Dave-the-Train dehusmanWhat 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. "
dehusmanWhat 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. "
It's called "Restricting" not "Stop Restricting".
"Stop" is stop.
"Stop and Proceed" is stop and then proceed at restricted speed.
"Restricting" is just proceed at restricted speed, no stop required. Note that the word "Stop" is not in the name of the indication at all here.
Chris van der Heide
My Algoma Central Railway Modeling Blog
dehusman 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.
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.
Thought I'd answered that...
Okay, what they are for.
RR A has a single main which becomes 1st and 2nd main. These are signalled (i.e. have a block system in force - don't signals and block systems go together - except maybe for Train Order Boards but I've nowhere mentioned TOs). The traffic (what they are used for) is freight and passenger.
RR B has a single main. This is signalled (i.e. has a block system in force - can you have a block system witjhout signals to denote the limits of each block?). The traffic (what they are used for) is freight and passenger.
There is a linking track which Brakie says will be signalled - which I expected. This is also freight and passenger.
There are coal tracks to the north which have been declared irrellevent to the Interlocking - which I can see.
There is a switching track to the south and a short remaining interchange spur. Both of these connect to the 2nd Main. These are used for interchange and local traffic - mostly in purely switching moves. I can see that they are not going to need signals on masts in the same way as the main tracks... but it seems to be suggested that they don't need any signals at all... ???
From my perspective that is odd - because we divide our track into "Running Lines" - which would be the Main Tracks in this example.- and "non-Running Lines - which would be the coal tracks, interchange spur and switching track. We go further and provide derails or drop offs between all Running tracks and Non running tracks so that nothing can escape from a spur or similar when it shouldn't. It's reckoned that dropping it in the dirt is better than it getting out into the path of anything on the move (potentially doing 125mph). In the majority of cases the route into a non-Running Line and back out from it will be signalled with its own specific indication - this is interlocked to the derail or drop off so that a false proceed can't be given.
For a facing connection the equivalent in signal types that we would use could be a single head (401) for the main track and a dwarf for the diverging route. Then there would be a dwarf to come back out if that move would be regularly made - as with a blind spur.
All the switches have to "prove" to the correct position to allow the appropriate signal to be cleared. Once the signal is cleared the switches are locked until the signal is replaced. As I understand it this is much the same... as per when an electrically locked ground throw is released the protecting signals will either already be at Stop or will go to Stop... and stay there until the throw is given back to normal control/locked.
I can see that, even with a manned tower right by it the throw into the interchange spur could be on the ground in that way... but if it is a move would have to be talked by the protecting signal on the 2nd Main... wouldn't it?
OR...does a move to go into the spur move past the signal at a proceed aspect (which would be?) and then unlock the throw on the ground with the crew on the ground hand signalling the Engineer to make the next move...?
To me that would/could mean locking up the RR B Main by having the RR A 2nd Main signal cleared and then the track in front of it including all of the link occupied. This would be an unecessary tie up of the RR A Main to me.
Something similar goes on for the switching track.
I hope this makes sense!
dehusman Pick a rule book.Pick an era.Give us a drawing of the track arrangement
Pick a rule book.Pick an era.Give us a drawing of the track arrangement
Um? Track layout given. You've specified GCOR, which is fine. The location is Chicago... somewhere with Metra - potentially ex Rock Island track. The date is 1980-89... probably 1986.
.
cv_acr 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.
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.
Oops! Sorry I didn't mean on signal for two tracks. Imeant that the display on the signal for the 1st Main would be significantly different from the nearby seperate/individual signal for the 2nd Main.
I take your points about signal mast (or bridge) and head location and the signalling having been modified to go with the existing track plan. Thanks.
As for our signals being awkward...
They were invented by entrepreneurs and paid for by private companies. A lot of them were in use when the N American roads were using Train Orders and smoke signals... which isn't being rude because I have read in an old US source that when a train struggled (running TO) with a train following they would put oily cotton waste in the firebox to make their smoke black as a warning of where they were... in addition to the conductor throwing out torpedoes as he went along. The (Victorian) government didn't even want to bring in things like clean water laws if it could avoid it... a vast change from today. There was a logic to non-intervention in how railway things were done... everything was being invented, it wasn't clear what the safe, let alone the best, way of doing it would prove to be... PLUS not specifying a single, particular design avoided monopoly and stifling inovation. I think that the ISB (?) got started on regulating RR standards about the same time as our Board of Trade gained a very open regulating hand. All the BoT really required was that a system cvould be shown to be basically safe.
As for signal indications...
The way things are laid out means that it is unusual for a Driver to come up to a large range of signal displays except at large junctions and terminals. Even then the tracks are organised so that a train will be routed over by stages. This is one reason that our layouts are so distinct from almost everyone elses - except the ones we exported. In those complex situations there will be speed restrictions/
It is surprisingly easy to pick out which signal you need to read. It's sort of like picking out the sign you need on the Interstate... actually it's far better than that! If, as Dave H has suggested, you got two indications on the signals applying to one track the Driver would stop because a false indication is a "STOP" indication. In 30+ years I have seen probably less than half a dozen false indications... It's a swine to try and get a picture for training purposes! A "wrong" indication - which is any indication that is not clear for any reason - is also a "STOP" indication.
All that applies to the old systems with semaphore that have been largely replaced. I have pics of US semaphore that also used the same "position value" system (plus 3 aspect indication) and they are just as spectacular and complex at first sight as ours. I'll see if I can dig out a pic. Some of the "Union" terminals with puzzle switches in the approach had amazing arrays of semaphore signals.
Our modern colour light is all single head (multiple aspect). While our line speed is still held to 125 the latest stuff is set up for 140MPH running.
One thing I don't understand. Why does our system get "described" as out-of date" / "not as good as the US" while France's, Germany's etc systems that are all different again are not? Both those countries had fully State railways long before we Nationalised... and that did not put the railways into either state ownership or control... unfortunately it did make it easier for politicians to poke their noses in... but I believe that US governement input at both Federal and State level gets blamed for a whole list of RR woes...
Hope you all had a good Christmas
BRAKIEAlso 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..
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..
I've been on multiple spurs off Main Tracks protected by signals, especially if said spur exits the main within the limits of an interlocking. With manual switches no less. The signal gives you permission to open the switch and proceed. If access to this track is controlled by an operator controlled switch and derail, you'd need a signal to proceed off it.
Of course, I've also been in any number of spurs without signal protection.
cv acrAlso 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.)
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.)
Until 1985, any signal location other then to the right or above required an FRA waiver. All waivered signals were required to be listed in the ETT/SI. Unless conditions made it absolutely impossible, it was always easy to engineer a way to have the signals above or to the right, rather then apply for the waiver. The CNW, which ran left handed, has some spectacularly engineered signal bridges to keep the signals above and right of the tracks.
Nick
Take a Ride on the Reading with the: Reading Company Technical & Historical Society http://www.readingrailroad.org/
Hi Nick Hope you had a good day.
So, just to be really awkward (for a change) I could have the connection from 2nd Main to the switching road directly on the Tower with a signal to go in and another to go out... but I could also have an electrically locked ground throw to go into the (relatively little used) interchange spur... with no signal? Would the spur also have a derail - let's assume that it is flat - would this be electrically locked or just a padlock?
Thanks
In fact a very big thanks to everyone who ihas put time and effort into this. I'm learning a lot.
nbrodar Until 1985, any signal location other then to the right or above required an FRA waiver. All waivered signals were required to be listed in the ETT/SI. Unless conditions made it absolutely impossible, it was always easy to engineer a way to have the signals above or to the right, rather then apply for the waiver. The CNW, which ran left handed, has some spectacularly engineered signal bridges to keep the signals above and right of the tracks.
The CP timetables I have seem to have an average of about half a dozen signals on each subdivision in either direction that are listed as being located to the left. Then again, these are all located in Canada so the FRA is totally irrelevant. :-)
The rules are still similar, but the FRA has no jurisdiction outside the United States.
Dave-the-Train Hi Nick Hope you had a good day. So, just to be really awkward (for a change) I could have the connection from 2nd Main to the switching road directly on the Tower with a signal to go in and another to go out... but I could also have an electrically locked ground throw to go into the (relatively little used) interchange spur... with no signal? Would the spur also have a derail - let's assume that it is flat - would this be electrically locked or just a padlock? Thanks In fact a very big thanks to everyone who ihas put time and effort into this. I'm learning a lot.
What do you mean by switching road? Are you just referring to railroad "B" or a different track here?
If you're talking about the main connection from A to B, you'd just have the main signals guarding the entrance to the interlocking in either direction. Don't need anything in between. (That's assuming it's actually a running connection trains trains might use to actually switch from one line to the other. Even if they're rarely used, they sometimes still exist at some diamonds to allow the connection between 2 different railroads in the event detours are necessary. This depends on the local geography and routing of the lines.) If it's a transfer track that always/often has cars parked in it, the portion where cars are left standing can't be part of the interlocking, so you'd need dwarf signals (probably) on either end to connect it to the interlocking. Or manual, electrically-locked switches and derails at either end.
Most industrial spurs have derails on them (locked with a railway padlock), whether the main territory is signalled or dark. A car derailing on the spur is far preferable to rolling out on the mainline and getting hit by another train at speed.
cv_acrThe CP timetables I have seem to have an average of about half a dozen signals on each subdivision in either direction that are listed as being located to the left. Then again, these are all located in Canada so the FRA is totally irrelevant. :-) The rules are still similar, but the FRA has no jurisdiction outside the United States.
Doh! I should have guessed when you said CP!
There is a switching lead "south" of RR A mains that Dave H omitted from his drawing. On Dave T's original drawing RR A Main 2 and the switching lead connected a little "east" of the interlocking.
Dave-the-TrainI could have the connection from 2nd Main to the switching road directly on the Tower with a signal to go in and another to go out... but I could also have an electrically locked ground throw to go into the (relatively little used) interchange spur... with no signal? Would the spur also have a derail - let's assume that it is flat - would this be electrically locked or just a padlock?
I could have the connection from 2nd Main to the switching road directly on the Tower with a signal to go in and another to go out... but I could also have an electrically locked ground throw to go into the (relatively little used) interchange spur... with no signal? Would the spur also have a derail - let's assume that it is flat - would this be electrically locked or just a padlock?
Dave, I survived Christmas dinner at my in-laws.
Yes you could have another set of crossovers within this interlocking leading to the switching lead. The already indicated signals would handle entering the switching lead, but yes you need another signal to control the cross from the lead back to the main. Assuming operator controlled switches.
The interchange spur could have an manual switch with an electric lock. A derail is a definite. While the derail would probably only have a RR padlock, it would be connected to signal system (as would the switch) as to shunt the circuit when the derail is off (at least this is my experiance with derails leading to signaled main track.)
nbrodarThe interchange spur could have an manual switch with an electric lock. A derail is a definite. While the derail would probably only have a RR padlock, it would be connected to signal system (as would the switch) as to shunt the circuit when the derail is off (at least this is my experiance with derails leading to signaled main track.)
This is why I want Dave-the-Train to publish an actual drawing of what he is doing. I'm not sure what he is describing. Is it really two completely different railroads or two different subdivisions of the same railroad. I can't tell from the way he describes it. If its the same railroad what is he interchanging with?
He is looking for one difinitive way to do things but there really isn't since the interlocking could have been built or rebuilt any time in the last 100-125 years. He hasn't said whether he wants leaving signals or just entering signals.
Since he doesn't want approach signals or indications he should just KISS and put a single head signal any place there is one route and a two head signal anyplace there is more than one route. Then make the normal route for any signal a clear or stop and and any diverging route a diverging clear or stop. Any track that is used to hold cars gets a derail. Tracks with derails don't get a leaving signal. Don't worry about leaving signals. He can put as much interlocking as his circuits and controls can stand.
Dave H. Painted side goes up. My website : wnbranch.com
Sorry about the lack of improved published diagram. The new ones don't show much more than Nick has already posted for me... because there isn't much more. I had to go from work to home/post what I had/to sleep and back to work yesterday. (saved having to be nice to anyone! )
The lines are, as I have said, two distinct RR that cross at garde. They used to make a limited interchange via a short spur, This has been amended to a direct connestion used by a through working of bridge traffic coal from beyond B onto A.
The switching track is track parralel to the south side of A road's 2nd Main east of the diamond and B road west of the diamond. It probably belongs to A road. It has both in-use and redundent loops and spurs off the south side of it - in theory at least. As I've said it is there to provide the model with somewhere for a switcher and cut of cars to trundle about clear of the main tracks.
The switching track has a connection to the 2nd Main so that I can achieve some run-round movements between the west end of the 2nd main and tracks off scene at the east end.
I'm not actually looking for a definitive way of signalling the set-up. I know that there is no such thing. I know that with exactly the same track layout the same company will signal six different locations six different ways... plus those ways may change over the years as traffic, signalling equipment and operating methods change. Also that different combinations of companies will make the variety even greater.
However I would still like it confirmed or denied that at a grade crossing of two companies it is the last one in that has to provide the equipment, manpower and maintenance...
It's not that I don't want approach signals but that there simply isn't length in the modelled area to fit them in... so I thought that not dealing with them would keep things stupidly simple. If they won't be modelled is there any reason that I need to know about them?
I could suggest that all three eastbound signals protecting the diamond would be the approach signals for the yard immediately off scene to the east... but I haven't so far because we have been getting tangled up enough as it is.
One thing that I have figured out has been that Nick has referred to "north" or "east" signals by which he means "northbound" or "eastbound". That is reversed to what I would usually do... although we don't usually identify signals by compass points when we do a north signal would be one at the north end of the track layout or on the north side of a structure included in the name. Yet another example of doing the same thing differently.
Similarly I have not mentioned leaving signals because they won't be modelled.
So now i've been persuaded to mention them...
At one time I would expect that the yard to the east would have had its own tower close to the main connections between the Main tracks and the yard tracks. With modernisation that would probably have been rationalised so that the tower at the diamond also looks after those connections remotely.
With the diamond and yard entrance being so close I would expect that the signals protecting the diamond would always have been the approach signals (or equivalent) for the yard. Also I would expect westbound signals protecting the yard exit tracks and esit signals from the yard to be approach signals for the diamond.
Got to go. I'll send Nick the new diagrams later and, if he's kind, he'll post themn fopr me.
Have a nice day
Dave-the-Train However I would still like it confirmed or denied that at a grade crossing of two companies it is the last one in that has to provide the equipment, manpower and maintenance...
Maybe. Originally yes, but after 50-100 years maybe no. Basically your choice (just like the real railroads).
All of those references are used here, just depends on who is talking, what their reference is.
The tower would control an interlocking on the main track, not the yard itself. In US practice yard tracks are "dark". If the yard is railroad A and the diamond tower is railroad B then railroad A would keep control of the "yard" tower. If railroad A controlled the diamond tower then railroad A might consolidate the two.
Here we go with Dave T's new and improved sketches...
The gray lines are a little hard to see, but there are switching leads to the north and south of mains
And continuing east to see how the switching leads intersect with the mains
Dave-the-Train At one time I would expect that the yard to the east would have had its own tower close to the main connections between the Main tracks and the yard tracks. With modernisation that would probably have been rationalised so that the tower at the diamond also looks after those connections remotely.
Yes indeed, if RR A operates the tower. Depending on traffic levels, they could also be manual electric lock switches. But if there is any type of volume between the yard and main, they are probably remote controlled from the tower.
Yes. Although, several places I have worked, the exit signals from the yard only displayed STOP or RESTRICTING.
Here is what I would do and I would make it all one interlocking.
Personally I think the interchange track is very cumbersome and unweildly. It really isn't accessible to RR B (or even RR A) very convienently at all. If I had the room I would rearrange it like this. If I had room I would put in the optional light blue dotted connection. all the switches without a signal would be electric lock switches.
That about cracks it; plus I have much more understanding about what and why than if we'd just got straight tyo the "correct" answer. Thanks all
Then again... if someone wants to come up with another idea...
The 9one signal that I don't understand is RR A's Westbound 1st Main signal protecting the diamond. I was expecting this to be a single head the same as RR B's Westbound Main signal protecting the diamond.
I can see the "more logical" track arrangement of the second design. This would be easier to operate...but who, outside the real world, wants easy?
My figuring is that there are real etate constraints on what tracks there are. The dead end of the spur runs slap up against the concrete of a highway that goes over the west end of the layout. This makes the scenic break. It also has a "rational" history. In previous years there was only a tiny amount of interchange here. Eastbound switchimg moves from RR B could get to RR A's Eastbound track and shove cars back into the spur. An RR A switcher could then fish them out when the main was quiet. Once the bridge traffic coal was lined up to come over RR B this stopped being practical so then the new, direct connection got arranged and, eventually, built.
This means that the model gets a stretch of "absolutely, brand new and shiney RoW" for this short stretch to compare with track elsewhere. That raises questions about ties... If this is ultra new track there may still be bits of old roadbed waiting to be removed and stacks of scrap rail and ties waiting to be collected... raising more questions about where to put the stacks... shipping them straight away in MoW Gons is way too easy
Seeing as I have a small amount of ME concrete tied track I want to fit that in somewhere but I don't think it will be in the link line. It might be in the 1st Main with the 2nd Main having taken a very recent massive hit of heavy maintenance. This is my way of figuring in all the deatil that I'm always going on about, about MoW effects in track. (I realise that concrete ties were far less common in the US in the 1980s)
Thanks again everyone.
Any more ideas?
PS How about either of these for the RRA Main signals protecting the diamonds?
http://www.blmamodels.com/cgi-bin/webstore/shop.cgi?ud=BAkAAA8BBwIDBxQUEBEcHAQFBgUGAgwECQkTEQAA&t=main.blue.htm&storeid=1&cols=1&categories=01001-00011&&c=detail.blue.htm&t=main.blue.htm&itemid=4020
http://www.blmamodels.com/cgi-bin/webstore/shop.cgi?ud=BgAHAQ8BBwIDBxQUEBEcHA8MBgUGAgwECQkTEQAA&t=main.blue.htm&storeid=1&cols=1&categories=01001-00011&&c=detail.blue.htm&t=main.blue.htm&itemid=4030
Hmm? The first one looks a bit old in design to have been put in new in the mid 80s??? Would such a design be recycled from a different location?
Then again would the second one be too modern for mid 80s?
Dave-the-TrainThe 9one signal that I don't understand is RR A's Westbound 1st Main signal protecting the diamond. I was expecting this to be a single head the same as RR B's Westbound Main signal protecting the diamond.
My bad. That could be a single.
Dave-the-TrainMy figuring is that there are real etate constraints on what tracks there are. The dead end of the spur runs slap up against the concrete of a highway that goes over the west end of the layout. This makes the scenic break. It also has a "rational" history. In previous years there was only a tiny amount of interchange here. Eastbound switchimg moves from RR B could get to RR A's Eastbound track and shove cars back into the spur. An RR A switcher could then fish them out when the main was quiet. Once the bridge traffic coal was lined up to come over RR B this stopped being practical so then the new, direct connection got arranged and, eventually, built.
The stub track is only accessible to northbound trains on RR B. They would have closed the interchange rather than use that hokey connection. More likely it would be totally abandoned and the the interchange would be conducted at the yard. RR B would run a transfer into RR A's yard and vice versa. The "rational" explanation is that the interchange originally looked like my revised plan but when the overpass cut through the RR traded the track connection for something else. The transfer track would be one step above abandoned and extremely weedy. It would proably be used for storage.
What connection are you calling the "new, direct" connection?
Okay, got that signal on 1st Main
So if we take a few steps sideways onto 2nd Main (watching for trains of course) the "diverging route" east-to south bound signals the route to RRB that I.m talking about as the "new direct connection". Taking it that neither RR is dark to the other here (being on the same tower sited where Nick drew it in) it looks to me that this route will indicate red over green for a clear. Is that correct? Do I need a third, lower, head for the move into the switch lines... or?
Your "improved rationalisation for the stub track is superb! I really like that. Taking it a bit further...
The "improved rational" explanation is that the interchange originally looked like your revised plan but when the overpass cut through the RR traded the south end track connection for something else. The remaining stub of the transfer track would be used for storage rather than incur the expense of taking the east end out and removing it from the tower's interlocking.
It is possible that this would mean that there was no interchange facility as you suggest - at least for a time - or there may have been a very sharply curved connection that was okay for switchers and slow moving cuts of cars... but once the coal will be moving behind SDs there would be money to re-align the connection for smoother/faster running... not so much faster but the trains would be more free to keep rolling rather than having to slow right down to a crawl for a really tight curve through sharp switches,
The stub's track would have deteriorated to one step above abandoned and be extremely weedy... which fits in with the other thread where I was asking about urban and industrial trees. It is possible (probably more appropriate) that this stub will have lost it connection/been abandoned when the new connection for coal traffic was put in... This does very little to alter what's on the tower... maybe just the derail trhough to the bumper/wheelstops will remain poking out of weeds...
*******
How about either of these for the RRA Main signals protecting the diamonds?
Dave-the-Train Okay, got that signal on 1st Main So if we take a few steps sideways onto 2nd Main (watching for trains of course) the "diverging route" east-to south bound signals the route to RRB that I.m talking about as the "new direct connection". Taking it that neither RR is dark to the other here (being on the same tower sited where Nick drew it in) it looks to me that this route will indicate red over green for a clear. Is that correct?
So if we take a few steps sideways onto 2nd Main (watching for trains of course) the "diverging route" east-to south bound signals the route to RRB that I.m talking about as the "new direct connection". Taking it that neither RR is dark to the other here (being on the same tower sited where Nick drew it in) it looks to me that this route will indicate red over green for a clear. Is that correct?
Yes. Red over Green for a Slow-Clear through the diverging routes of the switches.
Do I need a third, lower, head for the move into the switch lines... or?
No. You can display a restricting signal with 2 heads. Bottom Yellow. (Red over Yellow on 2 heads, Red over Red over Yellow on 3 are both Restricting.) 3 head signals allow faster speeds through the switches. (Red over Green = Red over Red over Green = Slow Clear. Red over Green over Red = Medium-Clear)
Your "improved rationalisation for the stub track is superb! I really like that. Taking it a bit further... The "improved rational" explanation is that the interchange originally looked like your revised plan but when the overpass cut through the RR traded the south end track connection for something else. The remaining stub of the transfer track would be used for storage rather than incur the expense of taking the east end out and removing it from the tower's interlocking.
Except, as shown in Dave H.'s revised plan, the interchange track would probably connect directly to the switching lead and avoid the interlocking if at all possible.
How about either of these for the RRA Main signals protecting the diamonds? http://www.blmamodels.com/cgi-bin/webstore/shop.cgi?ud=BAkAAA8BBwIDBxQUEBEcHAQFBgUGAgwECQkTEQAA&t=main.blue.htm&storeid=1&cols=1&categories=01001-00011&&c=detail.blue.htm&t=main.blue.htm&itemid=4020 http://www.blmamodels.com/cgi-bin/webstore/shop.cgi?ud=BgAHAQ8BBwIDBxQUEBEcHA8MBgUGAgwECQkTEQAA&t=main.blue.htm&storeid=1&cols=1&categories=01001-00011&&c=detail.blue.htm&t=main.blue.htm&itemid=4030 Hmm? The first one looks a bit old in design to have been put in new in the mid 80s??? Would such a design be recycled from a different location? Then again would the second one be too modern for mid 80s?
Hmm? The first one looks a bit old in design to have been put in new in the mid 80s??? Would such a design be recycled from a different location? Then again would the second one be too modern for mid 80s?
Either of those would be perfectly appropriate to put in for the signals on the 2-main track portion of line A. Although the second design is far too modern for the 1980s. The first design is more akin to what would be around in that time frame. I might use the first bridge for parallel signals and BLMA also has 1 and 2 head mast signal available if you want to get all the parts from the same source. I don't know who makes a good dwarf signal though...
(Note that you _can_ use 2-head signals at all locations there, but the ones that have been identified as 1-head signals would have the bottom head as only ever Red. This is common on many RRs at interlockings..)
I think you're getting it now though..
cv_acrExcept, as shown in Dave H.'s revised plan, the interchange track would probably connect directly to the switching lead and avoid the interlocking if at all possible. Although the second design is far too modern for the 1980s. The first design is more akin to what would be around in that time frame. (Note that you _can_ use 2-head signals at all locations there, but the ones that have been identified as 1-head signals would have the bottom head as only ever Red. This is common on many RRs at interlockings..) I think you're getting it now though..
Although the second design is far too modern for the 1980s. The first design is more akin to what would be around in that time frame. (Note that you _can_ use 2-head signals at all locations there, but the ones that have been identified as 1-head signals would have the bottom head as only ever Red. This is common on many RRs at interlockings..)
Oops! Hadn't noticed that Dave H had put the connection into the switching road. I can see the logic of that.
Okay... back dating the layout... if there was enough traffic being interchanged for the track to connect into the Eastbound Main there would probably have been enough traffic for there to have been a connection with the Westbound Main as well. I think that in US practice this could have been done with a facing crossover between the East and West Mains placed to the east of the diamond. That might also be a time when the switching line was extremey busy.
We can then get a cut back which might leave the connection in the early pattern or shift it to the switching track.
Then when the highway ploughed through the east end the connecting line becomes a dead end spur but the geometry from under the bridge would be awful (because that suites the plot) so we can put in a horrible link to either the Eastbound Main or the switching track. The latter would involve a second diamond across the link between the Eastbound Main and the switching track. I don't see that as a problem...It could produce another interesting lump of ripped out track in the scenery when the track gets altered to the modelled phase.
I will try to sort out some sketches...
Of course a crossover between the Eb and Wb Mains would push the Westbound signals eastward and put a double head onto the Wb Main's signal... However! If I "rip that crossover out" with the new work I can end up with the mast still in place - waiting to be torched. I think that I;ve seen pics where the heads on a signal like that haven't been removed but have been swung 90 degrees to the right... Anyone confirm this please? Then I would get shiny new signals closer to the junction. Pity that second example is too modern,,, it's very pretty
Thanks again
Here you go Dave the latest sketches...
1940
1960
1965
1985
Thanks for all the brilliant help everyone.
Have a Great New Decade
I agree that it makes perfect sense on a model railroad to say "all signals are absolute" and thereby eliminate several multiple head signals, making wiring and operations easier. I think the problem we get into sometimes in these types of discussions is some folks are answering the question "how would a real railroad signal this track arrangement?" and some folks are answering the question "how should I signal this track arrangement on my model railroad?" The two answers aren't necessarily going to be the same, and the conflicting answers can cause some confusion in later posts.