it's clear to me that signals can be interpreted in different ways depending on era, RR and situation.
my questions was what makes sense for model RRs who aren't trained to interpret the wide variety of possible signals or who may be unfamiliar with the unique situations on a particular layout.
here in Cumberland, CSX has 3 headed south facing (compass) signals at the fairgrounds. the bottom signal indicates that the northbound train should stop before the access road to the fairgrounds. the top signal indicates that it is clear thru Viaduct Junction. but the middle signal indicates to stop at the bridge to avoid blocking city streets or for a possible crew change (note the woodend staircase between the track and road)
i'm told there is a similar situation on the tracks from Pittsburgh leading into Cumberland. there's a crew change point at a billboard in the narrows.
2497
greg - Philadelphia & Reading / Reading
In "How to Operate Your Model Railroad" author Bruce Chubb had a good section on signalling. He said that for most model railroads, very simple signals (one head with two lights, two heads each with two lights, and one head/two light dwarfs) would really be all you need. He pointed out that making a rule that a single red light always means 'stop' (unlike the prototype where it can have different meanings) helped a lot to make things simpler.
I'd say too that to keep it simple, you would want to keep it consistent. Having say green means you're clear to proceed, red means stop, and yellow means you're turning off onto a side track or branchline or whatever, isn't perfectly prototypical, but could be a simple, easy way for people to understand what's going on.
gregc it's clear to me that signals can be interpreted in different ways depending on era, RR and situation. my questions was what makes sense for model RRs who aren't trained to interpret the wide variety of possible signals or who may be unfamiliar with the unique situations on a particular layout. here in Cumberland, CSX has 3 headed south facing (compass) signals at the fairgrounds. the bottom signal indicates that the northbound train should stop before the access road to the fairgrounds. the top signal indicates that it is clear thru Viaduct Junction. but the middle signal indicates to stop at the bridge to avoid blocking city streets or for a possible crew change (note the woodend staircase between the track and road) i'm told there is a similar situation on the tracks from Pittsburgh leading into Cumberland. there's a crew change point at a billboard in the narrows. 2497
I have no thoughts on the prototype situation you describe, it has no bearing on what is practical for our model layouts.
On our model layouts we can simply make do with a limited number of aspects and only use interlocking or absolute signals in all cases.
So, signals with one head, red = stop, yellow = approach prepare to stop at next signal, green = clear.
Two heads assumes an interlocking, G/R = main route clear, Y/R = main route approach, R/G = diverging route clear at specified speed, R/Y = diverging route approach prepare to stop at next signal. R/R = stop.
Three heads assume a more complex interlocking. Aspects for top two heads apply, third head indicates more restrictive diverging route, R/R/Y = restricted speed route clear, R/R/R = stop. Third head will be red when either upper head shows other than red.
That is simple and all most layouts need.
Easy to learn, ALL RED = Stop, Green on top means clear for the main, everything else means slow down.
Forget the rest of the prototype aspects and rule books.
Sheldon
One other note, my simplified signals use even less aspects than I listed above.
Two and three head interlocking signals never show Yellow "approach" on the two upper heads. My blocks are long and with DC control the status of the block past the one you are entering is not important.
Secondly, in place of those "approach" aspects, there is a single head signal half way thru the block, it is an approach signal for the next interlocking and never shows "stop", it shows green when the next signal is green, and yellow when the next signal is red.
This provides more information while using fewer aspects for the operators to learn.
ATLANTIC CENTRAL On our model layouts we can simply make do with a limited number of aspects and only use interlocking or absolute signals in all cases. So, signals with one head, red = stop, yellow = approach prepare to stop at next signal, green = clear.
In or about 1977, the entire Star Wars genre began with a simple declarative statement of fact: . . . a long time ago in a galaxy far, far away . . .
Who doesn't love a place where the rules are clear cut and concise?
Robert
LINK to SNSR Blog
ROBERT PETRICK ATLANTIC CENTRAL On our model layouts we can simply make do with a limited number of aspects and only use interlocking or absolute signals in all cases. So, signals with one head, red = stop, yellow = approach prepare to stop at next signal, green = clear. In or about 1977, the entire Star Wars genre began with a simple declarative statement of fact: . . . a long time ago in a galaxy far, far away . . . Who doesn't love a place where the rules are clear cut and concise? Robert
Agreed, and the interesting thing is that the aspects I do use are pretty much correct for the situations and the era I model.
wjstix refered to Bruce Chubb and his early work on signals and operation, much of what I do is based on his work, as well as Paul Mallery and Ed Ravenscroft.
Too many people in this hobby today have failed to understand the idea of "selective compression", not just in physical size, but in complexity.