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.
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.
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is dependent on the timetable schedule but was done away with by the GCOR and in any case, any era, would have been superceded by the CTC.
Great, but what about ALL the tracks leading into the interlocking. What about them.
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…
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,
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.
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.
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).
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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 (1st 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 “Wh
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.
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
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. [banghead]
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 on
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
Oops! [:I] 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. [:D]
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
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.
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 br
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. [8D]
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.
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 prefer
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, I survived Christmas dinner at my in-laws. [8D]
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.)
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.
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
