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I would like to place signals in realistic locations on my lower level main line and would appreciate some advice. I want to use these Atlas signals...

Atlas O 6930 3 Rail Realistic Road Signal

Here is my lower level...

Lower Level v2

To explain the plan.....All track in the grey areas will be concealed under the second level and will not be visible.  As you can see most of the lower level is out of sight, I did this to hide the O96 reverse loops.  For now I just need to place signals on the tan benchwork. At the rate I am going I will build the upper level sometime in 2035 and will ask for help with them then! I used R-R Track software to design the layout. I attached the plan if you have that app.

thanks for the help!



Last edited by T4TT
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Sorry that you did not get any replies to this.  Presumably you are looking for prototype signal placement and I am not qualified to help either.  However, I find you layout very interesting and would like to hear the background on it and maybe see the upper layers.  Perhaps this is a different thread.  If you are so inclined, interested in your plans.


The idea with signals is to indicate if track ahead is clear. Therefore, if you want to show that a siding is clear for a train to enter, for example, generally you would place a signal prior to the siding switch or turnout. The signal would then be wired to IR sensors placed in the siding or an isolated track section within the siding that would trigger the signal to change color depending on whether the siding is occupied. Most signals will come with wiring instruction or there are many references on the forum.

I love signals and am 3/4 done installing them on my layout.  What is the main thing that you want your signals to do?  By that I mean, do you just want them to change when a train passes, indicate whether the track is clear ahead, or also show which way a switch is thrown?  Do you want to be able to run trains by your engineers following the signals like a real railroad?  Do you have your layout divided into blocks?

The answers to these questions will help determine where you put your signals and which signals you use.  Obviously it can be as simple or as complicated as you want.  It sounds like you may just want signals at the beginning of each block that tells you whether the block of track ahead is clear.  If so, just determine your blocks and put a signal at the start of each one.  Do you want single direction signals or bi-directional signals?  If you want bi-directional double everything for the other direction.

If you  want to show switch positions (straight or diverting)  with occupancy, you will need to add signal heads and additional boards and wiring.

It can be as simple or complex as you want and can afford.

Good luck, Art

Real railroad practice dictates that signals are placed to control traffic at "control points." What's a control point? A switch.

Signals placed at crossovers or sidings are called "Absolute Signals" because they ABSOLUTELY control the traffic movement at that location. You cannot pass an Absolute Signal without specific permission from the dispatcher.

Signals placed along the main line not located at switches are called "Intermediate Signals." Place an intermediate signal before the siding, at a distance of a scale half mile or so. If you don't have room for that, just put it a train length before the Absolute Signal.

There is just so much information available about railroad signaling, I would just recommend you search the internet for whatever your interests are.  E.g., if you are modeling a specific railroad (PRR, UP, NYC, CB&Q, etc.), just search for that railroad's signaling equipment and practices.  There are also quite a few websites that can suggest placement scenarios and signal types to use in those scenarios, depending on how "realistic" you want to be.

Personally, the hardest part of signaling is determining what you want to do, finding the proper equipment at an affordable price, and then making it all work as planned.  But don't be deterred; there are lots of options available.


There are a number of resources available to help you.  Since you are using the Atlas/Custom Signals signals you are looking to have an operating system.  Here are a couple of books about signaling.  The first is written expressly for model railroading while the latter describes use on railroads.

Guide to Signals & Interlockings: Design and Build a Working System for Your Layout

Railroad Signaling

Here's a link to a clinic run by the NMRA Signals 1.01 by Mike Burgett  The NMRA has a lot of information on signaling.


Last edited by Rich Melvin

Maybe you can find a location were you need a signal on your layout.  An example is my layout has a hidden track and I made a signal to show me when the track is occupied with three lights that show the position of the trains on the hidden track.  This has stopped several possible wrecks.  Such a location makes the signal important verses coping a real track location that will not improve the operation of your layout.

You might want to make some kind of signal system to tell you where the trains on your whole lower level are.  Maybe a camera system using in expensive security system cameras.  I use such a camera on a flat car to transmit layout moving pictures to a 55 inch flat screen TV.


Last edited by Choo Choo Charlie

I am grateful for the feedback. My goal is to use the signals is to indicate if the track ahead is clear. I need to work out how far back to place the signal from the block. A train length is pretty long but that will be my goal. Here are the 5 blocks (purple track) I think I need to signal....

Grand Circle RR Blocks

Many of the blocks have switches in the run. I am using DZ2500s on Atlas switches. All switches are wired for the non-derailing function. I prefer to use the isolated track method of wiring as opposed to IR sensors. So I think I have to use the inside rail to trigger the lights since those two rails are already isolated (I cut the jumper for those rails on the underside of the switches). Anyone wire an Atlas switch for such an application?

@ogaugenut here is the upper level to be completed sometime in 2040 ha!...

Grand Circle RR Upper Level


Images (2)
  • Grand Circle RR Blocks
  • Grand Circle RR Upper Level
Last edited by T4TT

There is an interesting distinction here.  Some set up signals that are very much intended to accurately reflect and model real train signals.  Others set up signals to communicate to the model train operator the status of parts of the layout to avoid accidents.  These layout signals may or may not represent real railroad signals.  I have built many floor layouts in my life, some across multiple rooms.  I have used signals to indicate the status of switches and blocks in the other room and they probably don’t replicate real railroad signals.  There may be a third type of toy layout where signals are placed randomly for decoration and have no relation to real or layout signals.

T4TT that is a very ambitious layout build.

OK, now I have some idea of what you are trying to do.  But, let's analyze your proposed signal locations.

You have 2 signals on the right, one apparently facing each direction on your purple main line.  A train stopped at one of those signals is prevented from entering the return loop on the right, presumably meaning another train is already in there.  However, once the "lead" train completes the reverse loop, it heads back toward the stopped "following" train, but I see no where for either train to get around the other?  Now, if you were to put that signal near the industrial siding, you could force that "following" train into the siding so that the "lead" train could complete the loop and then get past the "following" train sitting in the siding.  Only problem is the "following" train would have to completely back out of that siding and then proceed through the reverse loop.

A similar problem exists with the second signal on the right side.  Is your "following" train going to stop there and wait (assuming all trains are running the same direction)?  If so, for how long?  And, what happens if that signal is red because an opposing direction train is approaching?

These "issues" fairly accurately explain why signals are usually found near switches and crossings, being meant to avoid collisions.  They can, however, be used to prevent "rear end" collisions IF the trains are only moving in the same direction on a long piece of track (hard to do when two reversing loops are involved).


I have bought and read till they are tattered, many a track planning book for the past 63 years dreaming of that perfect layout, and I have learned a few things along the way.  In your case, your main line is the yard lead to both staging yards, so if you plan on letting 'em rip on the main, you are going to have some issues.  Also, none of your yards have engine escapes and all are single ended.  I would try to get that yard next to the round house to be double ended, and get some parallel tracks on the ends so you can let the express go by without having to wait for the red signal while the yard is being switched.  Consider an interchange track somewhere too, that brings many opportunities for a reason  to have foreign power on your empire.


All of your suggestions are both excellent and ideas I have toyed with. I have 100's of iterations of this track plan! I have tried to put a junction in the lower level but I just can't find the space for it. I am not crazy about all the yard tracks being deadenders but again this design is a series of compromises.  I wanted a dedicated switch engine pocket, but I could not find the room so I plan on parking the switcher in front of the car repair shop. From there it can pick up trains dropped from either entry point to the service peninsula. The lower level main line is primarily hidden under what will eventually be the upper level. The switch at the tunnel (inside the yellow rectangle) essentially essentially creates two yard lead to the icing platform that will often be red due to reefers get iced but the other lead, closet to the wall should generally be green. If you see ways to incorporate junction/interchange or making the yard double-ended please let me know.

thanks very much for your insights!

yard lead


Images (1)
  • yard lead

@Rich Melvin

thank you Rich. I think I have Yard Lead Tracks coming to the yard from both directions. Here is how I think I will move cars to and from the yard. Please let me know if I have it wrong.

Grand Circle RR Lower Level v4

The lower level main line  (blue track) is really just two reverse loops. The majority of the lower level main line will eventually be hidden under the upper level to hide the reversals and maintain a sense of realism.  The green track will be the lead track for trains coming from reverse loop 1. The pink track will be the lead track for trains coming from reverse loop 2. Both leads permit the train on the main line to run uninterrupted from reverse loops 1 and 2. Both leads are longer than the longest yard track and both allow the engine to get to the TT. Although the engine must back onto the TT from reverse loop 2. Am I missing something? The screen grab is very blurry so I hope you can make it out.

Reverse loop 1 will also be used to reverse  trains from the upper level. There will be a switch at the top left of diagram and long downhill track running parallel to the wall to allow trains traveling in a counter clockwise direction to access the loop. There will be a switch in the closet under the steps to  allow trains traveling in a clockwise direction to access reverse loop 1 as well.

The yard on the upper level is for a passenger station. I will not be building passenger trains and those tracks are just for staging trains in front of the the station so I did not build a yard lead track there.

The yard at the bottom of the diagram is off the layout in a storage closet and is just there to park trains. Same is true for the yard at the bottom right of the diagram. That yard too is off the layout and is for parking trains.

I hope my explanation makes sense. If anyone has any advice/feedback please share. As is the case with all layout plans, I had to make compromises due to space constraints and the desire to maintain realism.


Images (1)
  • Grand Circle RR Lower Level v4
Last edited by T4TT

My take is a little different.  At what locations are the signal aspects going to be visible to you?  At what locations are the signal aspects going to be readily noticeable to casual viewers of the layout?  That should be your starting point for determining where to put your operating signals.  If a signal is at a location that would be prototypically correct, but its aspects are not easy to see by an operator or casual viewer, it might as well be a dummy.  One reason I like semaphores is that you can tell what the signal is indicating even if the lights are not visible.

It is only once you have determined the locations where operating signals adds something visually to your layout's enjoyment or operation that you start asking "Is there a prototypical reason why a signal would be located there?  And if so what type of signal would be used?"

Last edited by Bill N

If you don't have a switch lead, you have to use the mainline. That means the dispatcher has to stop train traffic which usually will not happen, but if and when it does that also means the dispatcher is not very happy with YOU! lol "How much longer til you're in the clear? I need you clear in 5 minutes!" Copy that, no problem......... 20 minutes later

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