«Compiled by: Dick Bronson RR-CirKits, Inc. Installing a signaling system on your layout. Types of ...»
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 ??) Search light Standard in the US&S, GRS Sunrise Enterprises ??, BLMA, ISS, West Tomar, Oregon Rail Supply Color light Stacked, V (Cat Standard for US&S, GRS, BLMA, ISS, Tomar, Oregon Rail face) modern signals Safetran Supply Position Light Route and Speed Pennsy, N&W US&S, GRS, Tomar, ISS, NJI, Oregon Rail Supply Safetran Color Position B&O Speed B&O, N&W US&S, GRS Tomar, ISS, NJ International, Oregon Light only with 6 post 1959 with Rail Supply optional marker Route 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.
Semaphore Signals Upper Quadrant Lower Quadrant SP Extra 6516 West splits the semaphore signals at Winchester, TX Searchlight Signals Prototype Model Color Light Signals Position Light Signal Mapleton, PA is the next set of signals west of Mt Union, about two miles away.
Position light signals were used by the Pennsylvania RR as
Block is the section of track being protected by a signal. It does 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.
Aspect The speed or route indication given by one or more signal heads or arms.
Indication is what the aspect means. 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 called 'vital logic'. The vital logic resides track side and responds immediately to local conditions.
The CTC system overlays the vital logic with information from the dispatchers machine. This information was in the form of command codes and indication codes. The dispatcher could only command a direction of traffic and turnout positions. The local control point (vital logic) was in charge of actually changing the signals and reported back to the CTC operator when it had done so.
CTC machine Active Union Switch and Signal CTC machine at Amtrak's THORN Tower.
Interlocking Plants 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. Color coded levers indicated, signals (Red), spare (White), locks (Blue), and points (black). There are two positions, Normal (back), and Reverse (pulled forward), with latches at both ends. Thus ”Signals Normal” means ”Stop”. The horizontal bars behind the levers slide back and forth to block all 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 200911 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 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 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!
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 the 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, 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 positions of turnouts so that operators don’t run them. These can easily be wired to act as simple indicators 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 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 as DC block boundaries, for example) Semi-functional are lighted (or movable in the case of Semaphores), but may not be 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
stuff under the hood to make them work. There are several approaches to this ranging from, standardized logic modules, to dedicated controllers, to software systems hosted on a 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. Hardwiring 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!
Other Considerations Signals should be aimed so the operators can see them (may not be at the train) OR have repeaters (which may also help the color-weak operators). While cosmetic signals need only match the photo of the location you are modeling, operational signals must be able to tell your operators what to do, so they have to be able see the aspects displayed! In many cases the prototypical orientation of signals will not permit viewing by the operator at a convenient point. Check each signal location and ensure that the signal will be visible. If it won’t be, you can either modify the orientation so it is aimed at the operator (rather than at the 1/87th engineer) or provide repeaters on the fascia or valence. While repeating, if you are using search light signals on the layout, consider using color-lights on the repeaters as about 15% of males are color blind to some degree.
Electrical infrastructure – Signaling systems depend on knowing where the trains are. Generally this done with block occupancy detection using current detection – somewhat like prototype track circuits – but optical detectors are sometimes used, especially for point solutions like grade crossing signals. You should map out where your signals are going to be located and what the detected blocks should be before you start power wiring. Track will need to be gapped accordingly.
Be sure to check out our website at http://www.rr-cirkits.com for detection hardware and signal drivers.
Check clearances (your widest locomotive and longest rolling stock may overhang more than the NMRA standards gauge which represents Plate C; your modern equipment may be plate F!). Make sure your dwarves, pot signals and signal bases will clear. Western modelers: borrow an SP GS4 and be sure that huge pilot will clear!
If you have equipment that exceeds the NMRA clearance gauge, check with that: a long wheelbase steam engine and full length passenger cars are a good torture test! Note the inside clearances on long cars with overhang, too. You may need to adjust your track to track spacing by an additional 0.5 inches or more. Signals are often located on curves which may exacerbate the overhang.
Relay sheds, boxes – the signal is just a series of lights with some kind of support. The track side “vital logic” had to be housed in some kind of enclosure: either the base under the signal or a shanty nearby. These take up space on your right of way and need to clear your equipment. Be sure to include these little details along your right of way. They are an integral part of the signaling scene, and can make or break the impression of realism that we are trying to create. Even those folks that know nothing about signaling systems still have a sense of what looks right or wrong about a scene.
Pole Lines – The signals need power and in the case of CTC, control.
This was typically provided by the pole line which often carried telegraph or telephone as well. If you choose to model the pole line, it must go along the right of way and out of the way of your trains. Poles lines typically had at least one cross arm and often many more. Check prototype photos! Interestingly CTC systems did not necessarily have more cross arms as a single pair of “code wires” could control up to 80 miles of railroad. In more modern times, the pole lines have been superseded by radio or fiber and the pole lines are abandoned – a seldom modeled feature.
Dispatcher and Operator positions
routes or eliminating some of the tricky cases.
What % of the total cost of your Railroad are you willing to devote to signaling? Our (LDSIG) large system example is about 10% of the cost of plastic motive power and rolling stock Since more than half of the cost of your signal system is in the signals, it doesn’t make much sense to skimp on the control logic.