Advance Appraoch on the BNSF

I'm trying to figure out this indication. What are the possibilities for the next signal after it? Advance Approach is defined by the BNSF as "proceed prepared to pass next signal not exceeding 50 mph and to advance on diverging route", and the aspects are Y/G or Y/G/R. There are a lot of 50 mph crossovers out here in New Mexico on the Clovis and Gallup subdivisions, and I assume they use the Advance Appraoch indication before a Diverging Clear (R/G) on a 50 mph turnout, but would would a train see Advance Approach before a Diverging Approach Medium (R/Flashing Y) "Proceed on diverging route not exceeding prescribed speed through turnout prepared to pass next signal not exceeding 35 mph"? Or would it see Approach Medium (Double Yellow, or Flashing Yellow, etc.) "Proceed prepared to pass next signal not exceeding 40 mph and be prepared to enter diverging route at prescribed speed" instead of the Advance Approach?Also, confusing things, is that there is a special rule in the timetables for those two subdivisions, that the aspect R over Flashing Y means Diverging Approach, not Diverging Approach Medium, so in effect, there is no such indication as Diverging Approach Medium on these subdivisions, which leads me to believe that prior to a Red over Flashing Yellow aspect at a 50 mph turnout, a train would see Appraoch Medium and not Advance Approach, reserving the Advance Approach indication only when the next signal is Diverging Clear at a 50 mph turnout.Any and all help on the matter would be greatly appreciated. I'm especially interested in why there would be this special rule effectively eliminating the Diverging Appraoch Medium indication.Thanks!Mark

Moffat Road Tabernash to Phippsburg
All track complete
Currently working on tunnels and bridges

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RE: Advance Appraoch on the BNSF, Mountain Biker, Apr-08-04, 09:52 AM, (1) RE: Advance Appraoch on the BNSF, chazlee1, Apr-08-04, 01:06 PM, (2) RE: Advance Appraoch on the BNSF, markhyams, Apr-08-04, 09:59 PM, (3) RE: Advance Appraoch on the BNSF, Mountain Biker, Apr-08-04, 11:46 PM, (4) RE: Advance Appraoch on the BNSF, BN_9402, Apr-09-04, 01:07 AM, (5) RE: Advance Appraoch on the BNSF, markhyams, Apr-09-04, 01:36 AM, (6) RE: Advance Appraoch on the BNSF, BN_9402, Apr-14-04, 07:28 PM, (8) RE: Advance Appraoch on the BNSF, markhyams, Apr-14-04, 05:16 AM, (7)

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Hi Mark,Although I cannot speak for the entire BNSF, out here on the Stockton Subdivision the only places that we might get an Advance Approach is when we are on single track CTC preparing to diverge onto 2MT CTC.In fact on the Stockton Sub the fastest turnout we have entering and leaving CTC 2MT is 50 mph. In my limited experience, I have never actually seen an Advance Approach signal ahead of a Diverging Clear at this location. However I have seen a Approach Limited (Prepare to pass next signal not exceeding 60mph and to advance on diverging route at perscribed speed) entering this location. Why we get this signal in lieu of Advance Approach is beyond me. I have been told that, "...its just the way that the system is wired..."As far as the Diverging Approach and Diverging Approach Medium thing goes, this is what I've been told.The old Santa Fe had their CTC system wired with intermediate signals in the majority of their longer sidings. This meant that when the DS put you in the hole you would get "Eggs for Breakfast" (a Double Yellow) or a Flashing Yellow at the approach signal, D-A-M signal at the turnout, an Approach at the intermediate in the hole...followed by all red at the opposite end of the siding. At certain locations after the merger intermediate signals began to be phased out, but to keep from having to rewire the system they found it easier (and cheaper) to ammend the subdivision special instructions to effectively eliminate the Diverging Approach Medium signal indication.......confused?BTW we do have that ammendment to the special instructions on the Stockton Sub as well.I hope that this helps...I probably could have explained it better if it wasn't soooooo early in the AM Regards,
Tom Doyle

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Here on the Nebraska Division, we can get an AdvanceApproach indication (yell/grn, yell,grn,red) in advance of a 50 MPH turnout when going from single main to double main tracks and also in advance of a 45 MPH CROSSOVER (main one to main two, for example). In either instance the aspect after this signal can be a Diverging Approach(red/yellow); Diverging Approach Medium (red/flashing yellow); or Diverging Clear (red/green). Either way, it always precedes a diverging signal. Hope this helps.

Happy Rails,
Chaz
(BNSF Conductor)
<>

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Thanks for the answers guys! I really appreciate it. Of course now I have another question.Here's the situation:
Main 1 on the right, Main 2 on the left, siding off of Main 2 in the distance, dual 50 mph crossovers, and a 40 mph turnout to the siding (this is at the western end of the Clovis Sub in NM, just west of Abo Canyon, if you're curious)My question is this: Are the signal circuits smart enough to know whether the train is approaching a 50 mph or 40 mph turnout within the same interlocking, thereby giving the advance approach indication if only a crossover is open, but giving the Approach Medium indication if the siding switch is open, even if a crossover is open too? My guess is yes, but I wasn't expecting to hear that an Advance Approach can preceed a Divering Approach, so I don't want to guess anymore!I'm working on some signal scripts that I hope to incorporate into a MSTS version BNSF Gallup Sub (my new home railroad, since moving to Albuquerque a few months ago), which is next on the agenda, after finishing up with my Moffat Sub. We'll see how soon that is! I asked a question in the route-building forum (http://www.train-sim.com/dcforum/DCForumID6/11716.html) on how to script this same interlocking, and I made some assumptions there that I now think may not be true, which is why I'm trying to get them cleared up here. Thanks again everyone for all your help!Cheers,
Mark

Moffat Road Tabernash to Phippsburg
All track complete
Currently working on tunnels and bridges

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>My question is this: Are the signal circuits smart enough
>to know whether the train is approaching a 50 mph or 40 mph
>turnout within the same interlocking, thereby giving the
>advance approach indication if only a crossover is
>open, but giving the Approach Medium indication if the
>siding switch is open, even if a crossover is open too? My
>guess is yes, but I wasn't expecting to hear that an Advance
>Approach can preceed a Divering Approach, so I don't want to
>guess anymore! Well I'm really not a signal person so I'm probably not qualified to answer this question.However this is CTC, otherwise known as "the mother may I railroad", and in your picture I am assuming that I am looking at the westbound control signal for Beevers, which is a control point.My guess would be that the signal at this location is only going to be as smart as the DS in the situation that you have presented. In other words if the DS was going to line you into the siding off of main 2 (assuming that main 2 is a controlled siding) then you would get an approach medium only if the siding off of main 2 was a control point as well (and was governed by its own signal). In which case the logical signal progression would dictate a diverging approach signal at the entrance to the siding.Because we are looking at 2MT CTC, it is possible that the siding off of main 2 could NOT be a controlled siding, in which case you would get a RESTRICTING (flashing red over red) signal at the control point shown in your picture.The signal aspect will be a result of the way that the dispatcher has lined the train, not how "smart" the signal circuits are. Once the DS has lined the trains intended route, the only thing that will affect the signal aspect is something like a broken rail or a switch opened manually (which would be a major no-no if it were done without permission from the DS)or the presence of another train approaching from the opposite direction.In my humble opinion, I would say that your guess is correct.Regards,
Tom Doyle

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Not to interrupt the conversation or anything but heres the CP at Beevers as it is in Train Dispatcher 3. I presume the actual DS screen in Ft. Worth looks somewhat similar to it.Austin

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Very cool! Thanks for sharing that, and no, you are not interrupting. This matches what I saw on location and on the timetables, which show Beevers as a controlled siding.Mark

Moffat Road Tabernash to Phippsburg
All track complete
Currently working on tunnels and bridges

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Just for whats its worth, I noticed you were talking about designing the Gallup Sub after the Moffat route is done. Here's the Gallup in TD3.Austin

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I think I got this figured out. The consensus seems to be that, yes, if you're going through a crossover, you'd see Advance Aproach (Y/G) at the signal prior to the interlocking, and if you're going to the siding, you'd see Approach Medium (Y/Y or flashing Y) at the signal prior to the interlocking. Thanks for your help, everyone. Including those whom I talked to away from this forum.Cheers,
Mark

Moffat Road Tabernash to Phippsburg
All track complete
Currently working on tunnels and bridges

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