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).
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).
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.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
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).
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.
Does TRE own their own tracks? Or are they just operating those commuter trains on someone elses? What the signaling means
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.
Rio Grande Valley, CFI,CFII
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
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.
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.
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.
Dave H. Painted side goes up. My website : wnbranch.com
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.
Never too old to have a happy childhood!
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
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.
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.
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
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.
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.
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.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
tree68 CMStPnP 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. 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.
CMStPnP 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.
'Riding the Yellows' has caused any number of rear end collisions over the years when the lead train stops with its rear end 'just' past a signal - following train passes his 'Yellow' signal expecting the next signal to also be 'Yellow", without being prepared to stop at the next signal and BLAM! The following train can't stop for the red. It makes no difference if signal system is CTC or just Automatic Block Signalling.
I found the video quite interesting. As has been noted by other posters, the line is mainly single track, with many passing sidings--and occasional wayside signals. I am somewhat puzzled by seeing the wayside signals as being absolute (no signal numbers).
This put me in mind of the first time I saw an advance approach aspect--on the IC's line above Haleyville, Alabama as I was on my way to Chicago on the IC's Seminole, 50 years ago. I asked the conductor as to what it meant, and he told me it was an advance approach signal--be prepared to stop at the second signal.
I do wonder where the zero mile post for this line is.
Johnny
CMStPnP 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). ... 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.
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). ...
...
The signal at 28:05 is red over flashing yellow. The red on top means you're going to take the diverging route.
To understand the flashing yellow on the bottom, re-read Jeff's post about flashing yellow (advance approach, be prepared to stop at the second following signal) vs yellow over yellow (approach the following signal prepared to take the diverging route). Note that BNSF, instead of having these two indications, just had the same indication for both aspects: "Approach Medium: Approach the next signal at 40 MPH or less." This can be used both to slow a train down for an upcoming yellow signal and to slow a train for an upcoming diverging route, so at some point they just got kind of smashed together. There's some loss of flexibility (because not all diverging routes are good for exactly 40 MPH, the signal will often be more restrictive than what the track will allow), but if you've got good sight lines to your signals trains can adjust up or down when that second signal actually comes into view.
With that said: my guess is that the red over flashing yellow aspect at 28:05 has a meaning somewhat akin to: "Proceed on diverging route, approaching the next signal at XX MPH or less." This can be used when the next signal is yellow (to ensure the train will be able to stop within that block), OR when the train has to be prepared to take ANOTHER diverging route at the next signal (28:53).
Dan
Deggestyhe line is mainly single track, with many passing sidings--and occasional wayside signals.
The video was edited quite a bit by the author, the line is a lot more double track than the video impression it leaves from the last time I rode. Also a number of rather long double track flyovers so as to skip numerous grade crossings in Irving and other places. On the single track portions there are a lot of passing sidings.
The T&P and Santa Fe stations in Fort Worth are also about 1.5 to 2 miles apart. The video editing makes them appear a lot closer together.
tree68One 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.
That could be it. The small yard is in Irving and you'll note briefly after it the line is triple track for a short distance. Irving is where the BNSF junctions with the line. I think it is the former FRISCO but I am not an expert on rail history in DFW. Just think it is former FRISCO because it is about where the FRISCO comes into Dallas.
I have seen Fort Worth and Western on the route and sometimes trains with BNSF units on them but no idea if it is pool power or not. The frieght trains are always fairly short on the line. I think FWWR has a BNSF switching contract as it junctions with this same line (from it's former Cotton Belt East-West mainline) about 3-4 miles North in Carrolton. Amtrak's Texas Eagle uses this TRE line as well.
CMStPnP Irving is where the BNSF junctions with the line. I think it is the former FRISCO........ Amtrak's Texas Eagle uses this TRE line as well.
The station is Downtown Irving/Heritage Crossing.
You are correct; the line coming down from the north that joins the TRE is the former Frisco line. There is a Y switch just north of the station so that trains coming off the Frisco line can go east or west. I have seen a couple of them headed east toward Dallas; I have never seen any headed to Fort Worth.
I have seen four or five Herzog balast cars, as well as other rail maintenance cars, parked opposite the station. My guess is that Herzog has been contracted to maintain the line as well as operate the trains.
jeffhergertThe 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.
That's probably it, I figured it was some additional aspect, probably for higher speed territory.
Way back when I was working on the D&H we had speed signalling cTc. and most interlockings were controlled by three-light signals. At certain junctions there were two diverging routes a train could take. At these locations the middle light would flash to indicate which diverging route was lined for your train. A note in the Employee's Timetable Special Instructions advised where these signal indictions were used and which route was controlled by the flashing middle light. Medium Clear and Medium Approach were the only indications where this flashing light was employed. The only other use of a flashing light was on a dwarf signal where a flashing yellow indicated Medium Approach rather than Restricting.
These special indications are unique to each railroad so there are many answers to your question.
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I can't imaging what it would be like if automobile traffic lights had the plethora of meanings that RR signals seem to have based on location. "A yellow light at a federal highway means you cannot enter the intersection, but at a state highway you are allowed to go though without stopping if the red light is blinking and you are a red car with a white top on Thursdays and Saturdays in the first two weeks of the month."
Sorry, I got carried away.
Semper Vaporo
Pkgs.
Semper VaporoI can't imaging what it would be like if automobile traffic lights had the plethora of meanings that RR signals seem to have based on location.
Those various meanings have caused a number of collisions, especially since all the mergers.
If one understands the various aspects, it should theoretically be possible to run a train virtually anywhere. A slow approach means essentially the same thing everywhere. Don't exceed the specified speed and be prepared to stop at the next signal.
"Right turn on red" was a California thing when I first got licensed. Now it's commonplace.
The new thing around here is flashing amber left turn arrows. Instead of having to wait for the next cycle to make your left turn when the "straight" lanes are green, you can make your turn if there's no oncoming traffic.
There aren't usually any signals, but traffic circles (rotaries, roundabouts) continue to confound people.
Other local customs like the "Michigan left" ("Jug Handle in NJ) can be equally confusing.
tree68 Semper Vaporo I can't imaging what it would be like if automobile traffic lights had the plethora of meanings that RR signals seem to have based on location. Those various meanings have caused a number of collisions, especially since all the mergers. If one understands the various aspects, it should theoretically be possible to run a train virtually anywhere. A slow approach means essentially the same thing everywhere. Don't exceed the specified speed and be prepared to stop at the next signal. "Right turn on red" was a California thing when I first got licensed. Now it's commonplace. The new thing around here is flashing amber left turn arrows. Instead of having to wait for the next cycle to make your left turn when the "straight" lanes are green, you can make your turn if there's no oncoming traffic. There aren't usually any signals, but traffic circles (rotaries, roundabouts) continue to confound people. Other local customs like the "Michigan left" ("Jug Handle in NJ) can be equally confusing.
Semper Vaporo I can't imaging what it would be like if automobile traffic lights had the plethora of meanings that RR signals seem to have based on location.
Locally there is a traffic light that governs traffic on MD 32 which passes under I-70 and governs the Left Turn that is required to get on the entrance ramp for I-70 East.
Light starts off with Green for SB 32 that is paired with a Flashing Red Left Turn arrow. After a period of time the Flashing Left Turn arrow extinguishes and becomes Solid Red Left Turn arrow - after a 3 to 4 second delay it becomes a Green Left Turn arrow. Can't count the number of times there have been vehicles nearly rear ended by those not paying attention when the lead driver stops for the Solid Red Left Turn arrow.
Man made signal problem that has no reason to be.
BaltACDMan made signal problem that has no reason to be.
Anyone else besides Maryland use the flashing red arrow? PennDOT in PA has been addign a lot of the yellwo falshing arrows this year. Also even adding solid red arrows, which until this year, have been rare in PA.
It is there out of expedience. We have some whoppers like it here. The idea is that you can prevent the 'go faster to beat the green arrow' problem by having the arrow go all the way to red (and be enforced by cameras or cops) for a moment even though it'll go to green again just a moment later.
Especially fun when highway bubbas install it at an intersection where long familiarity with the timing of green arrows and lights is established. Almost as evil as shortening the yellow when the red-light camera scam is implemented...
Semper VaporoI can't imaging what it would be like if automobile traffic lights had the plethora of meanings that RR signals seem to have based on location. "A yellow light at a federal highway means you cannot enter the intersection, but at a state highway you are allowed to go though without stopping if the red light is blinking and you are a red car with a white top on Thursdays and Saturdays in the first two weeks of the month." Sorry, I got carried away.
- PDN.
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