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.
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 āback in the dayā when passenger trains only traveled on their āhome roadā and only needed to know that one. I can see why a pilot engine is needed when you leave your usual route.
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, 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?
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 āApproachā indication look like a clear indication.
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.
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 isnāt difficult - top marker lit, high speed, bottom marker lit, low speed. Side markers lit usually indicates a diverging movement.
As with todayās 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 donāt 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.
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).
I started this thread expressing my desire to be able to look at signals and discern exactly what the situation is.
Iāve 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 ā¦
Seriously, guys, Iāve learned a lot from you all, and the links youāve provided. Thanks. But itās a whole lot more complicated than I had ever imagined.
Itās a shame that it is no longer possible to sit in a dome and see the signals as your train approaches them. It was quite a sight to watch the signals on the Burlingtonās three track racetrack out of Chicagoāor see the signals as you came into Ogden on the UP from the east. Even watching lineside signals as you moved through the country was interesting, especially as you approached control points.
You can still have the experience if you should ride VIA between Toronto and Vancouverāand (five years ago) between Jasper and Prince Rupert.
And, you have to learn exactly what a given signal indication means in each specific locationā¦
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 youāre watching will generally get you where you need to be.
I have the chart for the B&O CPLs on āspeed dialā on my computer as I watch Deshler on-line. Fārinstance, 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 ārestrictingā to āapproachā to āclearā as the leading train moves down the line.
Having a certain level of knowledge of signals does greatly enhance your trainwatching experience.
It may be of interest here to mention the bible of British railway signalling, a book by L T C Rolt called āRed for Danger.ā 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 donāt 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.