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.
Jeff
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.
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...
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.
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.
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.
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.
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 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.
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.
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.
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.
Never too old to have a happy childhood!
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.
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
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.
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
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.
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.
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...
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.
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.
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.
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