ns145Never been a fan of using a red-over-yellow signal for a restricting indication. I live on a former N&W line, so red-over-yellow is a Restricting but red-over-yellow-over-red is a Diverging Approach. That is not the case for NS' former Southern territory. This subtle inconsistency is dangerous in my opinion, especially if crews operate over routes with multiple sets of signal rules. Lunar would be a much better standard color to use across the industry for restricting aspects. I know - not going to happen, it would cost too much to standardize. Safety first! Right... About 15 years ago the local NS dispatcher caught a UP crew operating on joint NS/UP trackage miscalling a yellow-over-yellow-over red signal an Approach Diverging rather than an Advance Approach. Could have caused an accident because an Approach Diverging tells a train to slow down and prepare to proceed thru a diverging route. An Advance Approach means stop at the second signal. In this particular instance, due to short signal blocks, the second signal was only 5,800 feet away. I was impressed by the DS' keen ear and instant understanding of the ramifications. Of course, he was an "old head" with 30+ years on the railroad. I have no doubt that he had studied all of the signalling charts on the districts that he dispatched and knew all of the signal aspects, names, and indications that each signal on his territory was designed to display. By signalling charts, I mean diagrams of the inter-relationships of signal aspects between signal locations along each route, not the basic signal rule charts.
About 15 years ago the local NS dispatcher caught a UP crew operating on joint NS/UP trackage miscalling a yellow-over-yellow-over red signal an Approach Diverging rather than an Advance Approach. Could have caused an accident because an Approach Diverging tells a train to slow down and prepare to proceed thru a diverging route. An Advance Approach means stop at the second signal. In this particular instance, due to short signal blocks, the second signal was only 5,800 feet away. I was impressed by the DS' keen ear and instant understanding of the ramifications. Of course, he was an "old head" with 30+ years on the railroad. I have no doubt that he had studied all of the signalling charts on the districts that he dispatched and knew all of the signal aspects, names, and indications that each signal on his territory was designed to display. By signalling charts, I mean diagrams of the inter-relationships of signal aspects between signal locations along each route, not the basic signal rule charts.
Not all carriers have rules in place requiring crews to call out on the Road Radio Channel the signal indications and location of what they are seeing.
Additionally, Dispatchers are not required to be monitoring the Road Radio Channel - they do so, if and when they want to.
Never too old to have a happy childhood!
Never been a fan of using a red-over-yellow signal for a restricting indication. I live on a former N&W line, so red-over-yellow is a Restricting but red-over-yellow-over-red is a Diverging Approach. That is not the case for NS' former Southern territory. This subtle inconsistency is dangerous in my opinion, especially if crews operate over routes with multiple sets of signal rules. Lunar would be a much better standard color to use across the industry for restricting aspects. I know - not going to happen, it would cost too much to standardize. Safety first! Right...
Some signals are speed, some are routing. Even the speed signals can give an indication regarding routing if you're familiar with the track layout.
At risk of repeating myself (I didn't go back to look at what's been written previously), standard signals assume three heads. Top head is track speed (whatever it happens to be). Middle head is medium speed, bottom head is slow speed. If there are less than three heads, assume them to be missing from the bottom up, and assume them to be showing a stop.
So, a "high green" is a signal to proceed at track speed. A middle green indicates that a train must reduce to medium speed (defined in the timetable), and a bottom green means proceed at slow speed. As mentioned, it varies by railroad, but it's kind of a rule of thumb. Yellow in any of those positions indicates that the next signal may be red (stop) and to proceed accordingly.
There are myriad variations - flashing, multiple heads in different colors, etc. It's best to find a signal chart for the railroad in question and look up the governing rule for each signal indication.
B&O CPLs are a world unto themselves, but actually really easy to understand once you get the hang of them.
As mentioned, signal indications can vary by railroad. This was the root cause of a rear-end collision involving Amtrak in the Chicago area several years ago. The engineer didn't account for having changed host railroad and mis-interpreted a signal indication. Same indication, different meaning on a different railroad.
Some signals may have a head with a permanent red/stop in one or more positions. The signal on the SW transfer/wye leading out to the main at Deshler has only one indication on the top head - red. The middle head has two, one of which I believe may be lunar, for a restricting aspect. The bottom head has all three lamps. You can sometimes see that signal on the Deshler PTZ.
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...
While "All About Signals" is rather dated (the TRAINS articles were from 1955). it is still useful for giving the basics of both over the road operation and interlockings.
Larry (tree) has a great suggestion regarding the Deshler web cam. It shows those great B&O CPL signals in use on the PTZ camera. What great relics those are.
I have always been intrigued and studied signals. About 50 years ago I purchased a Kalmbach book "All About Signals" which was a reprint of a couple of Trains articles. Still have it..somewhere.
ed
If you want to understand US railroad signaling, study this:
Al Krug's Signals Page (archive)
There is a logic to the system, and it's used in different ways by different railroads, but it boils down to the same stuff. It's only confusing until the "ah-ha!" moment where you get it.
I came across this video from the FRA while looking for something else. A North American signalling 101 if you will.
https://www.youtube.com/watch?v=ZztUxEUi290
Jeff
It may be of interest here to mention the bible of British railway signalling, a book by L T C Rolt called "Red for Danger." This is still readily available on the secondhand book market.
The author explains how and why signalling developed in Britain: why we do what we do and what is likely to happen if you don't do it.
Although North American signalling practice is different to British the fundamental problems are the same and anyone wishing to explore the theory of signalling would find it a most rewarding read.
tree68 Lithonia Operator I've now come to the conclusion that all I need to do is: Get hired by a railroad in T&E service, and memorize the rulebook. Then I need to work there for a year or so, to learn how things work in the real world. And, you have to learn exactly what a given signal indication means in each specific location... This is one reason crews need to be qualified on their territory. Granted, the vast majority of signal indications mean the same thing all over a given railroad (historical considerations notwithstanding), but there can be exceptions. Once you get the basics down, having a signal chart that applies to the railroad where you're watching will generally get you where you need to be. I have the chart for the B&O CPLs on "speed dial" on my computer as I watch Deshler on-line. F'rinstance, sometimes the dispatcher will line another train up immediately behind one that has just passed. Viewers can then watch one of the signals go from "restricting" to "approach" to "clear" as the leading train moves down the line. Having a certain level of knowledge of signals does greatly enhance your trainwatching experience.
Lithonia Operator I've now come to the conclusion that all I need to do is: Get hired by a railroad in T&E service, and memorize the rulebook. Then I need to work there for a year or so, to learn how things work in the real world.
And, you have to learn exactly what a given signal indication means in each specific location...
This is one reason crews need to be qualified on their territory.
Granted, the vast majority of signal indications mean the same thing all over a given railroad (historical considerations notwithstanding), but there can be exceptions.
Once you get the basics down, having a signal chart that applies to the railroad where you're watching will generally get you where you need to be.
I have the chart for the B&O CPLs on "speed dial" on my computer as I watch Deshler on-line. F'rinstance, sometimes the dispatcher will line another train up immediately behind one that has just passed. Viewers can then watch one of the signals go from "restricting" to "approach" to "clear" as the leading train moves down the line.
Having a certain level of knowledge of signals does greatly enhance your trainwatching experience.
In some cases approachng terminals you may also need a copy of the Timetable Special Instructions for the territory - some places have instructions that state that if the Signal at X displays less than Clear and you have Y long train - stop at the signal and communicate with the Yardmaster to see what his intentions are.
Lithonia OperatorI've now come to the conclusion that all I need to do is: Get hired by a railroad in T&E service, and memorize the rulebook. Then I need to work there for a year or so, to learn how things work in the real world.
Lithonia Operator I started this thread expressing my desire to be able to look at signals and discern exactly what the situation is. I've now come to the conclusion that all I need to do is: Get hired by a railroad in T&E service, and memorize the rulebook. Then I need to work there for a year or so, to learn how things work in the real world. Then I need to do the same with all the other railoads in the US. And Canada. Since I turn 70 in two weeks, maybe I need to kick this plan into high gear ... Seriously, guys, I've learned a lot from you all, and the links you've provided. Thanks. But it's a whole lot more complicated than I had ever imagined.
I started this thread expressing my desire to be able to look at signals and discern exactly what the situation is.
I've now come to the conclusion that all I need to do is: Get hired by a railroad in T&E service, and memorize the rulebook. Then I need to work there for a year or so, to learn how things work in the real world.
Then I need to do the same with all the other railoads in the US. And Canada.
Since I turn 70 in two weeks, maybe I need to kick this plan into high gear ...
Seriously, guys, I've learned a lot from you all, and the links you've provided. Thanks. But it's a whole lot more complicated than I had ever imagined.
You can still have the experience if you should ride VIA between Toronto and Vancouver--and (five years ago) between Jasper and Prince Rupert.
Johnny
Lithonia Operator Guys, I really appreciate the input, and I'm really not trying to be a pain in the butt (honest), but ... Why would you display a green over two reds, when you could display three greens in a vertical stack, if the meaning is "clear?" You CAN make all the heads show green, right? Or not?
Guys, I really appreciate the input, and I'm really not trying to be a pain in the butt (honest), but ...
Why would you display a green over two reds, when you could display three greens in a vertical stack, if the meaning is "clear?" You CAN make all the heads show green, right? Or not?
Well, in Sweden they do just that all the time: https://en.wikipedia.org/wiki/Swedish_railway_signalling
unfortunately, they use them in the exact opposite of "fail-safe" operation: more restrictive indications are conveyed by MORE green lights.
jeffhergert RKFarms Just a note to those interessted-there are a couple of series of videos on youtube that I found to be helpful in interpreting signals. One is Railroad Signals, reading and meanings, part 1: The basic three light system (4 segments) and How to Read CSX Signals (2 segments) and a few others that come up in a search. I found going through these a few time and relating this information to local signals to be very helpful. Experts might find errors in these but for a civilian they are very helpful. PR It should be noted that his three head CTC description is speed signalling. Some use route signalling or a hybrid combination of both. He also, being a Canadian railroader uses Canadian rule book signal names. A red over green over red (or just red over green) to me, and others, is a Diverging Clear. Proceed on diverging route, not exceeding the prescribed speed of the turnout (switch). We have places where the prescribed speed is up to 60 mph. Jeff
RKFarms Just a note to those interessted-there are a couple of series of videos on youtube that I found to be helpful in interpreting signals. One is Railroad Signals, reading and meanings, part 1: The basic three light system (4 segments) and How to Read CSX Signals (2 segments) and a few others that come up in a search. I found going through these a few time and relating this information to local signals to be very helpful. Experts might find errors in these but for a civilian they are very helpful. PR
Just a note to those interessted-there are a couple of series of videos on youtube that I found to be helpful in interpreting signals. One is Railroad Signals, reading and meanings, part 1: The basic three light system (4 segments) and How to Read CSX Signals (2 segments) and a few others that come up in a search. I found going through these a few time and relating this information to local signals to be very helpful. Experts might find errors in these but for a civilian they are very helpful.
PR
It should be noted that his three head CTC description is speed signalling. Some use route signalling or a hybrid combination of both. He also, being a Canadian railroader uses Canadian rule book signal names.
A red over green over red (or just red over green) to me, and others, is a Diverging Clear. Proceed on diverging route, not exceeding the prescribed speed of the turnout (switch). We have places where the prescribed speed is up to 60 mph.
Thanks, Jeff. I thought you meant that those two different aspects meant the same thing on the SAME railroad.
Now, I do know that mergers have muddied the water. For example, on NS things will be different depending on whether the line was former SOU or NW. Lots of similar mongrel situations must exist on all the Class 1s, I would assume.
jeffhergertDifferent railroads, different ideas on signals and their meanings.
That was the root cause of a collision (Amtrak Pere Marquette?) near Chicago a few years ago. The engineer physically changed railroads (if you will), but forgot to do so mentally and incorrectly interpreted a signal to be less restrictive that it was.
Interpreting the B&O CPLs isn't difficult - top marker lit, high speed, bottom marker lit, low speed. Side markers lit usually indicates a diverging movement.
As with today's signals, any aspect not needed for a give location will not have the marker needed for that aspect. None of the Deshler CPLs have lunar in the main disk, and I don't think any have the right-hand (yellow) markers, top or bottom.
Viewers of the Deshler cams will note that the signal controlling movements off the southwest transfer and on to the EW main has only one lamp (red) in the top head, and only two (red and amber, I believe) in the middle head. The bottom head has all three lamps.
Lithonia Operator Jeff, you mentioned that there are two different combinations meaning Diverging Clear. Why would there be any more than one aspect needed for a particular meaning?
Jeff, you mentioned that there are two different combinations meaning Diverging Clear. Why would there be any more than one aspect needed for a particular meaning?
Different railroads, different ideas on signals and their meanings. Signals are not a one size fits all situation anymore. They used to appear in the rule books and were more common between those that used the same rule book. Now they appear in the system special instructions, with a rule number, but can and do vary between railroads using the same book.
Look at the charts for both UP and BNSF. Both use GCOR, but some signals are different.
DeggestyFrom what I did see, it seemed that the heads themselves were the same, with no center light, and green lights, yelow lights, and red lights in the proper position.
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blue streak 1Note had someone on old N&W RR state that signals were changed to the color lights when last trainman on each subdivision retired who was color blind. Could never confirm that statement ?
It is my understanding that the change to CPL signal heads on the N&W came about a short while after train #95 headed south ran into the side of northbound passenger train #2 that was hanging out of the siding at the south end of Cloverdale, Va. It was found that the governing southbound signal at the north end of Cloverdale siding had been worked on by a signal maintainer earlier in the day and that PL signal head actually fell down into a position that made the "Approach" indication look like a clear indication.
Thanks ... Trying to play along at home .
rdamon LO, are you talking R/G/R and R/G?
LO, are you talking R/G/R and R/G?
Yes, because those are the ones Jeff mentioned.
I see there is also a Diverging Clear Limited and Diverging Approach Clear Fifty as well ..
https://signals.jovet.net/rules/UPRR%20Signal%20Rules.pdf
Thanks to all for the great information. I will watch the YT video too when I get time. And thanks to those who answered my question about what aspects mean. This is all very confusing and glad the crew have it figured out. Have a FB friend who trained to be Amtrak conductor and she had to learn multiple stuff about signals, as they use many different roads to travel on and have to know them. Easier "back in the day" when passenger trains only traveled on their "home road" and only needed to know that one. I can see why a pilot engine is needed when you leave your usual route.
RKF, thanks for that info. I've only watched the very beginning of the first video so far, but it looks like that series will be very instructive.
Deggesty As late as 1951, the AGS and NO&NE still used upper quadrant semaphores. Standing at the back of #43, I enjoyed watching the NB signals clear as I traveled from Birmingham to New Orleans. As I recall, when the signals were upgraded, searchlight signals were installed.
As late as 1951, the AGS and NO&NE still used upper quadrant semaphores. Standing at the back of #43, I enjoyed watching the NB signals clear as I traveled from Birmingham to New Orleans. As I recall, when the signals were upgraded, searchlight signals were installed.
Yes.. AGS ( Alabama Great Southern rr ) Chattanooga - Meridian, Ms and NONE ( New Orleans & North East ) Meridian - New Orleans. and just for grins SOU subsidiary LSO ( Louiana Southern Railway) New Orleans - south on east side of Mississippi.
There is two mainly operating systems of signaling. AC and DC. The DC system was usually added to the communication line telegraph and telephone pole lines later. For expediency the signal system was added under the communications lines pole arms on a separate cross arm. The signal system pole arm would have the 4400 V (may have been different at some RRs ) power lines mounted on the end of the arm. Power lines were either 2 wire single phase or 3 wire 3 phase. No neutral. Then the DC signal lines would be placed on opposite sides of the cross arm. It could be just 3 wires out in the boonies but in locations where there were grade crossing with fixed distance activation there would be more wires ( usually 1 or 2 ) from isolation point to crossing signal bungalow. Then there would be more wires for special circumstances. This arragement was essentially on single track ABS with or without CTC.
When CTC was installed the 2 wires for CTC control would usually be placed on the power line side of the cross arm. At most locations where power was needed a small step down transformer would usually be mounted under the power line connecting to 2 of the phases of 4400 V power line. Old SP signal systems good example.
Now AC signaling on single track was different animal. SOU RR used mostly 3 light vertical heads. Sou RR had a separate pole line on opposide side of the tracks from the communication lines. As such they had three phase power on top in a triangle design ( no neutral ) . Cross arm for the 2 outside phases was rather short ( about 2 - 1/2 feet ). The phase positions were rotated about every mile (?) to reduce possible interferrence. That was to reduce and hopefully prevent AC signal hum on the communication lines. Then a cross arm was installed below the power lines to carry the AC signaling lines. Again usually 3 AC signaling wires but more at crossings and special circumstances. Very small Transformers were pole mounted just below power lines like power companys do today.
Almost forgot At sidings there would be an extra 1 or 2 wires between ends of sidings to activate an approach signal when block at far end had an approaching train. So if trains were approaching a siding from both directions both ends would show approach ( Y on three light masts and right diagonal on position masts ). an approching train would turn far signal at siding stop (red) once a train was between the siding and first signal before siding. On double track current of traffic sections there would be no signal lines needed except at grade crossing or other special locations . If CTC was added to the double track then a com line cross arm would be added if none existed with CTC wires. Many pictures of the SOU double tracks ATL - Alexander, VA show that configuration. How SOU did on its various other lines like the CHA - Cincinnatti ( CNO&TP ) sub is unknown though some subs used search light type signals.
A partial list of the systems similar to SOU was MP, T&P, Kiwi rail (maybe FEC ? ).
As Sou and other RRs installed the sonic type of grade crossing signals they used commercial power . That lessened the need for RR power and eventually power lines once new rail signaling was introduced on a line.
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