Eastern Railroad Discussion > Help newbie understand signals

I’m a newbie railfan. Just learning. I’d like help understanding two signals I saw today. (I can’t figure how to paste the pic I took. Sorry about that.)

The main NS line btwn Atlanta and Charlotte runs through my little town. It’s double track. There is a signal tower across both tracks with signals on both tracks in both directions. Today, the SB signal for track M2 was yellow over red. I think that means “approach”. But at the same time the signal over the same track M2 facing NB was also yellow over red. What don’t I understand about the same signal facing opposite directions on the same track at the same time?

Posted from iPhone



Edited 1 time(s). Last edit at 10/02/22 11:14 by dadonatrain.

The next signals in either directions may be absolutes.
Meaning those signals are protecting interlockings (powered turnouts or crossovers) and those absolutes are displaying "stop". No trains are lined
in either direction.

Tom

Posted from Android

Some signals are part of a series ..... you'll have advance warning of what the 
NEXT signal might be displaying.

When controlling a long train, the LAST thing you want is a sudden signal
aspect that gets more restrictive...

So, advance, spaced,  signals give engineers speed modifications they should be obeying,
BEFORE they get to the next set of signals.....that could be miles down the 'road...
The next set of signals could be more 'informative'....

So, becoming an engineer over a territory means that you have to know, by heart,
what signals are in your territory, where they are located, and what 'aspects'  & combinations
of colors that you can expect to see.   That memorization process is called "being qualified"
over that specific territory.  All engineers must be qualified over that territory, in order to operate
trains.

That means that you have a ( memorized) complete mental picture of the "map" of the territory
that you're traversing: all it's bridges, road crossings, signals, junctions and stations ... and that
you can drive your trains through the darkest nights and in the fog....at maximum allowed speeds ....
and there's no 'feeling your way along..".  So that you can make the whole trip over the territory
by your perfect memory.  

That's the awesome responsibility of what "being qualified" means....both for conductors
and engineers,...they BOTH have to know the territory ....and conductors are good at knowing
where they are on railroad, simply by the feel of how the train behaves as its moving ..
even if they can't see out...

Being a qualified engineer is an AWESOME responsibility..  You generally get ONE 'learning trip'
over a territory, and you're expected to know, and remember all the signals' locations, and markers,
and what they mean,  of what lies ahead. ..like, maybe an open drawbridge, in you path !

Sometimes, district-qualified engineers are assigned to specific crews & trains as 'pilots' ----
to support an engineer that may be new to the territory..

I'm no "signals" expert , but in today's world they are becoming obsolete ---- being replaced
by in-cab displays, and "movable boundaries" to suit traffic frequency and other conditions
affecting flexible 'block' boundaries..

Juntions, though, aren't movable...they are absolutes..

And, as of today, not ALL loco cabs are equipped with the latest 
communications and signals displays ---- so, RED lights still mean 
BE STOPPED, do not violate the space beyond the red signal
that you're looking at!!

Welcome to TrainOrders...

Wes Camp
 



Edited 8 time(s). Last edit at 10/02/22 16:20 by wcamp1472.

The signals u are looking at apparently are automatics.  They only convey the condition of the track ahead, in cordination with the aspect on the following signal.    Signals are in both directions on same track as each track appears to be  signaled for CTC operation in both directions.

IDK if that answers your question....but most of the confusion in signalling is from not knowing the difference between automatic  signals, and home (controlled) signals. 

Thank you, all of you. This helped me a lot!

Posted from iPhone

I assume your territory is CTC?

Both of the signals you saw were automatics.
If an eastward train sees a yellow signal in front of it,
it knows the track is empty past the signal --
usually, empty at least as far as the next signal for
eastward trains. So if the track is empty for miles
in each direction, the westward and eastward signals
at one spot can show yellow at the same time.
(Or green.)

But some? all? of the time, once a dispatcher clears
a manual signal for a westward train, the eastward
automatic signals west of the train will go red, even
if the track immediately east of them is empty.

LOTS of info here:  https://railroadsignals.us/basics/basics1.htm

No, I didn't read it all! Good luck!

Fritz in MD

On former Southern lines like Atlanta-Charlotte, a newby's guide to essential signal indications:
G/R - proceed
Y/G - approach diverging (expect next signal R/G)
Y/Y - advance approach (expect next signal Y/R)
Y/R - approach (expect next signal R/R)
R/G - diverging clear
R/Y - diverging approach (expect next signal R/R)
R/R - stop
R/R/Y - restricted proceed

This is an oversimplification, but 80% of the time these signal indications will tell you what you want to know -- on former Southern lines. Every other RR has its own spin on things, sometimes very different (e.g. CSX).

Good thread.

Do railroads impose rules on how many territories an employee can be qualified on at the same time?

Can you maintain qualifications are three or four routes at the same time?

Posted from Android

Try a Google search for "CSX Signal Rules" (without the quotes).  Should connect you with a very nice pdf summary of CSX signals.

And to confuse matters further (at least in the last century), many (most?) eastern railroads used their signals to control the SPEED of trains, while many (most?) western railroads used their signals to control the DIRECTION of trains through interlockings, turnouts, sidings, branches, etc.

chakk Wrote:
-------------------------------------------------------
> And to confuse matters further (at least in the
> last century), many (most?) eastern railroads used
> their signals to control the SPEED of trains,
> while many (most?) western railroads used their
> signals to control the DIRECTION of trains through
> interlockings, turnouts, sidings, branches, etc.

The original poster asked about a nearby former Southern Railway line, which continue to use route signaling. 

To pick nits a little, both types govern the speed of trains. Route signaling requires the crew to know (to have memorized) the maximum speed of the train through turnouts on a diverging route. With speed signaling, the aspect (limited, medium, slow, etc.) indicates maximum allowable speed.

Paul Wilson
Arlington, VA

Even on Southern there could be indirect speed signaling. Consider two diverging tracks, one to the left followed immediately by one to the right (or vice versa), governed by the same signal with different speeds through the turnouts. The indications R/R/G and R/G/R would instruct the engineer which speed to adhere to. Of course the engineer still had to memorize the speeds.  

ctillnc Wrote:
-------------------------------------------------------
> Even on Southern there could be indirect speed
> signaling. Consider two diverging tracks, one to
> the left followed immediately by one to the right
> (or vice versa), governed by the same signal with
> different speeds through the turnouts. The
> indications R/R/G and R/G/R would instruct the
> engineer which speed to adhere to. Of course the
> engineer still had to memorize the speeds.  

And conversely...with speed signalling there is indirect route signalling...if you know you're territory you will have realized that coming down to certain diverging routes, you need a different speed depending on the route...so an Approach Limited may tell you to run Limited Speed, but you also know that you ONLY get that signal if you DIVERGE to a certain track at this location. A former RFE we had when Trip Optimized came out hated the fact we had to tell TO what track we were preparing to run, and that inevetitably we had to use signal indication to figure it out in time for TO to slow down, speed up or whatever...He'd rant...."we don't have directional signalling, only speed signalling!" I'd just look at him and say....'we do what we gotta do" 

I thought the key to the question here, though, was how the signals facing in opposite directions could both display an aspect more permissive than Stop and Proceed or Restricted Proceed.

One of the answers did address that. In a nutshell, the described scenario meant nothing was lined through in either direction, assuming this was in CTC territory (which is probably a valid assumption).

However, such a "conflict" could also occur in ABS (Automatic Block Signal) territory. In that case, the signals would stay clear until a movement occupied a certain distant block, after which the signal facing traffic that might oppose that movement would drop first to yellow and then to red as the movement got closer. Once the movement cleared the signal in question, it would clear up in the 'opposing' direction while progressing from red to yellow to green as the movement got farther away. Unless, of course, there were a following train, in which case the 'opposing' signal would behave as before depending on that following train's proximity.

 

Thanks for getting back to the question. Seeing green (or yellow) in both directions on the same track can be surprising. I initially learned signals on Automatic Permissive Block Signalling lines where one direction was left red (stop) based on the last train until an opposing train approached and the signals tumbled down to give green in the opposite direction. When the line was upgraded to CTC (with automatic signals between controlled interlockings) one could get green in both directions when no trains were present. It was a nice "no trains coming" indication for people trackside until they set the signals for "approach lit". Then all such signals went dark unless there was a train in the block the signal faced.
 

I’m the original poster. Still just a newbie, so a lot of what I still follow here is over my head, but I appreciate learning so bring it on! And I’m glad to have had something to do with starting what is clearly a stimulating thread for a lot of you experts! Seriously.

And I want to say thanks again especially for the answers that help me see the big picture. I never would have known that one signal not set just by its own immediate conditions but is dependent on or related to or influenced by what else is down the track. That’s obvious now that I think of it but I never would have without the answers I’m seeing here.

My original puzzlement was how can the signals tell trains going in opposite directions at the same time that’s ok? Now I get it.

Posted from iPhone

dadonatrain Wrote:
-------------------------------------------------------
> I’m the original poster. Still just a newbie,
> so a lot of what I still follow here is over my
> head, but I appreciate learning so bring it on!
> And I’m glad to have had something to do with
> starting what is clearly a stimulating thread for
> a lot of you experts! Seriously.
>
> And I want to say thanks again especially for the
> answers that help me see the big picture. I never
> would have known that one signal not set just by
> its own immediate conditions but is dependent on
> or related to or influenced by what else is down
> the track. That’s obvious now that I think of
> it but I never would have without the answers
> I’m seeing here.
>
> My original puzzlement was how can the signals
> tell trains going in opposite directions at the
> same time that’s ok? Now I get it.
>
> Posted from iPhone

The signals need to protect both directions so they are wired to do just that! There is also a case where if you are on one track the signals on the adjacent track will also light up....this helps you determine whether you are meeting another train, not that it's meant for that. And not a double track arrangements can do that...again...if it can they wired it that way. 

Lighting all signals helps the crew see if the lit signal is theirs or for another track. A typical two track railroad will have a signal on each side of the tracks. The train on the left track is looking for a signal on the left of the track a train on the right track is looking for a signal on the right side of the track. Where the signals are overhead they are placed right of center over the track they control. Approach lighting only the track with a train can lead to issues if there is a problem with the signal system. Imagine that you are running on the right hand track and see a green signal in the distance - from a distance you may not be able to tell if that signal is to the right or left of the track (or if above the track, which track the signal controls). One can assume that since they are only seeing one signal that it is for the track the train is running on.

Now add in an issue where the signal for the right track is dark for some reason and there is another train on track two potentially miles behind the train on track one. The crew may not notice that their signal is dark until it is too late. Meanwhile they operated their train based on the signal for the other track. It is a safer situation to light all signals at a location. The crew would see the signals for both tracks and know which one is theirs (left or right). If they saw only one signal they would know there was an issue and could slow their train until they determined if their signal was operating correctly.

I remember one location that I will call "misswired" where a train on track 1 would only approach light the signal on track 1 and a train on track 2 would approach light both tracks. An odd arrangement that I will assume was an error.