains out of the whole conglomeration of switches if they have to stop. Think of the interlocking area as kind of like a limited-access controlled zone, where you only want the signals to allow one train at a time to enter.
On the main, where on the diagram you have the word "MAIN", you'd want to have a signal somewhere between where the word "MAIN" is and the first switch, so trains stop short of all the switches (if it has to stop).
On what I take is the other end of the main, the black track going up towards the word "STAGING", you'd want to have a signal between the word "STAGING" and where the staging blue track joins the main, so again trains that have to stop are stopped short of the entire interlocking switch area.
The passing track could have dwarf signals on each side of where the passing track connects to the mainline. In fact, within the interlocking, you could have several dwarf signals just to indicate how those switches are set. Not exactly prototypical, but would work to tell someone running a train how the track is set.
I like Dave's solution. The interlocking can be as simple or as complicated as you want.
Before they changed track and signal arrangements at one of the control points that controlled entrance/exit to Council Bluffs yard, you could cross over from main one to main two, goverened by a signal on a signal bridge and encounter a dwarf/pot signal on main two within the same control point that governed a switch from main 2 into the yard. There were other routes in and out of the yard through that control point that had signals within the CP because it allowed a couple of routes to be used at the same time.
Since simplified, there are only signals at the entrance to the CP and some of the routes that once had powered switches now have hand throws.
Jeff
I tend to agree with only dealing with the home signals due to the compactness of the interlock. The primary feature of our club layout is Tower 55 ( we're in the Fort Worth area ) and I've been studying that interlock in detail, and the signal arrangement is pretty crazy, with dwarf signals all littered around inside the interlocking limits, but from what I can tell the primary reason for all the signals is because they would get especially switchers to hold inside of some of the intermediary switchwork while they were routing other traffic around, so it made sense to have all of these independent sections since you could actually hold trains there.My question about signal heads really revolves around the fact that, if I place home signals at both the eastbound main interlock entrance and the dogbone entrance, I have several possible places where I exit the interlock, and I don't have intermediate signals to tell the engineer which route out of the interlock I'm headed out of. Remember, I'm using route signaling rules common in the west, so "classifying" the exit routes by speed isn't really what I'm after.The thing that especially trips up conversations with my fellow members who are old school railroaders would be the overloading of diverging clear conditions. On the eastbound main we have 3 different exit points: the mainline outside the dogbone; the mainline inside the dogbone, and; the passing siding. A diverging clear aspect on the eastbound signal could indicate any of those 3 exit points, is that a fine aspect configuration? The old skool railroad guys I think don't see it that way just because most of the interlock configurations they ran through left room where you didn't do that much overloading because you held trains in intermediary sections.Is that kind of overloading kosher or anywhere near prototypical?
avaspellIs that kind of overloading kosher or anywhere near prototypical?
I have to agree - too much crammed into too little space.
Wayne
One thing to remember about Tower 55 is that originally was where the TP/MP, MKT, SP, ATSF and FWD all crossed each other. It's not just one railroad, it's not just a pair of mains. There had to be connections from many of the different railroads to other railroads. It is not a simple interlocking.
It had it's own operator until after the mergers then we moved into the HDC. They did huge upgrading and realignment a decade or so ago. That changed many of the connections and eliminated some of the redundant ones.
One of the best maps of Tower 55 was in Trains magazine many years ago even the railroad guys used that map for a quick reference.
avaspellMy question about signal heads really revolves around the fact that, if I place home signals at both the eastbound main interlock entrance and the dogbone entrance, I have several possible places where I exit the interlock, and I don't have intermediate signals to tell the engineer which route out of the interlock I'm headed out of.
avaspellThe thing that especially trips up conversations with my fellow members who are old school railroaders would be the overloading of diverging clear conditions. On the eastbound main we have 3 different exit points: the mainline outside the dogbone; the mainline inside the dogbone, and; the passing siding. A diverging clear aspect on the eastbound signal could indicate any of those 3 exit points, is that a fine aspect configuration?
How do you "overload" a signal indication? So a diverging clear could indicate multiple exits? As long as all of the exit routes have a block signal system on them for at least 2 blocks beyond the interlocking and the exits are on diverging routes, and all those routes are clear for those two blocks, what's the problem?
Tell me about it: I'm doing very careful modeling of all the signals in it. :)BTW: If you have or know of any east <-> west pictures with signal details dated from the 50's or 60's ( there were a lot of signaling changes especially for the dwarfs in the 80's ), I would be eternally grateful. North and South was very photogenic, but east west is rare. :)
dehusmanD
Since model railroading sometimes creates track situations that would be unlikely in the real world, it may not always be possible to set up a truly prototype signalling system for it.
Perhaps just get some three-head signals and assign a meaning to each aspect. So say green-over-red-over-red means the train is routed onto track A, yellow-red-red means track B, red-green-red means track C, etc.
The purpose of signals is to impart information. As long as everyone understands what the signals mean, then it should be OK, even if it's not exactly what the prototype would do.
wjstixPerhaps just get some three-head signals and assign a meaning to each aspect. So say green-over-red-over-red means the train is routed onto track A, yellow-red-red means track B, red-green-red means track C, etc. The purpose of signals is to impart information. As long as everyone understands what the signals mean, then it should be OK, even if it's not exactly what the prototype would do
The purpose of signals is to impart information. As long as everyone understands what the signals mean, then it should be OK, even if it's not exactly what the prototype would do
Except now you need to provide a secret decoder ring to your crews to understand the complicated meaning of these signals that only exist on your layout.
Chris van der Heide
My Algoma Central Railway Modeling Blog
avaspellBTW: If you have or know of any east west pictures with signal details dated from the 50's or 60's ( there were a lot of signaling changes especially for the dwarfs in the 80's ), I would be eternally grateful. North and South was very photogenic, but east west is rare. :)
Don't have any idea what you are talking about N-S vs E-W. Track direction makes no difference in signalling.
avaspellLogically, there didn't look to be a problem, but I'm very new at studying how the prototype does these things, so that's why I ask the wise young folks over here to double-check me.
We can't double check anything unless we can see what track arrangement you have and what rules you are using.
avaspellOn the eastbound main we have 3 different exit points: the mainline outside the dogbone; the mainline inside the dogbone, and; the passing siding. A diverging clear aspect on the eastbound signal could indicate any of those 3 exit points, is that a fine aspect configuration?
Yes. The signal indications are just "clear" or "diverging". "Diverging" doesn't really indicate which of the 3, 4, 5, or 50 possible routes the train can take. Large passenger terminals with complicated throat trackage don't have 14 head signals to distinguish all the different routes.
cv_acr wjstix Perhaps just get some three-head signals and assign a meaning to each aspect. So say green-over-red-over-red means the train is routed onto track A, yellow-red-red means track B, red-green-red means track C, etc. The purpose of signals is to impart information. As long as everyone understands what the signals mean, then it should be OK, even if it's not exactly what the prototype would do Except now you need to provide a secret decoder ring to your crews to understand the complicated meaning of these signals that only exist on your layout.
wjstix Perhaps just get some three-head signals and assign a meaning to each aspect. So say green-over-red-over-red means the train is routed onto track A, yellow-red-red means track B, red-green-red means track C, etc. The purpose of signals is to impart information. As long as everyone understands what the signals mean, then it should be OK, even if it's not exactly what the prototype would do
On a model railroad, you could post a "cheat sheet" next to the interlocking plant. On real railroads, railroads have a book they carry with them with rules, lists of special circumstances, etc. so it's not that unrealistic. Plus, the signal I described would only have six indications - seven if you count 'all red' meaning stop. I don't think it would take that long for regular operators to get to know what it means.
That's assuming the OPs wish to have one signal that gives every possible indication of how the track is set. If it were me, I would do a simpler two-head signal at each entrance to the interlocking and use dwarfs or a simple red-green signal indicator to show how each turnout is set.