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"Signal tutorial ???"

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Southern_Railway (60 posts)
Jan-08-02, 10:35 AM (EST) "Signal tutorial ???" Is anyone aware of a signal tutorial? I have done a search of this forum and found various discussions, but nothing like a tutorial. Thanks,
Bill Alert Edit | Reply | Reply With Quote | Top
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Subject Author Message Date ID RE: Signal tutorial ??? blvdbill Jan-09-02 1 RE: Signal tutorial ??? bobs Jan-09-02 2 RE: Signal tutorial ??? LawrenceKellie Jan-09-02 3 RE: Signal tutorial ??? bobs Jan-09-02 4 RE: Signal tutorial ??? Southern_Railway Jan-09-02 5 RE: Signal tutorial ??? bobs Jan-10-02 6 RE: Signal tutorial ??? rgarber Jan-10-02 7 RE: Signal tutorial ??? bobs Jan-10-02 12 RE: Signal tutorial ??? Jitny Jan-10-02 8 RE: Signal tutorial ??? Southern_Railway Jan-10-02 9 RE: Signal tutorial ??? chuckzeiler Jan-10-02 10 RE: Signal tutorial ??? bobs Jan-10-02 11 RE: Yellow over yellow chuckzeiler Jan-11-02 13 RE: Yellow over yellow bobs Jan-11-02 14

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blvdbill (45 posts)
Jan-09-02, 01:17 AM (EST) 1. "RE: Signal tutorial ???" Hey Bill, Checkout this guy webpage http://home.cinci.rr.com/botzland/ ..... he has a short signal tutorial on there.Bill Remove | Alert Edit | Reply | Reply With Quote | Top
bobs (335 posts)
Jan-09-02, 02:58 PM (EST) 2. "RE: Signal tutorial ???" Are you looking for information on what types should be placed where or info on how to write scripts and design them in MSTS? Remove | Alert Edit | Reply | Reply With Quote | Top
LawrenceKellie (1049 posts)
Jan-09-02, 03:13 PM (EST) 3. "RE: Signal tutorial ???" *I* would be interested in what types where.Lawrence Remove | Alert Edit | Reply | Reply With Quote | Top
bobs (335 posts)
Jan-09-02, 06:01 PM (EST) 4. "RE: Signal tutorial ???" I've been thinking of writing one. By its nature though, any tutorial can only apply to what one railroad or area does, and there are lots of variations, some today and even more historically. Remove | Alert Edit | Reply | Reply With Quote | Top
Southern_Railway (60 posts)
Jan-09-02, 07:57 PM (EST) 5. "RE: Signal tutorial ???" I was looking for information on where to place them, when and how to link them, etc. Remove | Alert Edit | Reply | Reply With Quote | Top
bobs (335 posts)
Jan-10-02, 02:16 AM (EST) 6. "RE: Signal tutorial ???" OK.The short, simple example is one track with a switch. As you approach the switch from the points end, an absolute signal with two heads would tell you which path you would take. The top head is linked to the straight path, the bottom head to the diverging path. What particular aspects this signal shows would depend on how the switch is thrown and the condition of the blocks ahead on the selected path. Prior to this signal, the train would have passed another signal that was permissive and provided warning of the state of the switch ahead, as well as the condition of the path past that switch. Again, there would be two heads linked to the same pieces of track as the absolute signal. If enough distance was involved, there would be one or more permissive signals prior to this one too. These would allow more than one train into the area, but would keep them spaced safely apart.Coming from the opposite direction both legs would have an absolute signal at the switch that would either allow a train to proceed, or not depending on the state of the switch and whether or not the path ahead is clear.That's the short answer. The long answer includes a bunch of exceptions and conditions caused by varying track structure.To learn more, I'd recommend the Railway Technical Pages papers on signaling at <http://www.trainweb.org/railwaytechnical/index.html>
plus looking at the signaling on existing routes such as what we just did on Marias 3. Be aware that there are two predominent schemes in the US and Canada, those based on the NORAC rules and those based on GCOR.
Other countries use different rules, lighting schemes, etc., some similar, some very different than the two I described. Some of the papers on the RTP show different country implementations. Remove | Alert Edit | Reply | Reply With Quote | Top
rgarber (1013 posts)
Jan-10-02, 08:46 AM (EST) 7. "RE: Signal tutorial ???" LAST EDITED ON Jan-10-02 AT 08:48 AM (EST)Bob,Okay, I got one for you... Interval signals make sense, but grade signals? Why did they bother? Why not just let the train get to the top of then hill and then give it a signal. Why put one in the middle of a grade?Rich Garberokay.. let me qualify that.. I mean a grade that's steep enough it's better to let the train slowly creep past a signal so it doesn't have to stop.. is what I mean. Remove | Alert Edit | Reply | Reply With Quote | Top
bobs (335 posts)
Jan-10-02, 08:15 PM (EST) 12. "RE: Signal tutorial ???" LAST EDITED ON Jan-10-02 AT 08:19 PM (EST)Rich, you would ask one of the questions that I'm not sure about! Notice I didn't use any grade signals on MP3.My understanding is that these are only found where a permissive signal would be. In fact, a number plate defines a permissive signal, and grade markers are always found with number plates. If a non-grade permissive signal has a red, it means stop and proceed at restricted speed. The grade marker says, essentially, you don't have to stop, but you do have to proceed at restricted speed. As I've heard it, this would be used in a place where, if the train stopped, it might not get going again, so it liberalizes the stop and proceed rule. I'm also told that it is used on the down side of the grades sometimes, where stopping a train without going into emergency might be very difficult.In MSTS it doesn't matter because a permissive red, even though it means you have to stop, doesn't force you to stop. While the sim will end if you pass an absolute signal, it won't if you pass a permissive.Why not just wait for the top of the hill to put the signal? Remember the purpose of permissive signals is to allow trains to follow each other through blocks closer together. If you only put the signal at the top of the hill, or probably over the top where the train would be balanced over the peak, it would make for a much longer block, thereby spacing out the trains more than necessary. Remove | Alert Edit | Reply | Reply With Quote | Top
Jitny (102 posts)
Jan-10-02, 09:25 AM (EST) 8. "RE: Signal tutorial ???" BobsVery good infoRegards
Bob
Mobile AL
M&O,GM&O,CSX,IC,SOUTHERN,BNSF,L&N

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Southern_Railway (60 posts)
Jan-10-02, 09:49 AM (EST) 9. "RE: Signal tutorial ???" Bobs,Excellent information. Thanks for your help. Remove | Alert Edit | Reply | Reply With Quote | Top
chuckzeiler (158 posts)
Jan-10-02, 10:46 AM (EST) 10. "RE: Signal tutorial ???" I have a question about the signal practice on the Marias pass V3.0. I've encountered several yellow over yellow signal displays, all of them seem to be distant signals. For instance, eastbound, coming down from Summit, diverting left into Bison siding, the distant signal at MP1147.5 (lat 48.35284, lon -113.30406) shows yellow over yellow. This doesn't tell me that I'm diverting, only that both tracks are "approach, prepare to stop at the next signal". I would expect to see red over yellow if I'm diverting. Is yellow over yellow a correct signal display? I've also encountered a yellow over lunar distant signal display at MP1140.5 (lat 48.41940, lon -113.22984) diverting into Glacier Park siding. I dug out my copy of the Burlington Lines rule book, and the lunar display tells me I should hand throw the next switch, but once again, I would expect the top signal to be red, indicating I should take the siding. Remove | Alert Edit | Reply | Reply With Quote | Top
bobs (335 posts)
Jan-10-02, 08:08 PM (EST) 11. "RE: Signal tutorial ???" This is where different lines do different things. I based what the MP signals do on the then current BNSF signals document. In the Marias3 zip file root is a document called Signal Aspects and Indications for MP30.doc. That is my version of the BNSF document, leaving out a lot of aspects that I didn't use but that could be valid.If you read this carefully, or read the original BNSF doc, you'll see several possibilities for an Approach Medium. In my doc, I split these onto two lines with the double yellow indicating an upcoming diverging signal. In the BNSF doc, they don't distinguish between the double yellow and a single flashing yellow. Both mean be "prepared to pass next signal not exceeding 40 MPH and be prepared to enter diverging route at prescribed speed." Prescribed speed would be the speed allowed for the turnout which may or may not be less than 40. BTW, BNSF has just revised this rule to say 30 MPH instead of 40. So, I distinguished between an Approach Medium for a straight path (flashing yellow or FY over Red) from an Approach Medium for a diverging path (double yellow). Remember, I wrote these scripts to be prototypical on the BNSF, not CSX or some other line.The yellow over lunar is Approach Restricting and means the next signal will show a restricting indication. It doesn't indicate whether or not there is a divergence, but since the intent is to get the train down to restricted speed anyway, the next signal can show the divergence, which would be Red over lunar.In doing all this, I had to throw out one thing I had always thought was correct. In a straight path, proceding from most restricting to least, I would expect to see red (stop), yellow (approach), flashing yellow (approach medium), green (clear). If I was coming up on a divergence that would show red over yellow (diverging aproach), then I would have expected the prior signal to show red over flashing yellow, the same sequence as for a straight shot. But that isn't the case. Red over flashing yellow can't be seen on a permissive signal, according to the BNSF rules. That's where the double yellow comes in.
Red over flashing yellow is only seen at a switch, indicating a divergence, and saying that you need to be slowed down to 35 MPH by the next signal. Clear as mud?? Remove | Alert Edit | Reply | Reply With Quote | Top
chuckzeiler (158 posts)
Jan-11-02, 10:11 AM (EST) 13. "RE: Yellow over yellow" Yes, actually, it is clear, although I had to read it a couple of times. And you're right, it's all there in the documentation that came with the route, I should have looked at that first. Sorry to have wasted your time, and thanks for the explanation, and the route improvements. Guess I better bone up on the BNSF Operating Department rules. Remove | Alert Edit | Reply | Reply With Quote | Top
bobs (335 posts)
Jan-11-02, 09:23 PM (EST) 14. "RE: Yellow over yellow" Chuck, it wasn't a waste of time. I had to double check myself a lot while developing that because it didn't seem right to me either. I'd misread or misinterpreted the BNSF signal chart a lot and kept wondering why things didn't look right! Remove | Alert Edit | Reply | Reply With Quote | Top

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