CMStPnPOK now look at mark 28:05 on the video. He passes a flashing yellow with the train but then the one in the distance is now flashing yellow? So it made sense that once he passes a flashing yellow the next one is either solid yellow or red but this is so wierd and confusing.
One possibility is that he was riding on another train's yellows - a common enough occurance.
If that were the case, it's possibly that every signal would be flashing yellow, or perhaps solid yellow. If that leading train got further ahead (or got off the line - witness the yard that was passed), then you'd see all greens, which did seem to be the case.
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oltmannd Okay. You video shows what's going on. The signal in question was the home signal for the interlocking, but was acting as a block signal in this case. The flashing yellow is likely called "advance approach" and indicates the next signal will be at approach and the one after that, at stop (or stop and proceed). That's exactly what was happening. The route was cleared for the opposing train to take the siding. That meant the signal at the far end of the siding would be at stop and the signal at the near end would be at approach. Since there is not stopping distance (at least for a freight train) from the approach signal to the stop signal, you need the "advance approach" indication to get the train speed down to be able to stop. You can see the approach improve to a clear as the switch at the far end of the siding was set to normal and the signal cleared. This is an interesting signal system. No real intermediates, just interlocking signals and those short blocks at the center island stations. The meets occur at the stations - at least some of them.
Okay. You video shows what's going on. The signal in question was the home signal for the interlocking, but was acting as a block signal in this case.
The flashing yellow is likely called "advance approach" and indicates the next signal will be at approach and the one after that, at stop (or stop and proceed).
That's exactly what was happening. The route was cleared for the opposing train to take the siding. That meant the signal at the far end of the siding would be at stop and the signal at the near end would be at approach. Since there is not stopping distance (at least for a freight train) from the approach signal to the stop signal, you need the "advance approach" indication to get the train speed down to be able to stop.
You can see the approach improve to a clear as the switch at the far end of the siding was set to normal and the signal cleared.
This is an interesting signal system. No real intermediates, just interlocking signals and those short blocks at the center island stations. The meets occur at the stations - at least some of them.
OK now look at mark 28:05 on the video. He passes a flashing yellow with the train but then the one in the distance is now flashing yellow? So it made sense that once he passes a flashing yellow the next one is either solid yellow or red but this is so wierd and confusing.
dehusman What I can't figure out is why the leaving signals need two heads. All the indications I saw in the video could be displayed with one head (and would be on the UP or BNSF). A single head with a flashing yellow is an advance approach. Same thing, fewer heads.
What I can't figure out is why the leaving signals need two heads. All the indications I saw in the video could be displayed with one head (and would be on the UP or BNSF).
A single head with a flashing yellow is an advance approach. Same thing, fewer heads.
The leaving signals have a bottom head that can display two aspects. The next signal appears to be at a signal with a diverging route. I'd bet (but not the farm) that those leaving signals can display a yellow over yellow (approach diverging on UP) meaning be prepared to take the diverging route at the next signal.
Now on the BNSF, a flashing yellow is the same as a yellow over yellow. Proceed prepared to pass the next signal not exceeding 40mph and prepared to take the diverging route not exceeding prescribed speed through the turnout.
So one needs to know what the signal rules are for this particular line to really say why they do what they do.
Jeff
Dave H. Painted side goes up. My website : wnbranch.com
See these all the time on the BNSF "racetrack" in the Chicago area. As stated, it indicates there are two blocks to a stop signal. Next signal would be an APPROACH leading to a STOP. So we see a train leave a station and the nearby signal goes to RED as it is passed. As he clears the first block, it changes to steady YELLOW, As the train clears the second block, it changes to FLASHING YELLOW, and as he clears the third block, it goes to clear, GREEN. Speed limits in some systems like the former PRR Cab Signal had an Approach Medium indication of an diagonal head over a vertical head and allowed for 45 mph. Indicated that the engineer should expect an aproach (diagonal head) with a 30 mph speed restriction next.
For more on signals; see the rule book.
http://www.hubdiv.org/docs/signaling/NORAC.pdf
CTC is a method of operation. Anybody's signals can be used to implement CTC so long as the equipment behind the signals support the operation of CTC.
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CMStPnPWell actually it was double headed because it was double track ....... here is the video. Video mark 14:46.
At 14:46 the train is approaching the end of a siding, and the signal controls movement over the switch into single main track, not two main tracks or "double track". Don't quite understand why they need two heads on the leaving signals. Normally on the UP or BNSF, 2 heads are there to indicate diverging signals. Possibly they are planning to up the speeds on the routes and the signals are there for higher speed indications (e.g. approach clear 60).
By the way, to answer the original question, the "flashing yellow" means to reduce speed to 40 mph and be prepared to stop at the 2nd signal.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Rio Grande Valley, CFI,CFII
prk166Does TRE own their own tracks? Or are they just operating those commuter trains on someone elses? What the signaling means
It's the former Rock Island mainline between Dallas and Fort Worth. The line is nothing like the condition RI left it in though (see video above). The CTC tri-color signals are all new and LED. Searchlights and semi-phores long gone. I think they bought it for $60-70 million after the bankruptcy but not sure on the price. Most of the ties were sunk in the mud when they bought it some ballast here and there but not uniform, mixture of search lights and semiphores when they bought it but not CTC end to end like it is now............it had gaps. The video makes the track look really rough but it's really smooth something wrong with how the camera is mounted or the way the cab car is riding that makes the track look a lot rougher than it is.
The video starts at Texas and Pacific Station in downtown Fort Worth. The next station is Intermodal Station just North of the former Santa Fe Station which still stands but is vacant.
oltmanndIf this is a single headed signal
Well actually it was double headed because it was double track ....... here is the video. Video mark 14:46.
https://www.youtube.com/watch?v=qLnNKXn8_oo
prk166 Does TRE own their own tracks? Or are they just operating those commuter trains on someone elses?
TRE owns the tracks. It is owned jointly by Dallas Area Rapid Transit (DART) and the Fort Worth Transportation Authority (T). Each agency owns 50 percent of the line. Herzog Transit Services operates it.
BNSF and DGNO also run over a portion of the line. I have also seen a UP train on the line, but I believe it was being rerouted because of a problem on the UP line between Dallas and Fort Worth.
Does TRE own their own tracks? Or are they just operating those commuter trains on someone elses? What the signaling means
oltmanndYou would generally employ this kind of four aspect block signalling where block lengths are shorter than stopping distance.
Also used around here where there are "layback points". Let's say you have automatic signal 23W, then automatic signal 21W, then CP-Buck. But if you stopped at CP-Buck, you'd be blocking 4 highways. In the timetable, it may list 21W as the layback point (where you should stop your train instead of at CP-Buck). So if you get an advanced approach at 23W, you plan on stopping at 21W (which would display an approach). Otherwise you would have to be told by the dispatcher to hold back (and sometimes that doesn't always happen).
Your mileage may vary, refer to your rulebook or special instruction, if in doubt ask your managers. This is true for us;it may not be true for your railroad.
** posting is subject to a moderator delay, so if the answer is repeated, it's not the fault of either poster. (yeah, it's annoying).
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CMStPnP OK, I might have asked this before in the past or someone else might have. I just do not remember the answer. What does a flashing yellow light mean at a CTC signal. I noticed TRE is using flashing yellow now on it's tri-color CTC Signals between Dallas and Fort Worth. Also, is that universal signal across railroads or just specific to TRE (Trinity Railway Express).
OK, I might have asked this before in the past or someone else might have. I just do not remember the answer. What does a flashing yellow light mean at a CTC signal. I noticed TRE is using flashing yellow now on it's tri-color CTC Signals between Dallas and Fort Worth. Also, is that universal signal across railroads or just specific to TRE (Trinity Railway Express).
Signal aspects and indications are specific to the rule book for the particular railroad, although most use very similar schemes.
If this is a single headed signal not at an interlocking or the distant signal for an interlocking, it's an intermediate block signal, that is it just an indication of the presence of trains ahead on the track. Two and three headed signals would be at interlockings where the signals need to indicate the nature of the route e.g. is the switch normal or reversed.
A flashing yellow often indicates an "advance approach", meaning there's a train two blocks ahead so get ready for the next signal to be an "approach".
You would generally employ this kind of four aspect block signalling where block lengths are shorter than stopping distance.
TRE's particular practice could be differrent.
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