Howdy-
What is “Interlocking” and what does it mean to me (my layout) ? I have been researching (primarily the PRR) and keep running into this term. My guess, from context, is that this is the area of a railroad controlled by one centralized switching/dispatching office? Is this correct? Is there something more?
Is there “interlocking” between railroads? (ie. an interchange?)
Thanks
An interlocking is basically where the turnouts and signals are interlocked so that throwing a turnout and lining a signal won’t cause a collision between trains. It can be the end of a siding, a set of crossovers, or a junction between two or more crossing lines.
An ‘Interlocking’ is a control point(usually a junction or crossing) that is controlled by an ‘interlocked’ signal system. These systems prevent conflicting movements of trains. An example would be a junction where a branch splits off of the mainline and the switch/signals are controlled by a tower operator(under control of a dispatcher). Complex interlocking examples may include the throat to a large passenger terminal, or be as simple as the junction or an ‘on grade’ railroad crossing. Sometimes the leads to interchange tracks may be part of an interlocking.
Current language is ‘control points’ in modern railroading. The ‘Interlocking’ was the old locking bar frame that was in the bottom of a tower and did the logic work to prevent the tower operator from setting up conflicting moves of the switches/signals.
Jim
See
http://en.wikipedia.org/wiki/Interlocking
http://en.wikipedia.org/wiki/Interlocking_tower
http://mysite.du.edu/~etuttle/rail/lock.htm
http://www.nymr.demon.co.uk/signals/signalling_1.htm
http://mysite.du.edu/~jcalvert/railway/railhom.htm
http://www.railroadsignals.us/
For a good book on the subject,see
http://books.google.com/books?id=BB7yLEFxpM0C&dq=mechanical+railway+signalling
Have fun
http://en.wikipedia.org/wiki/Interlocking
What does interlocking mean on a model railroad ? Normally not much.
If you want to simulate the appearance of an interlocking you put a tower building next to a crossing where one line crosses another. The tower would contain the interlocking mechanism which prevented the tower operator from setting up crossing/conflicting paths through the crossing at the same time.
If you want to simulate the function of an interlocking plant, you are in for an potensially expensive foray into the world of electronics and possibly computer controlled layouts. It is probably far easier and far less expensive to just manually stop one train when it is in danger of hitting another train at a crossing [:D]
Smile,
Stein
You need not only the tower, you need signals with different aspects.
Wolfgang
My end-of-the-railroad module is functionally interlocked:
The distant (approach) signal can’t be cleared unless a home signal is clear. If the distant is NOT clear, trains stop automatically before reaching the home signals.
Only one home signal can be cleared at any given time (there are two.)
No home signal can be cleared if a start signal has been cleared, and vice-versa.
Switch points cannot be moved if a signal has been cleared allowing a train movement over them.
No signal can be cleared unless the switch points along the cleared route are properly aligned.
If all signals are set to restrictive (horizontal semaphore blades) all switch points may be moved without interference.
The circuitry is a bit complex, but hardly arcane. It depends on the switch machine and semaphore actuator contacts to allow circuits to be completed or kept open. Using analog DC and the MZL system, the auto train stop circuit requires the only &#
No. You may want the extra realism of having signals that show appropriate aspects in the different directions. But you do not need em. No more than you need the tower itself.
This is modelling. You decide for yourself how complex you want to make your model, and what aspect or aspects of reality you want to model.
You can model interlocking at many levels - from simply watching out and manually stopping one train to wait for the other at a crossing, to adding working lights or semaphores, to going fully automated with electronic circuits, possibly combined with a computer program (in the case of DCC) to make the right train stop safely at the right place without human intervention, or even using a computer to create an interlocking plant where you will be prevented from throwing a turnout if that would set up two conflicting train paths through the area.
This is blindingly obvious both for you and me, of course, Wolfgang - but perhaps not quite so obvious for someone who is new to this hobby, as the original poster seemed to be.
Grin,
Stein
I had a friend who took college psychology, and while I normally try to shun people with just enough information to be dangerous, he said that men are basically divided into two camps: toy oriented and games oriented. While I’m basically toy oriented, liking model trains, building and operating them in a realistic environment, I guess my friend was wrong, because I, like a lot of model railroaders, have a little game orientation! I like the idea of operating a model railroad like the real thing, and if I were ever to build my Dream Railroad, I’d want to use the popular card order car dispatching.
I also find interlocking fascinating and when Paul Larson and Gordon Odegard did a series on designing and building an old-fashioned interlocking plant for Larson’s Mineral Point & Northern in the 1961 Model Railroader, I studied the workings avidly. The interlocking plant guarded a junction (originally called Gratiot–pronounced “Gra-SHET,” and when people couldn’t pronounce it properly, changed to Shu
Hi jwhitten
Interlocking is the mechanical or electrical control of points and signals in such a way as to prevent opposing moves or other dangerous situations.
In model form it all depends on how complicated the layout is as to if it is needed or wanted.
It would be sensible to tie signals and points together so that the signal indications can only match the way the points are set and that any opposing signals cannot be cleared.
But that is only if thats what you want to do.
Just by having a signal box and a couple of signals it is represented but it does make sense to interlock some things together as you see fit.
regards John Busby
See this article
http://modratec.com/download/pdf/lock01.pdf
From this site
To repeat a book link listed above
For a good book on the subject,see
http://books.google.com/books?id=BB7yLEFxpM0C&dq=mechanical+railway+signalling
See also
http://books.google.com/books?id=LYQ5AAAAMAAJ&pg=PA4&dq=railroa
An example of a fairly simple interlocking situation was one that I’m looking at trying to model, it was called “State Line Tower” and was located where the Northern Pacific’s single track ore line crossed the Great Northern’s double track ore mainline, near the border of Minnesota and Wisconsin. The interlocking tower was run by GN and normally the signals were set to allow GN trains to go across the diamonds without stopping. If an NP train needed to cross, the control levers were set up so that the tower operator couldn’t throw the lever to give the NP train a go-ahead signal until he had set the GN tracks to “stop” in both directions.
BTW interlocking signals (especially in the steam era) were different than block signals in that they normally had two heads. This is because with a normal single head block signal, red often doesn’t mean “stop” as it does with say a red light at an automobile stop-and-go light, but is what’s called “permissive” meaning you can slow way down and proceed into the next block, prepared to stop if something is seen ahead of you. Obviously this woudn’t work at a crossing of two railroads, so an interlocking signal would often show red-over-red (two heads, both showing red) to indicate this was an interlocking and so was an “absolute” stop. Often in a simple crossing, one head would be a ‘dummy’ that would only show red…so you might have a lower signal that would always be red, so you could show red-over-red for stop and green-over-red for proceed.
An interlocking could also be a place where a rail line split, like say a branch line leaving the mainline. In that case, as you approached the split, your signal could show green-over-red (proceed on mainline), red-over-green (proceed on branchline) or red-over-red indicating a stop. Think of it like driving your car and you come to a place with regular stop-and-go lights for two roads that cross each other, but also a left-turn la
An interlocking signal for a crossing at grade of two single track railroads would have eight SINGLE head signals, a home and distant signal for each direction. The distant signal could indicate either clear (green) or caution (yellow)(if the home signal was red). The home signal could indicate stop (red) or preceed (green). Since there was only one route over the crossing only one head was needed, the speed and route were always the same for a given diretcion. That the home signal was an absolute signal would be indicated by the LACK of a number board below the signal head.
Have fun
So then a model railroad example of an interlocking would be a double crossover between two parallel tracks in which all four turnouts are activated by a single switch with the switch motors set up to run all trains either straight past or through the crossover?
Some fine day this will be an interlocking:
Or a video from the opposite direction: http://www.youtube.com/watch?v=EXx3c5OOl0s
I wait for the signals at the other side. And then comes wiring.
Wolfgang
Thanks everybody who replied-- I have been re-reading these posts as I’ve been working out my track plan and am just astonished at the wealth of information and detail folks here have. Boy I have a lot of catching up to do!