Protecting a diamond with signals?

[Dave-the-Train]

I have some progress!

Trackplan has solidified (or coagulated ).

I have a single line (A) crossed by another single line (B) at grade.  Second line divides straight after the diamond to become 1st and 2nd Main (B1 and B2).  All roads are bi directional,  There is a running connection between A and B2.  B1 is between A and B2. A and B1 (maybe B2) carry some passenger traffic.

I'm looking at Oregon Rail Supply's 401 single searchlight and 402 double searchlight signals - which are the ready built versions of these two...

http://www.walthers.com/exec/productinfo/538-125 & http://www.walthers.com/exec/productinfo/538-127

First question is whether these would be suitable for an interlocking or CTC controlling a diamond like this in the 80s?

2nd ... I am assuming that I use one head where the route ahead doesn't divide and a double head where it does.  Is this correct?  ... or at least; one way of doing it? 

Thanks

[cv_acr]

Dave-the-Train

I'm looking at Oregon Rail Supply's 401 single searchlight and 402 double searchlight signals - which are the ready built versions of these two...

http://www.walthers.com/exec/productinfo/538-125 & http://www.walthers.com/exec/productinfo/538-127

First question is whether these would be suitable for an interlocking or CTC controlling a diamond like this in the 80s?

Yes. Note that the picture of the 2-target signal shows the kit assembled with the heads staggered on opposite sides of the post, making that a block signal. A CTC control signal would have both heads vertical on the same side of the post. (The ORS signal is a kit, so will be able to be assembled in either configuration.)

2nd ... I am assuming that I use one head where the route ahead doesn't divide and a double head where it does.  Is this correct?  ... or at least; one way of doing it? 

That may depend on the signal rules of the road you're modelling. On many roads an absolute stop is Red over Red, so even on a route that doesn't divide or merge through the curved leg of the switch you'd have a 2-target signal, but the bottom light would never be anything but red. You see the same thing at the end of a controlled siding at the trailing end of the switch on the main track. The only possible route is straight through, but the bottom red is required for the absolute stop indication.

A signal head signal is typically a simple block signal, but on some roads depending on the signal rules in effect, could be used as an absolute control signal (especially with APB signalling, but also for CTC control signals _depending on the signal rules in effect_.)

(Note that signal rules and indications do differ between railroads sometimes, but the above is common both on several US roads and pretty much every Canadian road that actually has any sort of signalling.)

[nbrodar]

 Dave kindly provided me with a drawing...so here it is for everyone...

Assuming CTC, the protection for the diamond would be incorporated with the protection for the A/B and B/B crossovers.

Single head signals could govern the diamond's North and East A approaches, most likely though, it would be a two headed signal with the bottom head permanently red.  West and South two heads.   East B could be a two or three head.

Nick

[Dave-the-Train]

  AARGH!    This always happens!

I really can't get my head round US practice.

Thanks for the replies.   They've completely thrown me. 

Area |(give or take 50 miles) is Chicago.  RR... not sure... something like BRC or EJ&E.  (Can't say I've actually noticed any signals on either but I'm freelancing a bit).  Time is 1980s.  Line A has far-end-of-the-route Metra 1 an hour shuttle.  Line B has one-a-day Amtrak.  (This is all as waffled about in my previous "Chicago 80s" thread).

I've recalled... APB = Absolute Permisive Block.    I think?    That's scarey weird stuff.   I'd rather go for absolute signals probably with a tower but CTC would be okay.

It sounds like I might need to wait and get kits to put the heads where they need to be???  One two or three heads?  Okay so an Absolute stop has two reds the lower one of which may be always red... can that one give a "proceed" of some kind if the route is set through the curve of a switch/ the lesser route?

Thanks for posting the scruffy sketch Nick   Your answer has completley lost me though.   Any chance you could sketch in the signals when you've got time?

Another thing that has come up is dwarf signals ...  I'm wondering if they would be combined to indicate routes set or instead of mast signals (maybe on the second main)?

Perhaps it will sort the location out a bit if I think in terms of one of the lines being a spun-off chunk of the bankrupt Rock Island?  Or will that just rreally mess things up?

Would a recent change in the configuration of the diamond area make a difference... for example, lets say that the straight connection Line A (east) to Line B2 (2nd Main) has just replaced having to switch back through the dead end spur at the east end... ?

One thing that I believe used to happen was that the most recent people to make or alter any grade crossing were the people that had to do the new signalliing, pay for it and provide the tower.  Could this give me a bit of a way out.

Oh yes, one thing is that I was thinking of combining the protection for the diamond with the crossovers.  We would do that with a whole load of signals if the layout was bunched up close enough (for old style) but until very modern stuff we would be more likely to lay the track out very differently.  We have massively different operating conditions... well we did have before everything was supposed to hurtle point-to-point without stopping to do anything...

Thanks again

[cv_acr]

Dave-the-Train

It sounds like I might need to wait and get kits to put the heads where they need to be???  One two or three heads?  Okay so an Absolute stop has two reds the lower one of which may be always red... can that one give a "proceed" of some kind if the route is set through the curve of a switch/ the lesser route?

For slow speed through the diverging route, the green (or yellow) would be on the lower signal head. So a signal approaching the facing end of a siding switch would have 2 heads (for a Slow speed switch) and the indications would be Red/Red for stop; Green/Red or Yellow/Red for straight through, and Red/Green or Red/Yellow going into the siding. (Simplest case.) Coming out of the siding, or merging onto the main track through the curved part of the switch, if you are using a full mast signal on that track (which you would if it's actually two main tracks going down to one) then the signal on that track would only ever have the green or yellow on the bottom (to display slow speed), and the _top_ light would be permanently red.

Thanks for posting the scruffy sketch Nick   Your answer has completley lost me though.   Any chance you could sketch in the signals when you've got time?

Another thing that has come up is dwarf signals ...  I'm wondering if they would be combined to indicate routes set or instead of mast signals (maybe on the second main)?

Dwarf signals can be used instead of mast signals, but they're used on secondary tracks, like a siding or other connection into signalled track. Dwarf signal indications are slower than the same combination of lights on a full mast (Green on a single-head dwarf is Slow-Clear, not Clear)

Perhaps it will sort the location out a bit if I think in terms of one of the lines being a spun-off chunk of the bankrupt Rock Island?  Or will that just rreally mess things up?

Not sure why that would make any difference.

Would a recent change in the configuration of the diamond area make a difference... for example, lets say that the straight connection Line A (east) to Line B2 (2nd Main) has just replaced having to switch back through the dead end spur at the east end... ?

One thing that I believe used to happen was that the most recent people to make or alter any grade crossing were the people that had to do the new signalliing, pay for it and provide the tower.  Could this give me a bit of a way out.

I'm not sure I follow. Any route through the interlocking has to be protected. I've actually heard of some cases where a route into an interlocking was removed, but they actually kept the signal in place to avoid the cost of rewiring the interlocking. If you actually alter the track arrangement or add something to it inside the interlocking protected by the signals, then you'd have to update the signals. The signals must take into account every possible route into or through the interlocking.

Oh yes, one thing is that I was thinking of combining the protection for the diamond with the crossovers.  We would do that with a whole load of signals if the layout was bunched up close enough (for old style)...

If it's close enough, the entire track arrangement can be combined into a single interlocking, which would use _less_ signals because you don't need any in the middle between the switch and diamond.

[cv_acr]

Note: With respect to 2-head vs. 3-head signals, it all has to do with speed.

The _top_ light on a signal indicates "full" (track) speed. Eg. Green/Red is "Clear" (no special restrictions)

An indication using the _bottom_ light indicates Slow speed. Eg. Red/Green or Red/Red/Green is "Slow to Clear" (slow speed through switches, then proceed at track speed.) (NB: under some rules a low yellow is actually "Restricting", and a low _flashing_ yellow is used for "Slow Approach" (aka. "Slow to Stop" under some rules))

An indication using the _middle_ light indicates Medium speed. Eg. Red/Green/Red is "Medium to Clear" (medium speed through switches, then proceeed at track speed).

Some variations also allow for "Limited Speed" (not full track speed, but faster than Medium) but those are more complicated combinations of lights on a 3-head signal.

 

Also, if you're taking approach signals to your interlocking into account, there are more possible indications on those approach signals as well, based on the speeds displayed at the next signal.

To wit, "Approach" (a.k.a. "Clear to Stop" under the current Cdn. rulebook) is your standard Yellow or Yellow/Red. (the next signal will be displaying Stop)

"Approach Medium" is Yellow/Green (the next signal will be displaying a Medium speed indication)

"Approach Slow" is Yellow/Yellow (the next signal will be displaying a Slow speed indication).

[Dave-the-Train]

Nooooooo!   Not approach signals Pleeeeease!    My head will explode!

  Seriously, thanks.

If I can work through the sketch... Left to right first (eastbound). 

RR A (top line) approaches the diamond and, once it has crossed RR B splits to add the Second Main.  Length constraints mean that this will be a short crossover with slow speed.  As I understand it so far a two head signal will show Green over Red for 1st Main and Red over Green for 2nd Main. - I'm wondering whether, if it's a very slow crossover, the signal will have three heads and give Red over Red over Green for 2nd main?  Would a 1980s alternative be two heads with Red over Yellow (no Green available)?

RR B (lower line) seems to need two heads.  This is the new connection and laid with longer switches so I'm figuring that both heads will show Red or Green as appropriate.  Green over Red for RR B's route and Red over Green for 2nd Main.

Going the other way...

RR B can only go to RR B so this seems to be Red/Green over Red only.

RR A 1st Main also only has one route so that seems to be Red/Green over Red Only

RR A 2nd Main gets complicated... It looks like The top head will always be Red.  I'm not sure which route will come next - to RR B through the faster switches or to RR A through the slow switch?  Then there's certainly the dead end spur and possibly a very slow connection to the switching loop...?

As I understand the answers so far the connections from the spur and switching loop coming out would be dwarf signals... might the spur be controlled by a derail with co-acting switch indicator?

The meandre of thought about the Rock Island was basically wondering whether a spun-off RR would keep RocK Island signals and rules to keep its life (relatively) simple...?

Thanks again

[dehusman]

Dave-the-Train

I have a single line (A) crossed by another single line (B) at grade.  Second line divides straight after the diamond to become 1st and 2nd Main (B1 and B2).  All roads are bi directional,  There is a running connection between A and B2.  B1 is between A and B2. A and B1 (maybe B2) carry some passenger traffic.

My question is what is the line that crosses line A?

Is it a main track?  Is it signaled?  Makes a big difference in what signals you display and whether you want more heads.

Are all the "lines" the same railroad or different railroads?

Dave-the-Train

First question is whether these would be suitable for an interlocking or CTC controlling a diamond like this in the 80s?

Yes.

Dave-the-Train

2nd ... I am assuming that I use one head where the route ahead doesn't divide and a double head where it does.  Is this correct?  ... or at least; one way of doing it? 

More or less yes, but the colors depend on the answers to the above questions.

[cv_acr]

Dave-the-Train

If I can work through the sketch... Left to right first (eastbound). 

RR A (top line) approaches the diamond and, once it has crossed RR B splits to add the Second Main.  Length constraints mean that this will be a short crossover with slow speed.  As I understand it so far a two head signal will show Green over Red for 1st Main and Red over Green for 2nd Main.

Yes. Clear for the straight route, Slow to Clear for the diverging route.

 - I'm wondering whether, if it's a very slow crossover, the signal will have three heads and give Red over Red over Green for 2nd main?  Would a 1980s alternative be two heads with Red over Yellow (no Green available)?

No. The only reason to have 3 heads is to be able to display the Medium speed indications (ie. Red over Green over Red)

RR B (lower line) seems to need two heads.  This is the new connection and laid with longer switches so I'm figuring that both heads will show Red or Green as appropriate.  Green over Red for RR B's route and Red over Green for 2nd Main.

Yes. Green over Red for the straight route, Red over Green (slow to Clear) for the connection to A)

Going the other way...

RR B can only go to RR B so this seems to be Red/Green over Red only.

Yes.

RR A 1st Main also only has one route so that seems to be Red/Green over Red Only

Yes, because it's a straight route.

RR A 2nd Main gets complicated... It looks like The top head will always be Red.  I'm not sure which route will come next - to RR B through the faster switches or to RR A through the slow switch?

Both routes are probably slow speed so the signal indication would be the same in either case. (ie. Red over Green) 

Then there's certainly the dead end spur and possibly a very slow connection to the switching loop...?

As I understand the answers so far the connections from the spur and switching loop coming out would be dwarf signals... might the spur be controlled by a derail with co-acting switch indicator?

I'm not quite sure from the description where these come in; if you posted a diagram my work computer is blocking the image. A short dead-end spur for an industry or just holding a few cars is probably even just an electrically-locked hand-operated switch. If it is powered it would have to have a dwarf signal which would just be a single light (Green on such a dwarf signal is "Slow to Clear") but that would be unlikely since a train can't actually enter the interlocking from there, only perform switching moves through the interlocking. (Of course, then you need to provide Restricting indications so that train can actually move through the interlocking when the next block is occupied to tie back onto their train. This complicates things and is only used at selected interlockings where this sort of Return-to-Train movement is likely to occur, and only on the tracks and directions that require it.)

[dehusman]

cv_acr

That may depend on the signal rules of the road you're modelling. On many roads an absolute stop is Red over Red, so even on a route that doesn't divide or merge through the curved leg of the switch you'd have a 2-target signal, but the bottom light would never be anything but red. You see the same thing at the end of a controlled siding at the trailing end of the switch on the main track. The only possible route is straight through, but the bottom red is required for the absolute stop indication.

It does depend on the rule book since in the rule books with which I am familiar with the number of heads doesn't have anything to do with whether or not its an absolute signal or not.

What makes it an absolute signal in most rule books is the abscence of a number plate or an "A" plate.  A single head signal with no number plate is just as much a "stop" signal as one with 4 heads.

[dehusman]

Dave-the-Train

I really can't get my head round US practice.

Thanks for the replies.   They've completely thrown me. 

 If you want some really bizzare signal systems, you should check out those in the UK.  They make no sense whatsoever.  8-)

Its just a matter of what you are used to.

Dave-the-Train

Area |(give or take 50 miles) is Chicago.  RR... not sure... something like BRC or EJ&E.  (Can't say I've actually noticed any signals on either but I'm freelancing a bit).  Time is 1980s.  Line A has far-end-of-the-route Metra 1 an hour shuttle.  Line B has one-a-day Amtrak.  (This is all as waffled about in my previous "Chicago 80s" thread).

That makes it real easy.  That makes it fall into GCOR era.  The General Code of Operating Rules can be found on the web so you can read the rules that apply.

I've recalled... APB = Absolute Permisive Block.    I think?    That's scarey weird stuff.   I'd rather go for absolute signals probably with a tower but CTC would be okay.

Actually its not scary at all.  All it means is that when a route is cleared in one direction, all the opposing signals drop to red.  Its what 99.99% of US roads use.  Whenever anybody talks about "ABS" they are actually talking about APB.

It sounds like I might need to wait and get kits to put the heads where they need to be???  One two or three heads?  Okay so an Absolute stop has two reds the lower one of which may be always red... can that one give a "proceed" of some kind if the route is set through the curve of a switch/ the lesser route?

FIRST.  There is no such thing as "absolute stop".  No rule book has an "absolute stop" indication.  There is Stop and there is Stop and Proceed. 

You do not need two heads for a Stop signal.  You need multiple heads to indicate alternate indications other than Stop.

More later.

[cv_acr]

dehusman

cv_acr

That may depend on the signal rules of the road you're modelling. On many roads an absolute stop is Red over Red, so even on a route that doesn't divide or merge through the curved leg of the switch you'd have a 2-target signal, but the bottom light would never be anything but red. You see the same thing at the end of a controlled siding at the trailing end of the switch on the main track. The only possible route is straight through, but the bottom red is required for the absolute stop indication.

It does depend on the rule book since in the rule books with which I am familiar with the number of heads doesn't have anything to do with whether or not its an absolute signal or not.

What makes it an absolute signal in most rule books is the abscence of a number plate or an "A" plate.  A single head signal with no number plate is just as much a "stop" signal as one with 4 heads.

I guess I should have clarified that better (I may have as a result inadvertantly said something inaccurate), although of course, due to the variations the clarification is more complicated. :-)

As Dave H. rightly points out, a single headed signal with round metal plate with an "A" on it mounted below the signal head displays an [Absolute] Stop when Red. The lack of a numberplate is often quoted as well, especially when demonstrating examples of APB signalling on western roads. I'm not sure if this rule in included in Canadian Rulebooks; I've never seen in used in practices. While it is possible to display (Absolute) Stop using a 1-head signal, I've never seen this in practice at any CTC control point or interlocking, although there may be exceptions on other railroads.

I should also have clarified that a signal with 2 or more heads where the heads are mounted vertically all on the same side of the post is an (Absolute) Stop when all lights are Red. In practice, this is the arrangement that I've seen at pretty much any interlocking or control point, where all signals have at least two heads (Note that under Canadian rules these signal may be with OR without number plates. In practice I've never seen one without. This may vary on some US roads according to applicable rules??)

When the top head is staggered over to the other side of the post from the rest, that's generally a "Stop and Proceed [at restricted speed]" signal when all lights are Red.*

* Unless there's a square yellow "R" plate under the signal, which makes the all-Red indication a "Restricting" signal. Pretty common on most intermediate block signals up here on CP and CN.

Confused yet? Following the rules of the road you're modelling are key. Everything Dave H. is correct, he's a guy who definately knows what he's talking about. There's just a lot of variation between different roads, so there could be some variation from the examples I've given depending on the road. (other factors such as other signals on the layout (or lack thereof?) may change some of the specifics as well. If none of the tracks are signalled anywhere else, you might actually just have restricting aspects in all directions as appropriate.)

I'm sure that's sufficiently muddied the waters for you. :-)

[dehusman]

Before we go any further, based on the way the previous picture is labeled this is what I think you are describing:

Is this what we are talking about?  Or is the track arrangement different?

[dehusman]

Or is this what you are talking about?  I omitted the switching lead since its irrelevant for the diamond discussion.

What is the line I have the question about?

The only signal I have a question about are the ones at X.  The one on the blue line will will be two heads and the one on the red line will be one, but the colors depend on whether connection is a signaled, bonded track or not.

All of the signals can display an approach signal if all the mains are CTC.  The two headed signals will display a color over red for normal routes and red over a color for the diverging routes.

Why is approach such a big deal?  All it means is to slow down and prepare to stop at the next signal.  The speed through the turnout /crossover will be specified in the timetable/special instructions based on the size of the switch.

[wjstix]

 For a two-headed signal where two tracks are crossing each other at grade but there are no other route options, as was noted one head will often be a "dummy" which can only show red. Usually that would be the lower head, with the top being red-and-green or red-yellow-green. The problem with single heads in that situation is that a single head block signal is often "permissive" meaning a train doesn't have to stop at it, it just has to slow down enough that it can stop in time if there is something on the track ahead. At a place where two lines cross, you want to be sure everyone understands that it's an "absolute" stop indication that you can't cross until you get the green signal.

In the drawing in the previous post, the X near to the blue line would be at least two-over-two so it could indicate that it's clear thru the crossing (green-over-red) or that the track is set to turn to the right and not go thru the crossing (red-over-green) or a stop (red-over-red).

You could get by with a single head at the other X, but it might be better to add a dummy lower head so that to make clear that trains have to stop there.

BTW re the signal by the question mark in "what is this?" note that before about 1990 signals had to be above and to the right of the track they controlled, it's only been in recent years that signals could be on either side of the track.  

[dehusman]

wjstix

The problem with single heads in that situation is that a single head block signal is often "permissive" meaning a train doesn't have to stop at it, it just has to slow down enough that it can stop in time if there is something on the track ahead. At a place where two lines cross, you want to be sure everyone understands that it's an "absolute" stop indication that you can't cross until you get the green signal.

Once more with feeling.

Under the 1980's GCOR here are ONLY two stop signals.  Stop and Stop and Proceed.  Under GCOR a single red signal on a signal mast with a number plate only displays Stop and Proceed (regardless of the number of heads).  ALL other all solid red indications are just that, Stop.  It is very clear.  Everybody understands that.

And a Stop indication can be crossed without it going to green.  There is a whole list of conditions that permit that in the rules (rules 9.12.1 through 9.12.4).  Everybody understands that too.

If Dave the Train absolutely must put two or three heads on every signal just so people don't get confused, go for the gusto, but they aren't really needed.  Now if the interlocking was a manual interlocking built in the 1920's or 1930's  and then modernized it might have older signals that might have more heads.  Modern thinking is that if a signal with three heads means the same as a signal with two heads as a signal with one head, why add all the complexity if the indication is EXACTLY the same.

[Dave-the-Train]

dehusman

Or is this what you are talking about?  I omitted the switching lead since its irrelevant for the diamond discussion.

What is the line I have the question about?

The only signal I have a question about are the ones at X.  The one on the blue line will will be two heads and the one on the red line will be one, but the colors depend on whether connection is a signaled, bonded track or not.

All of the signals can display an approach signal if all the mains are CTC.  The two headed signals will display a color over red for normal routes and red over a color for the diverging routes.

Why is approach such a big deal?  All it means is to slow down and prepare to stop at the next signal.  The speed through the turnout /crossover will be specified in the timetable/special instructions based on the size of the switch.

Sorry for vanishing.  Between this post and the previous one I got called in to work in a hurry.  Didn't even change until after I got there.

I've been on the go all night - unplanned - so I'd not had any rest yesterday... so I'm shattered.  However you've all put a lot of time in so I'll get back with this now and then zonk out.

This is closer to what I'm up to.  The "What is this" line is about where the dead-end interchange spur would be that Dave H has left  out.  South of that I have marked the approximate location of a parallel switching road.  This will have (or have had) various spurs and loops off it and various docks/platforms.  It willrun right across the normal (south) viewing side of the layout and disappear eastward and westward.  The only connection to the Main tracks I plan to model will be at the east end to the 2nd Main.  From a modelling point of view this will give some switching potential mosty clear of the Main tracks.

Okay...while I was on standby I typed up the following.  I hope that it makes sense.

Sorry… Had to whiz into work.  While I can use my laptop I can’t post…

 

The best thing about the way that this has developed is that it confirms what I have said about UK signalling for years… If you want to get the correct signals you have to look at what the traffic is doing.

 

[By the time I’ve done this and other things Dave H’s second diagram has arrived.  Hopefully what follows answers your questions…]

 

Dave H’s questions.

 

Both tracks across the diamond are main tracks. 

 

I’ve redrawn the schematic and will try to e mail them to you.  Perhaps someone can be kind and post them for me.

 

I have used an east-west orientation only for convenient description.  If the ideas begin to coincide with lines running to different points of the compass this can be changed.

 

I have done two diagrams of the diamond and a third of the track immediately to the east.  Page 1 is the layout I want to model.  Page 2 is the previous layout that has just been replaced due to changes in traffic, rationalisation and possibly change of RR ownership of possibly one or other of the routes here or a nearby route not modelled.

 

[Will have to e mail later.  The difference between 1 and 2 is that there is no direct link between line B and Line A's Second Main (the lower Main Track).  Interchange traffic headed east from line B would have to go past the earlier connection, over the diamond and set back into the dead end spur.  It could then be collected into what was the Eastbound Main which is now the bi-directional 2nd Main.  (Obviously the upper Main was then listed as the Westbound Main).  This ties in with the last posts before this.  having been involved in resignalling and track changes I have a special interest in change.  So I'm interested in what would have been and what would be.  Rather than a complete "all change refit"  I'm interested in a change using essential new track and signals but keeping old stuff in use where possible.  I'm sure that. like us,  RR did this when short of funds].

 

I have not shown any loops or spurs off of the switching line as I don’t have a clue where they might be yet.

 

Next, I now have a question.

 Both lines carry passenger traffic.

           

As the lines are passenger carrying does that mean the RR have to be Class 1 roads?

 

Both lines are signalled.  ‘Cos proper railways are signalled.

 Talking of which… UK signalling is dead easy.   Red means Stop (and stay there).  Everything else is a Proceed Aspect.  (1)

So, meanwhile, back at the fun trains…

 

GOCR  “Read and apply”.    !!!!!  Ever seen the movie “A Few Good Men”?  Everything’s in the manual right?

 At least with our semaphore (and semaphore based) signalling we put our signals where we wanted drivers to Stop so that they didn’t hit things (or get hit).  Even our modern whizzo high tech stuff tells ‘em to Stop… it just does it a bit further away at times.  Plus we have one standard set of semaphores indications and one standard set of colour lights… just ‘cos they come in lots of different shapes… noticing that is just being picky! We don’t have position light Running Signals, multiple heads (any more) and heads jumping around either side of the posts! 

So that’s my excuse/reason for having read pre GOCR and GOCR stuff, being helped out before by Nick… and still having steam coming out of my ears when I look at US signalling… but it is fun! 

 

Like Dave H says… “Is it a main track?  Is it signalled?  …  Are all the lines the same railroad or…”?

 

Actually, re-reading that bit your comment suggests the possibility that if a route is signalled from one RR to a different RR it could mean that the aspect colour could be different?

 

That would be – diverging route set to same RR might get a green but the same track arrangement and line speed diverging route set to a different RR might get a yellow… Yes?/No?

 

See!  I told you your system is complicated you call “ABS” “APB”! No wonder my head explodes! … and then you don’t have “Absolute Stop” but you do have “Stop” and “Stop and Proceed”.  {and then you keep messing about and changing it! ].

 

Reading on I take it that “Stop” means Stop (absolutely) stay there and do not proceed until you get a change of aspect or instruction while “Stop and Proceed” Means Stop, wait a bit and trundle on cautiously so you don’t bump into the back end of a train in front.

 

I do know the logic of your Stop and Proceed.  It results from having massively long lengths of track between signals across a continent while we have short distances on an island.  [Given the diamond with two passenger carrying lines I go for signals that completely, definitely (if not abslutely) tell trains to STOP until they get a green/proceed aspect].

 

Hmm… I was a bit surprised at the idea that two heads for a block signal would be “expected”… at least in CTC.  I’m aware that Block signals way out in the middle of nowhere have single heads.  I’ve seen pics of trains “splitting” the Block signals on Single track – one signal being for East Bound and the other for West on opposite sides of the track – facing opposite ways.  Looks very impressive but not exactly something that would get modelled a lot… is it?

 

So… 1980s Chicago, give or take 50 miles.  Would that be CTC or still a tower/interlocking?  Blue Island seems to have kept a tower – structure – but I know that could have had a CTC panel in it… so then I’m lost again.  Weren’t there lift bridges nearby?  Who controlled those?  (Sorry that’s wandering off).

 

AAARGH!  Laptop just dumped and didn’t do a rescue. 

 

Aargh! With the ideas as well. 

 

The sort of place I’m trying to achieve is a minor “hotspot” / bottleneck.  Somewhere where trains are regulated by definite signal instructions so that the “towerman”/operator/??? can regulate the traffic into the order/sequence that he wants… subject to instructions coming from whoever and the TT (or vice versa).

 

So… I have a preference for a tower by, or at least in sight of, the diamond unless there is a good reason to go for remote CTC.

 

As I understand it small towers could have small (electric) switch panels that controlled both (track) switches and signals electrically in much the same way that a CTC controlled them remotely.  I’m not clear whether small arrangements like this were still called “interlocking” towers or if that term was restricted to mechanical frames?

  

Okay… so I think that what the traffic is doing will go some way to determining the signals required and just what heads which signals get.

 

What we can’t see from the diagrams is the idea that just off to each side of the modelled area there are various other yards. 

The tail tracks on the north side are private industrial tracks on which switchers haul out coal cars to shove them back over coal dumps/drops or into empty car roads at the east end.  this gives the model “switching” action without any messing about coupling and uncoupling on scene.  It also provides for coal drags to arrive from either RR from the west.  this could be why the connection has been altered.

 

South of the line there is a RR owned freight line serving various industries along the south side and at both east and west ends.  I’ve shown a connection across both main tracks to the private coal tracks but this is only a concept at present.  I think that the diamonds required would affect the signals for eastbound trains???

 

Rather than try to invent a whole local geography of RR and yards it is easier to describe the traffic.

 

Line A now has heavy long distance freight that will stay on line A.  The two mains allow hotshots to get round slow stuff in either direction.  From the model point of view this means that a mix of cars can trundle to a stand in (usually) the second main to wait while opposing traffic clears or a hotshot such as a TOFC or Reefer train goes round it.

 

Line A’s own local traffic has reduced to “moderate” with trains from the west dropping off/collecting whole cuts to/from a yard just to the east of the layout.  Traffic for the switching line and local traffic to go into the remaining interchange spur for B line’s local working to collect is worked by the yard’s resident switcher(s).  This can be done via either the switching line or the 2^nd Main depending on what traffic is about.

 

There could be some transfer traffic between this east yard and one or more other specific yards to the west… because I have a pair of MP15DCs.

 

Amtrak zooms straight through on line A… slowly…  some days of the week.

  

Line B has lost most of its long distance freight on the east side but can still get detours.

 

There will be (now that I’ve figured it out) a run-through coal drag from Line B to Line A with empties returning.  This might be bridge traffic for Line B.

 

Line B’s local traffic is reduced east of the diamond.  It may be that they pretty much stop at a yard west of the diamond and come forward as virtually switch jobs. Some heavier jobs may come on with their road engines. Lesser ones may have a switcher or Geep out of the yard.

 

Line B carries end-of-route Metra Bi-Level shuttles.

            (These originate somewhere well beyond the west end of the layout and

            terminate not far beyond the east end.  They do not have a long turn-round

            time at the east end – which makes their there-and-back crossing of the

            diamond quite quick when going east and coming back west. [This is designed

            to affect working of all other traffic over the diamond as these trains are on

                        specific time schedules].

 

I suspect that all this could add up to Line A being CNW – maybe ex Rock Island or CGW????? (which would avoid CNW’s correct side running)– with Line B being ATSF with BN having the run-through/bridge coal train – or vice versa.  This probably plays havoc with the real geography.

 

Then again the RRs could be totally different with the CNW MP15DCs running through…

 

I hope that this lot answers more questions than it creates…

 

That was as far as I'd got after the quoted post. [Plus some edits].

 

Some of what has followed from the above quote confirms the sources of my not understanding.  If you guys can argue about it how am I supposed to get to grips with it?   

 

 (1) If you have a Running Line junction the old semaphore signals tell you which way you are going by the position of the signal left to right across the display.  (left most arm is the left most route through to right most arm is the right most route.  If all the arms are the same height all the routes have the same value.  If the height varies the highest arm is the highest value route).If you have a Running Line junction the “modern” colour light signals tell you which way you are going by adding a line of white lights pointing to the side you are going.  These are usually above the top aspect.  Up 45 degrees left means first route left, 90 degrees left is second route left and down 45 degrees left is third route left.  the same pattern applies on the other side for routes to the right.  A Proceed aspect and no white lights (“feathers”) means you are going straight on.There is no speed indication at all in this.  The signal tells a Driver that he must Stop or he may proceed and which route he is taking.  The Driver is responsible to know his route including the line speeds (and any temporary or emergency restrictions), gradients, curvature, rail head conditions and the effects that the current weather will have on his type and weight of train.There’s none of this messing about with the signals telling Engineers how fast they should run through connections ahead without specifying where they are going. The exception was the Mirfield project and that “didn’t work”. The simple thing is that we have different “logic systems”.  I don’t know whether you would call your system “binary” but I have discussed our system with some technical bods recently and they agreed with me that our system is binary.  Everything is “you can” or “you can’t”.  There is no instruction about “how”.  “How” is left to the Driver. So, if a driver is approaching a four way junction with the main route third from the left and he can see a line of four red aspect semaphores: He can’t go anywhere.  If the first route to the left of the main is set the second semaphore arm from the left (1^st arm to the left of the main route) can be cleared telling him that he can go that way. There are some adjustments to that and things like “What if you only want him to go a short way?” but that is the basic set-up. See!  I told you it was easy! Obviously, as an ex Signalman, I have wanted to tell Drivers exactly where to go on occasions.  The thing to bear in mind is that “What goes around comes around”.  

[Dave-the-Train]

dehusman

And a Stop indication can be crossed without it going to green.  There is a whole list of conditions that permit that in the rules (rules 9.12.1 through 9.12.4).  Everybody understands that too.

Without having my printout of GOCR to hand (or a clue where it's got to) I would guess that the list is like ours and about 24 items long including things like failed signals, failed locking, failed trains etc.  Basically all the times they've come up with when a signal cannot be cleared but you have to get a train or loco(s) past it.  I used to be able to quote the list but I didn't know many who could and there were plenty of people who argued that you couldn't do ones that you could and vice versa.  (I knew one signaller who resolved such an argument with a manager by knocking him out.  When the manager arrived at the other end and came to everyone was convinced he'd slipped and banged his head... so they got him out of the way in an ambulance and got on with the job  Ah!  Those wer happy days!)

 

dehusman

If Dave the Train absolutely must put two or three heads on every signal just so people don't get confused, go for the gusto, but they aren't really needed.  Now if the interlocking was a manual interlocking built in the 1920's or 1930's  and then modernized it might have older signals that might have more heads.  Modern thinking is that if a signal with three heads means the same as a signal with two heads as a signal with one head, why add all the complexity if the indication is EXACTLY the same.

No.  Dave the Train wants to put in the signals needed.

The issue is just what signals might have survived from as far back as the 30s and what new ones would be in place.  then there's a question of affordable rationalisation and requied consistancy/uniformity... bearing in mind that I'm reckoning that an old connection has been removed and a competely new rout put in... so a pretty major change of interlocking will have occured.

On the 3 heads, 2 heads 1 head issue I would entirely agree.  Because our signalling is so much more simple...

 Thanks for all the efforts   I hope I've cleared things up a bit.

[Dave-the-Train]

wjstix

BTW re the signal by the question mark in "what is this?" note that before about 1990 signals had to be above and to the right of the track they controlled, it's only been in recent years that signals could be on either side of the track.  

One thing that I can see is that for earlier signalling the use of a second head could be useful to help distinguish between a signal for the Secon Main and that for the First main for traffic in the same direction.  IIRC someone posted that the 1st main would give Green over red while the 2nd main would give red over green. Something like that would have avoided the norton Fitzwarren smash in the 1940s.

Also I note the required location of signalsto the right or above the line they applied to.  I take it that this is normal practice but that there could be (and were) exceptions where sighting the signal required.  Southern of BR got up to a lot of interesting tricks to avoid "Wrong side" signal siting but since I've escaped into other parts of the country I seem to have fallen over posts in "the wrong place" all over the place.

All this is muddled in my desig by the fact that somewhere in the 80s my track layout has been altered and the A line Main tracks have been altered from directional to bi directional.

 There's nothing like confusing the issue. 

[Dave-the-Train]

Thanks for all yur help everyone.  Have a really great Christmas day.   I'm off to get some sleep before work tonight. 

[dehusman]

Dave-the-Train

 Talking of which… UK signalling is dead easy.   Red means Stop (and stay there).  Everything else is a Proceed Aspect.  (1)

What very few people in the UK seem to realize is that US signals are in many ways EXACTLY the same.  A stop signal means stop and everything else allows you to proceed.

In the GCOR, the stop and proceed indication has been completely eliminated and replaced with "Restricting", no stop required. 

The idea behind stop and proceed was never that it was intended to be a stop and stay.  It was ALWAYS intended to be a signal that caused a train to operate at restricted speed.  It was just felt to be safer to require a stop first, then to proceed at restricted speed.

And just like in the UK if there are problems the dispatcher/control operator/signalman can authorize a train to pass a signal displaying stop.

In 30 years I find it hard to remember a single instance where a crew mistook a Stop for a Stop and Proceed.  Most signal failures by the crews are where they mistake an approach signal for something else or a stop signal for something else or read the wrong signal head.

[nbrodar]

 I borrowed Dave H's drawing and added my thoughts...

All signals are of course Absolute.   This is pre-1985, so all signals must be to the right of or above the track controlled.   We'll ignore the advance/distant signals and just look at the interlocking signals.

This could either be a CTC remote interlocking or a manned tower.  Yes, even when electronic interlocks replaced the mechanical ones, they were still called interlocking towers.

The signal protecting the North approach on RR B only needs to be a single head.   However, it is likely to have a second head that only displays red.  Likewise the RR A Main 1 East signal only needs one head, but I've shown it with two.

RR A Main 2's east signal could be a dwarf between the tracks (as in the main drawing), on a dual high mast (the alternate drawing) or a signal bridge.

RR A's West and RR B's South approaches should be self explanatory.  I've also shown a dwarf signal protecting the exit of the Interchange track.  

Nick

[dehusman]

Both lines carry passenger traffic.As the lines are passenger carrying does that mean the RR have to be Class 1 roads?

The ‘class’ of the railroad is based on revenue, has nothing to do with what the railroad does.  The “class” of the track is based on the speed permitted based on the maintenance tolerances and except for “excepted” track (the lowest category) has nothing to do with what traffic is run.The ‘class’ of the train is dependent on the timetable schedule but was done away with by the GCOR and in any case, any era, would have been superceded by the CTC. 

Both lines are signalled. ‘Cos proper railways are signalled.

Great, but what about ALL the tracks leading into the interlocking.  What about them. 

At least with our semaphore (and semaphore based) signalling we put our signals where we wanted drivers to Stop so that they didn’t hit things (or get hit).

 Exactly the same with US signals. 

Plus we have one standard set of semaphores indications and one standard set of colour lights… just ‘cos they come in lots of different shapes… noticing that is just being picky! We don’t have position light Running Signals, multiple heads (any more) and heads jumping around either side of the posts!

 

One thing to remember is that virtually any one of the US Class1’s (or both of the Canadian roads together) by themselves, have as much mileage under any one rule book as the entire UK rail system.  If you count all the GCOR roads together there is probably 3 times the miles of railroad under one rulebook as the UK. 

 

Actually, re-reading that bit your comment suggests the possibility that if a route is signalled from one RR to a different RR it could mean that the aspect colour could be different?

 Signal systems are meant to control speed, to give the train crews advance warning of a stop.  So to do that, the signal system has to know whether any of the next two or three signals are at stop.  If you are signaling onto another railroad, then the signals on your railroad may not know what the indications are on the other railroad.  So from your railroad’s point of view the other railroad is “dark territory”.  If its all one railroad, then its not a problem. 

  That would be – diverging route set to same RR might get a green but the same track arrangement and line speed diverging route set to a different RR might get a yellow… Yes?/No?

No. Approach means that the next signal displays a signal that requires a stop.   When you are running a 10,000 ton train, you need a couple miles warning to slow the train down safely.  If you don’t know what the signals are on the other railroad, the best you will get is “Low” or “Restricting”. 

See! I told you your system is complicated you call “ABS” “APB”! No wonder my head explodes! … and then you don’t have “Absolute Stop” but you do have “Stop” and “Stop and Proceed”. {and then you keep messing about and changing it! .

 And some roads call CTC TCS, but it doesn’t change one rule or how one thing is done on the railroad.  Po-tay-toe, po-tah-toe, big whoopee.  As far as “absolute stop” goes I can’t help it if model railroaders make up signal indications and then you get confused when you can’t find the make believe indications in the rule book. 

Reading on I take it that “Stop” means Stop (absolutely) stay there and do not proceed until you get a change of aspect or instruction while “Stop and Proceed” Means Stop, wait a bit and trundle on cautiously so you don’t bump into the back end of a train in front.

 Stop means stop. The purpose of a stop and proceed signal is to get the train down to restricted speed.  The rules require the train to stop before proceeding at restricted speed. 

  I do know the logic of your Stop and Proceed. It results from having massively long lengths of track between signals across a continent while we have short distances on an island.

 Restricted speed controls the movement between signals.  What the STOP and proceed does its make sure the train is moving at a restricted speed.  Since you have to STOP the train before entering the block at restricted speed, you definitely won’t be barreling in there at a higher speed.  The stop is a way control the speed.  It is not intended to hold the train and it isn’t used in situations where a STOP is required.  It is used in conditions where restricted speed is required.For some reason the stop and proceed signal confuses people in the UK.  You guys stop reading at the “stop” part and never think about the “and proceed” part.  

I was a bit surprised at the idea that two heads for a block signal would be “expected”… at least in CTC. I’m aware that Block signals way out in the middle of nowhere have single heads. I’ve seen pics of trains “splitting” the Block signals on Single track – one signal being for East Bound and the other for West on opposite sides of the track – facing opposite ways. Looks very impressive but not exactly something that would get modelled a lot… is it?

 The number of heads depends on what indications are being given.  If you want an indication that requires two heads then the signal will have two heads. Very few people have a layout big enough to get intermediate signals.  So most model signal systems are an approximation of a real signal system and don’t do what real system does.  Yours won’t either.  It will be a model of a system. 

So… 1980s Chicago, give or take 50 miles. Would that be CTC or still a tower/interlocking?

Yes.An interlocking is the track arrangement and signal system that only permits movements on one route at a time.  CTC is a signal system.  So regardless of the signal system, you will have an interlocking. 

Blue Island seems to have kept a tower – structure – but I know that could have had a CTC panel in it… so then I’m lost again. Weren’t there lift bridges nearby? Who controlled those?

Interlockings can be manual or automatic.  Automatic interlockings are mostly simple diamonds and an electronic circuit lines the signals.  Manual interlockings can have somebody in a tower or can be remotely operated where the dispatcher or control operator is not located at the interlocking.  Your track arrangement requires a manual interlocking. 

So… I have a preference for a tower by, or at least in sight of, the diamond unless there is a good reason to go for remote CTC.

So put in a tower.  It makes no difference in the signals or operation other than they have to talk to a control operator rather than the dispatcher (unless the dispatcher is located int eh tower and is the control operator).  No difference whatsoever. 

What we can’t see from the diagrams is the idea that just off to each side of the modelled area there are various other yards.

  Immaterial. The only thing that matters are the tracks and switches inside the outer signals of the interlocking, and whether the routes coming into the interlocking have a block signal system on them.  If the tracks aren’t a part of the interlocking (such as a switching lead) they don’t matter.   

The tail tracks on the north side are private industrial tracks  <snip> That was as far as I'd got after the quoted post.

 Really doesn’t matter. 

Some of what has followed from the above quote confirms the sources of my not understanding. If you guys can argue about it how am I supposed to get to grips with it?

Pick a rule book.Pick an era.Give us a drawing of the track arrangement.Right now we are all guessing on what tracks are what and what rules you want to use.We are arguing because you haven’t defined what you are doing and what the conditions are. 

(1) If you have a Running Line junction the old semaphore signals tell you which way you are going by the position of the signal left to right across the display. <snip> The simple thing is that we have different “logic systems”.

 Jeez what a confusing mess.  Must have been designed by your government. 

I don’t know whether you would call your system “binary” but I have discussed our system with some technical bods recently and they agreed with me that our system is binary. Everything is “you can” or “you can’t”.

 The GCOR has one Stop indication and everything else is a proceed with limitations on speed or what they should be prepared to do at the next signal. 

There is no instruction about “how”. “How” is left to the Driver. So, if a driver is approaching a four way junction with the main route third from the left and he can see a line of four red aspect semaphores: He can’t go anywhere. If the first route to the left of the main is set the second semaphore arm from the left (1^st arm to the left of the main route) can be cleared telling him that he can go that way. There are some adjustments to that and things like “What if you only want him to go a short way?” but that is the basic set-up. See! I told you it was easy!

 So if the third signal on left has feather and the second signal on the third route has its arms at 45 degrees you can go? What a mess.  Just put one signal over the track the driver is on and tell him to go or not and how fast he can go based on what he has to do at the next signal. 

Enough arguing about which signal system is more confusing to people who don’t understand it.

 

Simple answer, make each signal with more than one route a two headed signal.  Make every signal with only one route a single headed signal.  On the two headed signals make it display green over red when the switches are lined for the straightaway route, and red over green when lined for other than straightaway route.  Red over red when a switch is lined against the movement or a conflicting route is lined.  Single head signals green if the route if the switches are lined for the route and red if the switches aren’t lined for the route or there is a conflicting route lined.

 

[BRAKIE]

Guys,remember..A stop and proceed signal is worthless at a interlocker especially with a diamond or connector track..Those would be absolute signals.

 

Also there won't be a need for a signal on a interchange track since the cars would be shoved into the interchange in either direction and the cars would be stopped just a tad short of the fouling point..

 

Now if that transfer track was a connector track then a signal would be needed at both ends..

[dehusman]

Here is a simple primer on GCOR signals.  If the top head is green then its clear.  Proceed at maximum speed.  If the top head is yellow then it is an approach signal.  The purpose of an approach signal is to start slowing down the train in preparation for a stop or speed reduction ahead.  So depending on the distance to the restriction and the maximum speed on the line, there are a variety of approach signals. The most common are:Advance Approach that tells the train to proceed, prepared to stop at the second signal, immediately reducing speed to 40 mph.  It will have either the top yellow flashing or the second head solid green.Approach diverging which has two solid yellows, proceed to advance on the diverging route at the speed of the turnout.Approach with one solid yellow, proceed prepared to stop at the next signal, freight reduce speed to 30 mph, passenger to 45 mph.Approach restricting which has a lunar head, proceed prepared to pass the next signal at 15 mph. There are also two “high speed” approaches used in those territories where there are high speed trains (70 mph and higher).Approach clear 60 with the second head a flashing green, proceed passing the next signal at 60 mph.Advance approach passenger, same as advance approach, only with a “C” plate on the mast.  Freight slows to 40 mph and passenger slows to 60 mph.  If the signal has more than one head and the top head is red, it’s a diverging signal, governing movement over a diverging route.  There are two diverging clears:Diverging Clear Limited has a flashing green on the second head, proceed on diverging route, not to exceed 40 mph.Diverging Clear has a solid green on the second head, proceed on diverging route at the prescribed speed.  Then there are the diverging approaches.Diverging Advance Approach that tells the train to proceed at the prescribed speed on the diverging route, prepared to stop at the second signal, immediately reducing speed to 40 mph.  It will have the second head  yellow flashing.Diverging Approach Diverging which has two solid yellows below a red (and no number plate), proceed on diverging route at prescribed speed prepared to advance on the diverging route at the speed of the turnout.Diverging Approach with one solid yellow on the second head, proceed at the prescribed speed on the diverging route prepared to stop at the next signal, freight reduce speed to 30 mph, passenger to 45 mph. There are also a passenger diverging approach used in those territories they want the passenger trains at a higher speed.Diverging Advance Approach Passenger, same as Diverging Advance Approach, only with a “C” plate on the mast.  Freight slows to 40 mph and passenger slows to 60 mph.  There are two signals where the movement away from the signal is at restricted speed.Restricting is a lunar head with or without red heads, or a flashing red.  Proceed at restricted speed, not exceeding prescribed speed through the turnout.  NOTE: NONE of the above indications change with the presence of a number plate (except Diverging Approach Diverging).    Stop and Proceed, all lit heads are red with a number plate or a “G” plate.  Stop then proceed at restricted speed.  Finally Stop, all lit heads are red without a number plate.  Stop.  Any signal with a green in it is 40 mph or track speed (if less than 40).Any signal with a yellow in it is some version of Approach.  Any signal with a flashing yellow in it is 40 mph or track speed (if less than 40).Any signal with a yellow and color other than red doesn’t require a stop at the next signal.Any signal with a lunar requires restricted speed.  The vast majority of railroads territories use the same set of aspects.  Not all aspects are used on all territories.  99.9% of railroad employees will never see all the various aspects of the indications, let alone all the indications.   

 

[dehusman]

BRAKIE

Guys,remember..A stop and proceed signal is worthless at a interlocker especially with a diamond or connector track..Those would be absolute signals.

Exactly.

Also there won't be a need for a signal on a interchange track since the cars would be shoved into the interchange in either direction and the cars would be stopped just a tad short of the fouling point.. Now if that transfer track was a connector track then a signal would be needed at both ends..

Exactly.  That's why I keep asking what the tracks are for.  If they are not tracks with a block signal system on them then there would not be a signal into them and probably not a signal out of them.

[Dave-the-Train]

dehusman

Here is a simple primer on GCOR signals.·         If the top head is green then its clear.  Proceed at maximum speed. ·          If the top head is yellow then it is an approach signal.  o    The purpose of an approach signal is to start slowing down the train in preparation for a stop or speed reduction ahead.  §  So depending on the distance to the restriction and the maximum speed on the line, there are a variety of approach signals.·          The most common are: o    Advance Approach that tells the train to proceed, prepared to stop at the second signal, immediately reducing speed to 40 mph.  §  It will have either the top yellow flashing or the second head solid green.o    Approach diverging which has two solid yellows, proceed to advance on the diverging route at the speed of the turnout.o    Approach with one solid yellow, proceed prepared to stop at the next signal, freight reduce speed to 30 mph, passenger to 45 mph.o    Approach restricting which has a lunar head, proceed prepared to pass the next signal at 15 mph.o     There are also two “high speed” approaches used in those territories where there are high speed trains (70 mph and higher).o    Approach clear 60 with the second head a flashing green, proceed passing the next signal at 60 mph.o    Advance approach passenger, same as advance approach, only with a “C” plate on the mast.  Freight slows to 40 mph and passenger slows to 60 mph.  ·         If the signal has more than one head and the top head is red, it’s a diverging signal, governing movement over a diverging route.  o    There are two diverging clears: §  Diverging Clear Limited has a flashing green on the second head, proceed on diverging route, not to exceed 40 mph.§  Diverging Clear has a solid green on the second head, proceed on diverging route at the prescribed speed.  o    Then there are the diverging approaches.Diverging §  Advance Approach that tells the train to proceed at the prescribed speed on the diverging route, prepared to stop at the second signal, immediately reducing speed to 40 mph.  It will have the second head  yellow flashing.Diverging §  Approach Diverging which has two solid yellows below a red (and no number plate), proceed on diverging route at prescribed speed prepared to advance on the diverging route at the speed of the turnout.§  Diverging Approach with one solid yellow on the second head, proceed at the prescribed speed on the diverging route prepared to stop at the next signal, freight reduce speed to 30 mph, passenger to 45 mph. o    There are also a passenger diverging approach used in those territories they want the passenger trains at a higher speed.§  Diverging Advance Approach Passenger, same as Diverging Advance Approach, only with a “C” plate on the mast.  Freight slows to 40 mph and passenger slows to 60 mph.  o    There are two signals where the movement away from the signal is at restricted speed.§  Restricting is a lunar head with or without red heads, or a flashing red.  Proceed at restricted speed, not exceeding prescribed speed through the turnout.  ·         NOTE: NONE of the above indications change with the presence of a number plate (except Diverging Approach Diverging).    ·          ·         Stop and Proceed, all lit heads are red with a number plate or a “G” plate.  o    Stop then proceed at restricted speed.  ·         Finally Stop, all lit heads are red without a number plate.  o    Stop.  ·         Any signal with a green in it is 40 mph or track speed (if less than 40).·         Any signal with a yellow in it is some version of Approach.  ·         Any signal with a flashing yellow in it is 40 mph or track speed (if less than 40).·         Any signal with a yellow and color other than red doesn’t require a stop at the next signal.·         Any signal with a lunar requires restricted speed.  ·          ·         The vast majority of railroads territories use the same set of aspects.  ·         Not all aspects are used on all territories.  ·          99.9% of railroad employees will never see all the various aspects of the indications, let alone all the indications.   

Thanks Dave.

Hope you don’t mind one or two bullet points.  I think I got the cascade right.

Edit:  indenting format didn't post   So I coloured them in.

Edit 2:  Still didn't format very well.   I've checked though: if anyone wants this as a nice cascade just copy it into a word doc and hit Enter before each bullet - then tab in as appropriate... You probably know this...

 

[cv_acr]

Hmm… I was a bit surprised at the idea that two heads for a block signal would be “expected”… at least in CTC.  I’m aware that Block signals way out in the middle of nowhere have single heads.  I’ve seen pics of trains “splitting” the Block signals on Single track – one signal being for East Bound and the other for West on opposite sides of the track – facing opposite ways.  Looks very impressive but not exactly something that would get modelled a lot… is it?

Here's a specific example to illustrate.

Consider the last block signal before your interlocking on A main track 2. Because the interlocking signal may be displaying a slow speed indication, then this block signal must be capable of displaying an "Approach Slow" indications which is Yellow over Yellow, so it needs two heads. On track 1 the last block signal would be a single head since it only needs to display Stop & Proceed, Clear or Approach. Not Approach Medium or Approach Slow (or Approach Diverging depending on the rulebook).

So, if a driver is approaching a four way junction with the main route third from the left and he can see a line of four red aspect semaphores: He can’t go anywhere.  If the first route to the left of the main is set the second semaphore arm from the left (1^st arm to the left of the main route) can be cleared telling him that he can go that way. There are some adjustments to that and things like “What if you only want him to go a short way?” but that is the basic set-up. See!  I told you it was easy!

So if a train is arriving at an interlocking, regardless of what track it is on it has to look at _all_ the signals to try to figure out what it's doing? How is that easy? N. American practice is each track has its own signal, and that signal is located beside or above the track it controls. No figuring out specific routes or anything since the dispatcher or tower operator sets all those switches for you. The signal just tells you what speed to take past this signal and what speed to approach the next.

[cv_acr]

Dave-the-Train

wjstix

BTW re the signal by the question mark in "what is this?" note that before about 1990 signals had to be above and to the right of the track they controlled, it's only been in recent years that signals could be on either side of the track.  

One thing that I can see is that for earlier signalling the use of a second head could be useful to help distinguish between a signal for the Secon Main and that for the First main for traffic in the same direction.  IIRC someone posted that the 1st main would give Green over red while the 2nd main would give red over green. Something like that would have avoided the norton Fitzwarren smash in the 1940s.

If you're thinking of a single signal controlling traffic on two parallel tracks at the same time, absolutely not. Each signal only controls _one_ track. The example you're referring to is where one track splits into two; and a train taking the diverging route would get a different indication. But there's only one track at the point where the signal is located. It can't give indications for two different tracks at the same time. Each signal can only govern one track and every track has its own signals, located where appropriate. If I approach an interlocking on the right track and there's a green light on the left signal, that means nothing to me because that signal does not apply to my track.

Also I note the required location of signalsto the right or above the line they applied to.  I take it that this is normal practice but that there could be (and were) exceptions where sighting the signal required. 

Yes this was normal practice. Where there were multiple tracks, signals would usually be mounted on bridge structures so that each signal was above and slightly to the right of the track it governed. In situations where this was absolutely not possible, they would be specifically noted in employee documentation. (I have a few Canadian Pacific timetables from the 1970s and 1980s, and for each subdivision that any signalling, there a short section in the footnotes indicating "The following signals are located to the LEFT of the track they govern" with a list of the signal numbers.)

All this is muddled in my desig by the fact that somewhere in the 80s my track layout has been altered and the A line Main tracks have been altered from directional to bi directional.

That doesn't really matter - the interlocking would have been rebuilt to take into account what is possible _now_. The entire plant may have been completely upgraded and replaced if the modifications were particularly significant. (When CN put a third track into Bayview Junction, they also combined the interlocking with the adjacent Hamilton West interlocking and replaced _all_ of the signals involved with new ones. Some of them had to be installed in completely different locations due to the track changes. Point is, there's nothing left of the original signals at that location.)

[Dave-the-Train]

Dave-the-Train

 Talking of which… UK signalling is dead easy.   Red means Stop (and stay there).  Everything else is a Proceed Aspect.  (1)

dehusman

What very few people in the UK seem to realize is that US signals are in  many ways EXACTLY the same.  A stop signal means stop and everything else allows you to proceed.

including a "Stop and Proceed" and a Stop Restricting... except that you don't stop for that...    ... "In the GCOR, the stop and proceed indication has been completely eliminated and replaced with "Restricting", no stop required. "

Without wishing to be too rude this is like an argument with the wife... You've just repainted everything exactly the same colour but she still has to have new curtains because the existing ones don't match any more. 

 I had this "difference of opinion" with some printworkers when I did some safety training.  On the railway a "Shut Down" switch stops everything dead; end of story.  They just could not see that a "Shut Down" switch couldn't allow you to edge part of the machine along... despite the fact that they'd all seen fingers and even hands crushed.

I think that the difference might be described as one of philosophy.  Maybe a bit like one person being high church and another low church.  We're talking about the same thing, with the same words but seeing different perspectives.

What I really want to do is understand the US system enough to model it well.

 

dehusman

The idea behind stop and proceed was never that it was intended to be a stop and stay.  It was ALWAYS intended to be a signal that caused a train to operate at restricted speed.  It was just felt to be safer to require a stop first, then to proceed at restricted speed.

  I've got that

dehusman

And just like in the UK if there are problems the dispatcher/control operator/signalman can authorize a train to pass a signal displaying stop.

  Umm   That could be because we got the original system from Westinghouse...  Including that where a Driver got stopped for more than five minutes on an automatic signal and couldn't contact the signalman at all he could sound a warning and proceed with caution past the signal at red... Now what does that sound like?