Signals and systems and where to put them

Model Railroader General Discussion (Model Railroader)
1

Over the last several years I’ve been making and also buying signals for the layout. I even bought several semaphore signals. Now the question is

-Where to put them

how to make them work (tortoise)

how to wire them to work in conjuction with turnouts

etc…

I have some idea of how to do this but, I’d really like to to understand signalling fully and in simple terms before i start drilling and laying wire that will be hard to get at once the scenery starts (cliffs, trees, rivers)

Is there a go-to site or other resource I should look at.

Fergie

2

RMC ran a series of articles by Bruce Chubb recently on signaling.

Baring that, there are several prototype signaling books on the market, one of which, that I have, and that gives a good overview and simple, clear explanations, is simply called Railroad signaling, by Brian Solomon.

Model wise, are you going with block signals, or, the hobbiest stand-by, route signaling at turnouts? This will determine if the book I referenced will be of any help.

And, there is a basis on a local shortline near me that makes route signaling prototypical for model railroaders… The only signals they have is at the ends of sidings, and at interchange and interlocking/crossing locations. The rest of the line is dark territory.

3

I was planning on using both. Yes I’m a sucker for punishment!

4

Prototype signaling is very complex…that said, it can be simplified for model use and still look very realistic.

Signals at turnouts do not just indicate tunout position, they also respond to train detection like a block signal. They are called “interlocking signals”, so they are both a block signal and a route signal in one.

Seldom is the mainline run of a model railroad long enough to justify or require true block signals. Very effective model signals can be created using just signals at the interlockings (turnouts), since these locations are generally block boundries also.

Might be better to read some of the older info, look up Bruce Chubb and Ed Ravenscroft articles from the 70’s in MR to better understand how to adapt signaling to a model layout, then use whatever products or technology you like to build the system.

Sheldon

5

Because of my almost 50 year career in communications and electronics I was able to build up my own signaling system. The basic system uses Robert Paisley circuits. I originally went with current detection because my layout was still a DC only operation. When I cutover to DCC I found optical detection better fit my layout configuration. Any block detector will drive the Paisley Block Signaling Controller.

As Sheldon states a block signaling system combined with turnout position can be complex. Using the Paisley signal controller it turned out very easy to come close to a prototype operation. I simply used latching relays on my Atlas turnout motors and the contacts on the Tortoise machines to preempt the controller detection inputs.

I have an old post on my blog of my signaling system. I haven’t updated the post for the optical detection, the rest of the post is correct. The system has been in and operating for close to ten years.

6

[:-^]

REally great to see you back in here Fergie. I was wondering if they were keeping you at sea these days.

Signaling is a really intense study. It goes by each railroad as they have their own ideas and so varies from area to area and road to road.

I do not speak from experience on this as I have not gotten around to that on the LM&E. But I agree with what has been said that on model RRs, unless it is an extrememley large one, it is something like selective compression. There is really a small amount of it which will go a long way. Be very selective in your choice and consider the overall effect and what will look the best and that will do.

This is the opinion of an Ol’ Phart and not liking unessissary work and expense.

Best Wishes to you Ol’ Salt.

Johnboy out…

7

LIONS LOVE SIGNALS, and him having 14 miles of track has need of many block signals, especially since blocks on subway systems are measured in feet instead of miles.

OK you wanted interlocking signals. The easiest way to do this is to just use them as indicators for the position of your switches. If you have a complex interlocking plant, the signals would typically be at the enterence to the plant and NOT for each switch, although you could put a dwarf at each turnout just to incicate to you what is happening.

Here are instructions from the LION:…

Typicaly in a plant like this the down position of the levers is the NORMAL position for that device (turnout or signal). Normal positon for signals is RED.

Not show nere are the signals for the departing tracks from this station. The departures from those tracks would be controlled by lever 14 with a reepeat signal controlled by turnouts 6, 8, 9 and 10.

On the row of levers, the signals are painted red, turnouts black.

For a train arriving from the left ALL of the signals are on the left of the row of levers. For a train arriving from the right, the signal levers would be on the right end of the row.

A train moving from right to left on this diagram would need levers 1 and 3 reversed to display green lights.

A train entering from the left and terminating on track 4 would need levers 9, 6 and 5 reversed before levar 1 could be moved to clear the signal. This might display an amber signal on mast 1 since it is clear and diverting, but that is not shown here for simplicity.

On interlocking plants there are mechinical (now electrical) devices that force the correct sequence of lever movements before a signal can be cleared.

In my second example, signals 15 and 16 would be locked against movements into the station unt

8

The series started in January, with a multi-page installment every month (ten so far, obviously) with more to come. It explains the various prototypes and how to model them, too. If you’re interested in signalling, well worth a subscription and/or ordering back issues.

Wayne

9

For the basic, default modern prototype practice, John Armstrong’s “The Railroad: What It Is, What It Does,” is essential. To put it at its simplest, signals come in two types: those that are set by an operator (usually, but NOT entirely, interlocking signals), and those that are operated automatically (intermediate signals, also known as ABS, and also things like grade crossing flashers). Just to confuse things further, there are even semi-automatic interlockings.

An interlocking plant is a controlled complex that includes, at a minimum, a set of signals governing entry into interlocking limits; it may also include switches, crossovers, derails, etc. The key distinguishing features are 1) an operator or dispatcher physically controls the setting of switches and signals, 2) which are interlocked so that a conflicting (i.e., unsafe) route cannot be lined through the interlocking. If you see a signal out on the railroad without a number plate, it is usually an interlocking signal. For more info on interlockings, you should check out “A Model Railroader’s Guide to Junctions,” by Kalmbach.

Automatic/intermediate signals are those that simply detect the presence of a train in a given block, and display a signal to protect it (they will also trip for open switches, which can be importan). Usually this is done through an electric track circuit; the presence of a train shorts the circuit and causes the signal to drop automatically to stop. When the train leaves the block, the current returns. Modern signals are “approach circuited,” which means that the presence of a train in the adjacent block causes them to display a yellow “approach” signal. When the train leaves that block, the signal drops automatically to “clear.” ABS (automatic block signals) are usually distinguishable by a plate on the mast. In double track territory, each line may be signaled for movement in one direction (in

10

If you have an approach (prepared to stop at next signal) in 562 territory, and there is no fixed signal, how do you know where to stop?

11

Full working interlocking plant signals are easily done with a simple $3 relay for each turnout or crossover and basic detectors - way less expensive than any of the solid state/computer/plug and play options…gee, the prototype used relays for 100 years…still using them in many places…

Sheldon

12

I don’t know for sure, but I suspect you’d get a series of CSS drops, first to approach, then to restricting, and then to stop - the latter coming in advance of the actual end of the block through the use of code change points.

13

Even though there may not be wayside signals, there still are signal circuit blocks. If nothing else, there probably will be a relay cabinet or house at the boundry. After working a territory for a while, day in and day out, you begin to know where they are. When you enter a new block and the cab signal goes from Clear to Advance Approach (or the equivalent depending on rules in use), you have an idea where the train ahead (or whatever is causing the detected occupancy) is at.

Cab signals don’t have an aspect for stop. The most restrictive indication is Restricting. When operating on a Restricting cab signal you operate under the provisions of Restricted Speed. That is, in it’s simplest form, to stop short of anything that

14

That makes perfect sense- the most restrictive indication ABS can display is a stop and proceed, and rule 562 would only apply between the interlockings (which would retain home signals).

15

[quote user=“jeffhergert”]

MidlandPacific

steemtrayn

MidlandPacific

… and have “562 territory” (no fixed lineside signals, all movement is governed by “cab signal” systems in the locomotives).

If you have an approach (prepared to stop at next signal) in 562 territory, and there is no fixed signal, how do you know where to stop?

I don’t know for sure, but I suspect you’d get a series of CSS drops, first to approach, then to restricting, and then to stop - the latter coming in advance of the actual end of the block through the use of code change points.

Even though there may not be wayside signals, there still are signal circuit blocks. If nothing else, there probably will be a relay cabinet or house at the boundry. After working a territory for a while, day in and day out, you begin to know where they are. When you enter a new block and the cab signal goes from Clear to Advance Approach (or the equivalent depending on rules in use), you have an idea where the train ahead (or whatever is causing the detected occupancy) is at.

Cab signals don’t have an aspect for stop. Th

16

Seems that PRR and Union Switch and Signal started trying out cab signaling prior to 1930:

https://en.wikipedia.org/wiki/Pulse_code_cab_signaling

17

True enough, but mile for mile of trackage, very limited use until modern times.

And, OK, I should have said before such technology was common place or wide spread.

Sheldon

18

Some railroads no longer have stop and proceed signals. A signal displaying red with a number plate is now a Restricted Proceed on some railroads.

I work with two types of cab signals, the UP Coded Cab Signal with 4 aspects: Clear, Advance Approach, Approach and Restricting. I only run about 30 miles of that.

The other is the exCNW’s Automatic Train Control with a two aspect cab signal: Clear and Restricting. Until UP put in CTC and wayside signals, we only had waysides at control points and the advance signals to them. You would be going along at track speed, cross into the next signal circuit block and the cab signal would go to restricting. Meaning, depending on speed you either had 70 seconds to get below 22mph or 6 seconds to make a brake application. Otherwise you receive a penalty brake application that will require you to stop. The ATC dates from the 1920s.

Jeff

19

And what you describe on the UP makes a very effective signal system on a model railroad. Signals only at control points with the approach or advance signals.

Sheldon

20

Both LIRR and MNCR were members of the committee to establish NORAC, but both of them dropped out of the protocol. Each has their own rulebooks.

Thus LIRR operates with its own rule book east of Harold Tower, and NORAC west of the tower (On AMTK teritory)

Likewise AMTK uses NORAC but on the tracks of Metro North, they must follow MNRC rulebooks.

MNCR (Metro North Commuter Railroad) Uses its own rules, and does not operate off of its own rails, except for West of Hudson Services, but that is operated for them by NJT.

AFAIK, NJT uses NORAC on AMTK property, and probably also uses it on their own routes.

ROAR