«Compiled by: Dick Bronson RR-CirKits, Inc. Installing a signaling system on your layout. Types of ...»
Portland Daylight 2015
Signaling Your Layout
Compiled by: Dick Bronson
Installing a signaling system on your layout.
Types of Prototype Systems
Train order signals
ABS (Automatic Block System)
APB (Absolute Permissive Block)
CTC – TCS (Centralized Traffic Control – Traffic Control System)
Signal Types Type Variations Unique Roads Prototype Mfgs HO Model Manufacturers Ball Signals Semaphore Upper, lower US&S, GRS Tomar, N J International, (Oregon Rail Quadrant Supply #152 #155 ??) Marklin Search light Smaller than normal Used in many US&S, GRS BLMA, ISS, Tomar, Oregon Rail background used by regions until Supply NYC modern times BLMA, ISS, Oregon Rail Supply, Tomar, Color light Stacked, V (Cat Standard for US&S, GRS, T.R. Castings, Details West, Atlas, Busch, face) modern signals Safetran Marklin, Model Power, Viessmann, Bachmann Position Light Route and Speed Pennsy, N&W US&S, GRS, Tomar, ISS, NJI, Oregon Rail Supply Safetran B&O Speed only B&O, N&W post Color Position US&S, GRS Tomar, ISS, NJ International, Oregon with 6 optional 1959 with Route Light Rail Supply marker lights Dwarf N&W unique US&S, GRS Tomar, Oregon Rail Supply fan shaped CPL Signal Bridges Overland, BLMA, Oregon Rail Supply and Cantilevers Train Order US&S, GRS Tomar Boards Ball Signals Whitefield Junction marks the crossing of the Maine Central Railroad and the Boston and Maine Railroad in Whitefield, NH. According to a plaque that stands near by this is/was the last remaining ball signal still in use in the United States.
not necessarily correspond to the electrical blocks used for power distribution, but it is helpful if it does.
Home Signal indicates the state of the block immediately ahead of the signal Distant Signal is a second signal (lower on the mast) showing the aspect of the next signal ahead. This should not be confused with the dual heads of a CTC system where the second head is used to indicate other conditions such as take the siding or a reduced speed. As signals became more complex a third 'approach' aspect was added to give this same information.
Appearance is what the signal looks like. e.g. Red over Yellow.
Aspect The name of the speed or route indication given by one or more signal heads or arms.
Indication is what the aspect means. (what you need to do) These differ by railroad and era (hence are very useful for setting your railroad in a time and place). They can convey either route (common in the West) or speed (common in the East) information. Signaled railroads provide an aspect chart in their ETT or rulebook.
Signal Arm or Signal Head indicates each individual signal unit.
Light The individual lamp in a signal. A light may indicate multiple aspects if it changes color like in a searchlight signal, or it may take multiple lights to indicate a single aspect, for example in position light signals.
Marker is a signal head or arm that does not change color or position.
Mast is the assembly that carries one or more signal heads. The engineer needs to consider that all signal heads on a single mast give a single indication or aspect. E.g. If its not all red, then its not red at all.
Rule refers to the numbered entry in the prototype's publication governing the operating department. For example: from the 1937 NYCS rule book.
Rule 281: Clear Indication: Proceed
basic ABS or APB signal system which is called the 'vital logic'. The vital logic resides track side and responds immediately to local conditions.
The dispatcher can only command (allow) a direction of traffic and turnout position. The local control point (the vital logic) is in charge of actually changing the signals and reporting back to the CTC operator if and when it has done so.
The CTC system overlays the vital logic with information from the dispatchers machine. This information is in the form of command codes and indication codes. Because of the human element, CTC does give operating authority to trains.
Control Codes To transmit a control code, the dispatcher positions the necessary levers on his CTC machine. Next, he pushes the appropriate code start button that causes the code to be transmitted. All field locations connected to the code line see the control codes, but only one station is selected. At the selected location, the control portion of the code is delivered to and stored in the field relays to cause the function relays to operate the switches, signals, etc.
THE ENGINEER Sept. 17, 1943 Control Codes Each control code takes about 3 ¾ seconds to send. Each code consistes of sixteen periods when the current is first 'on' then 'off'. Each of the periods may be long or short to indicate if its data is true or false. The first portion of the code selects the station and the remainder select the operations to be performed.
The original system had a maximum capacity of 35 stations per line pair. Of course if the CTC machine was centrally located, then 70 stations could be controlled. Each passing track consists of two stations.
The classic CTC machine had 15 sections per panel. A large CTC machine would have 4 panels for a total of 60 stations using two code lines.
The range of a code line was about 80 miles.
Indication Codes When a field change occurs in the position of a switch, the aspect of a signal, or the condition of a track circuit, an indication code is set up at the field location, which in turn automatically transmits the indication back to the CTC machine. When the indication code is received at the CTC, it is stored in relays, and the appropriate indications light up on the dispatcher's panel to show the conditions existing at the field locations.
A similar method to that of the control codes is used by the field equipment to send the station indications back to the dispatcher.
Only one code may be sent at one time to or from any station. If several stations need to send information, each is queued in station priority until higher priority stations have completed sending.
CTC machine Active Union Switch and Signal CTC machine at Amtrak's THORN Tower. This machine is direct acting, so it doesn't use conventional code lines for communication. It includes additional controls for catenary power and heaters, plus dragging equipment indicators.
NMRA LCC (Layout Command and Control) What has been will be again, what has been done will be
US&S code line on Steroids.
All the data travels on one circuit.
Only one code may be sent at a time.
Messages are prioritized and queued if the line is busy.
Codes are only sent when something changes in the system.
Local equipment remembers these changes in order to display them.
NMRA LCC (Layout Command and Control)
Interlocking Plants are used to protect crossings or junctions. Prior to the introduction of Centralized Traffic Control (CTC) in the 1920s, interlockings almost always had a manned tower with a towerman who controlled the switches and the signals protecting them with a system of levers and rods. These signals granted authority to enter the interlocking plant and were arranged so they could not display favorable aspects unless all switches were thrown properly, and any routes not selected were blocked. These were called Armstrong systems for a reason. The color coded levers indicate, signals (Red), spare (White), locks (Blue), and points (black). There are two positions, Normal (back), and Reverse (pulled forward), with latches at both positions. Thus ”Signals Normal” means ”Stop”. The horizontal bars behind the levers slide back and forth to block all possible movement to any disallowed combinations of positions.
Typical CTC siding West Main OS Section Main OS Section East Main
Note the different gaps and detection sections required for these two signal options. Many mainline CTC sidings are also occupancy detected.
Model Signals Much of the following information was taken from the ”Planning for Signals” discussion held by the LDSIG at the 2009-11 NMRA national conventions. I had the priviledge of sitting on these panels.
Signals can be an exciting addition to a model railroad, adding color, realism, operating interest and functionality to your modeled scenes.
Early on in your consideration of adding signaling to your plan or existing layout, you'll need to choose, as you did in planning your layout, whether to model a prototypical scheme, a freelanced but prototype-based scheme, or freelanced signal elements that add some visual and operating interest but don't follow any typical prototype engineering.
Real-life railroad signaling is highly road, subdivision, and era specific. For maximum realism, you should obtain a copy of the rule book and special instructions and track charts, if available, for your division in the era you plan to model, or if freelancing based on a prototype, use the documents for one of the prototype roads you had in mind when you imagineered your railroad.
If you think of planning a layout as telling a story, hardly anything you can do on your railroad will set it in a particular location and era like the correct signals, so spend some extra time finding photos and understanding the signaling system.
It's certainly possible to include some more generic elements in a freelanced scheme, but be warned that you may not find these as rewarding as a more realistic prototype-based system. Read on for more information to help you decide!
Federal regulations and mergers are wiping out many of the former distinctions between signal systems. This means that modern era layouts may lose many of the distinctions seen in older eras.
Signals also help with operations: they convey authority to occupy track in interlocking plants, inform crews of train orders and may provide authority to occupy the main. If you are planning an operating layout you should consider how signals will help you with these requirements.
Railroads use signals for four general purposes, although more than one may be used in any area (interlockings, train order signals, safety overlay (ABS/APB), and traffic control (CTC/TCS). As modelers following a real or imagined prototype, we can use signals for these same purposes.
Functional signals perform more or less as the prototype signals do, subject to selective compression, whereas cosmetic signals are just there to set the scene and perhaps do some very limited function such as turnout position indication.
In the cosmetic case you might use operating or dummy signals and light them permanently or under control of a timer or slide switch, but be sure to put them in right places. While these signals won’t be used operationally, they will make your photo contest entries look great!
Model Interlocking Plants often indicate the positions of turnouts so that operators don’t run them. These can easily be wired to act as simple indicators, even if you don’t want to provide all of the prototype functions Train Order Signals – The earliest TO signals were ball signals but typically they were semaphores until well into the early 20th century. Some search lights and other indicators were used later. These signals were always located at a train order office where an operator could transcribe orders from the Dispatcher and physically hand, or hoop them up, to train crews. Check prototype photos as train order signals were iconic and defined the look and era of a station.
Some layouts only use signals cosmetically because the prototype had them. In this case you just need non functioning models put in the right places Cosmetic Signals can be further divided into nonfunctional and semi-functional approaches.
Non-functional are dummy signals properly located at sidings, etc. (not used to indicate DC block boundaries, for example) Semi-functional are lighted (or movable in the case of Semaphores), but are not tied to detailed signaling logic.
They may indicate turnout positions, whether adjacent DC blocks are assigned to the same or different cabs, reverse loop polarity, etc.
Semi-functional signals may also provide a basic ABS like function without fully implementing prototype rules.
Functional Signals Layouts with functional signals need all the stuff under the hood to make them work. There are several approaches to this ranging from, standardized logic modules, dedicated controllers, to software systems hosted on a personal computer. (E.g. JMRI, RR&Co.) In most cases the most difficult part is deciding what you want the signals to do. The difficulty of implementation depends on how closely you want to replicate the prototypical signal indications. Hard wiring of signal logic increases the difficulty of implementation versus a software based system which can be edited or edited and compiled into a module. Many straightforward tools exist to help you implement the signal logic once you have determined what it should be. This is why we stress study of the prototype; your prototype will tell you what to do!
Like the prototype, model signals may be controlled by
individual wires....… or over a code line.
Note the no longer used cross arms that may have carried communications circuits or signal circuits in the past.
Only two of the lower lines are used for the signals.
Others provide power to the line side equipment.