I am developing various signaling systems for modelrailroad in my hobby. Last month, UP(UnionPacific)RR signaling system to be simplified for modlrailroad has been completed. How to assemble them is shown on my web site linked below. Every info for the hardware and also download software are shown. If you have a PIC -writer like Microchip’s PicKit, you may be able to assemble by yourself.
If you have any comments or suggestion for the signaling system, please tell me. Then, I am going to CROR (Canada) signaling system.
----- Question is from here.
CROR is based on speed signaling , where diverging speed limit is explicitly shown as signal aspects. In any railroads, most turnouts will consist of a straight diverging route and a curved diverging route. In that case, when the straight route is set on the turnout, the signal just before the turnout will show Clear (G/R or G/R/R). Then, when the curved div. route is set there, the signal will show any diverging signal aspect corresponding to the speed limit. This is normal signal operation.
Both photos show simple siding exit situations in CTC. One photo shows a two headed absolute signal for the siding. The exit signal does not show in the other photograph.
In North American practice a “wye” is a track arrangement by which a diverging route, think branch line, can be accessed from the main line in both directions, or which is used to turn equipment, typically locomotives. Geometrically a wye is just a triangle with tails on all three ends. Calling the track arrangement in the photos a y is both confusing and incorrect.
In GCOR, western US practice, the siding exit switch is either 3 or 4 aspect. Four aspect would be Red, Yellow, Flashing Yellow, and Green. The train may exit the siding on anything better than Red. I am 99% confident the Canadians are very similar.
The two headed signal may be used in the way that two headed block signals were once used in the US, that is to give condition of the NEXT block ahead. If so the aspects conveying the same information as above would be Red over Red, Yellow over Red, Yellow over Yellow, and Green over either Yellow or dark. I am soft on this so you would need both the rule book and the CP’s signal rules/chart to know what they are doing.
Also note that since this is CTC territory these are “Absolute” signals. Absolute signals are designated by lack of number plates or by a letter “A” on the signal mast. An absolute signal aspect better than “Stop” conveys authority to proceed to the next absolute signal. In most cases there will be a number of intermediate block signals between absolute signals.
The only useful comment I can add here is that an “equilateral turnout” - one where the angle and curve is symmetrical in each direction, instead of the more usual 1 straight route and 1 curved route - is indeed also informally known as a “Y” or perhaps “wye” turnout, for an obvious reason, I think. That can indeed be confused with the 3-pointed ‘turnaround’
I do not think the turnout in the second photo is an equalateral. It is the east switch at Field BC and is at the bottom of the drop off the Continental Divide at Kicking Horse Pass. The train is still on the 2.2% grade off the pass, while the power is on substantially less downgrade. I believe there is a short horizontal curve just beyond the power as the power is clearly on a different heading than the front portion of the train.
The curve into the siding switch looks typical of a straight sided switch. More important, an equalateral swith would be wasted here as track speed is in the 20-25 MPH range. The whole point of an equalateral switch is to allow relatively higher speed movement over the diverging side than would otherwise be allowed holding frog number constant. In extreme cases this may result in a lower speed on what would have been the straight side. There is no reason for an equalateral switch at this low speed location.
Yes, it could be that from the camera’s angle, the vertical curve from the downgrade into the flatter siding fools the eye into thinking that it is a horizontal curve - right about at the rear of the loco consist. Or, it may be actually be a horizontal curve, though I don’t immediately see what purpose one would serve there, either - why not just continue straight into the foreground track ? And in front of the lead loco, at the left edge of the image, the rails seem to curve towards the camera, as they would with a ‘return to tangent’ curve at the entrance to a siding from a curved side of a turnout - or that may be simply a result of distortion at the edges of the camera’s telephoto lens. Either way, it’s not conclusive to me from this image. I also tried looking at a couple of the aerial photos and some other sources, but no luck there either on a definitive view.
I agree with your second paragraph about an equilateral turnout not serving any great purpose here - unless it might be to allow a faster ‘leaving speed’ from both tracks for trains ‘taking a run’ at the grade of more than the 20 - 25 MPH that you mention ?
I am 99.9% sure the train on the photo is taking the main track side of the turnout. In terms of leaving speed if there is no meet an eastbound will be on the main and subject to whatever speed restriction applies on the main plus any limit associated with the curve we see in the distance. I would expect the 20 or 25 MPH restriction to start at the switch or at the first curve we see in the distance. The reason for this is that the curves will probably be superelevated to balance at about 15 MPH. Descending trains at 20 will be a bit over balance speed, and ascending will be at 10-15 MPH probably a bit underbalanced. The under balanced trains will have more than half of their weight on the low rail which will tend to depress that rail over time increasing superelevation. At some point that increased superelevation will increase the risk of stringlining a train.
You are probably aware that railroads have tended to flatten superelevation of curves on mountain grades, even if it drops the speed, because of balance issues. I know that Stevens Pass in Washington State was posted for 25 MPH as of late 1960’s and is now posted for 20 MPH. I am certain they have flattened the superelevation in the curves. In the long ago past, 1910-1920, I understand the line was posted for 30 MPH, this at a time steam powered freights made 5 or 6 MPH up the hill. I suspect only passenger trains moved 30 MPH downgrade even then.
In terms of leaving speed eastward from Fields siding, I suspect very few trains could get to 25 MPH from a standing start given the hill facing them. I come to the same conclusion, this is not the place for an equalateral turnout.
Thanks for immediate replies. “y-shape” was wrong to describe the symmetric turnout. In addition, the turnout observed in those photos in Field, British Columbia, seemed to be symmetrical in my eye but my eye may be incorrect.
What I asked is that how CROR’s speed signal is operated, if there is exactly symmetrical turnout. For the both curved diverging routes, is any diverging signal aspect, such as “Slow to Clear” in CROR rule, shown for trains arriving at the station ? Otherwise, for one of those two diverging routes, “Clear” (G/R) is shown ? Or, such exactly symmetrical turnouts do not exit in North-America ?
If the general speed limit for the track in question is no more than the allowable speed through the turnout, there is no reason why the signal should show a restrictive indication. My memory is now slightly hazy but I believe when CP’s West Toronto Jct was rearranged ca 1980, there is an intersting example. Track No.1 of the Galt Sub used the diverging leg of a No.13 turnout, and since the speed limit for that track was 30mph it could get a clear signal. (CPR considered the No.13 turnout good for 30mph then; the permissible speed has since been reduced.) Straight through was a connection to the Mactier Sub, and I believe would show a more restrictive indication, although that may also have been related to four tracks it crossed on diamonds and the turnout at the far end where it joined the Mactier Sub.
As to the turnout at Field, the general arrangement is that of an equilateral turnout, although I can’t say what size, or whether it may be a fudged equilateral. It is not required for speed since most freights are only doing 10-15mph (ignoring the rare occasions of brake problems!). Both tracks are used fairly equally, so the easing of the geometry will reduce the wear on track components. Assuming it is a No.13, in essence you get the equivalent of a No.26 turnout, without the cost of the bigger components. In winter it will be a lot easier to keep 22’ switch points operating than 39’ ones.
I have added two photos showing trains at the turnout in question, one using each side. There has been some discussion about whether the original picture was deceptive, but you can clearly see that there is no straight side. The optics can be misleading. I have no direct knowledge of what signal aspects can be displayed at this site.
Track No.1 of the Galt Sub used the diverging leg of a No.13 turnout, and since the speed limit for that track was 30mph it could get a clear signal., Straight through was a connection to the Mactier Sub, and I believe would show a more restrictive indication
As you say, curved diverging route may show “Clear” when the diverging speed limit is not needed to be warned. Your real example is intresting. I can understand that. While, as for the straight route at the turnout, any curved divergiing route may be continued after that. If so, I can easily understand the more restricting indication, too.
Field’s track configuration is very simple. There is just a turnout. If any diverging signal aspect is not shown when a train comes down there, the lower head of two heads signals will be dummy head. It may be possible in absolute signal. However, as other peoples pointed out, the turnout may not be exactly symmetric. The right-side track, i.e. the dwarf signal’s side seems to have a loose diverging curve. Very confusing.
Not quite. At Field there is the complication that they are approaching a yard, and it is a different RTC controlling the exit at the far end. If the main track is fully circuited to the other end of the yard, which I think is probable, a train taking that route will get at least a clear to stop (yellow over red) signal if the line is clear. A clear signal is also a possibility if the signal system on the next subdivision is linked, and this is likely the case. Of course since the crew changes at the station the train is “delayed in the block” so the clear signal is almost pointless.
On the siding track, I think a train will be entering “dark territory” since typically yard tracks do not get circuits. So in this case the signal will be a restricting signal, red over yellow, so the lower head is also functional. It is quite possible there is a short section of the siding that is in fact circuited, perhaps as far as the start of the yard, round the bend behind the photographer.
Sometimes the circuits are set up so a restricting signal can also be given for the main track when there is a train or cars already occupying the block. This is usually only included where there are specific reasons to want it, and is sometimes called a “return to train” feature. No idea whether Field has it or not.
a train will be entering “dark territory” since typically yard tracks do not get circuits. So in this case >the signal will be a restricting signal, red over yellow, so the lower head is also functional.
I have never been in Field. Sattelite map in internet was also not available in the area, due to very low resolution (I don’t know why). So, your comment is helpful.
By the way, the restricting signal R/Y can be shown in my developing CROR signaling system for modelrailroad. Like UPRR version which has been already completed, when CROR version was completed, I will update youtube movies of some signal operations may be observed in such complicated track configurations.
For Y-shape turnout, it can be located in my CROR signaling system but I may not comment about it.[%-)]