Eastern Railroad Discussion > NS Signal aspect questions

Can anybody in the know tell me who sets the signal aspects in 261?

I've seen the 261 signal for westbound trains just before the main reaches Gurley showing Yellow over Red and the next signal at "Asa" Red over Red over Red. At the same time the eastbound signal at "Brock" at the other end of the long siding was Red over Red over Red Moving further west on the main, the eastbound signal along Morring Road where it 261 begins was Yellow over Red.

It seems to me that the signals are intended to be seen by and to convey messages to oncoming trains, so where are they? They never seem to show up.

TIA,

Fritz in HSV, AL

navy5717th Wrote:
-------------------------------------------------------
> Can anybody in the know tell me who sets the
> signal aspects in 261?
>
> I've seen the 261 signal for westbound trains just
> before the main reaches Gurley showing Yellow over
> Red and the next signal at "Asa" Red over Red over
> Red. At the same time the eastbound signal at
> "Brock" at the other end of the long siding was
> Red over Red over Red Moving further west on the
> main, the eastbound signal along Morring Road
> where it 261 begins was Yellow over Red.
>
> It seems to me that the signals are intended to be
> seen by and to convey messages to oncoming trains,
> so where are they? They never seem to show up.
>
> TIA,
>
> Fritz in HSV, AL


Yellow over red is approach. Meand b e prepared to stop at next signal. That next signal is stop, which the yellow over red conveys. Looking the other way as you said is the same as I wrote before.

261 territory home signals are controlled by a dispatcher or tower operator, for the most part.
That's why they all it "Centralized Traffic Control". The railroad is controlled from a centralized location. There are usually "intermediate" signals in CTC territory too, which are automatic signals which only convey the track condition ahead. They are not controlled from the central location.

As for the signals you are looking at, the red over red over red are home signals, controlled from
a central location. The yellow over red signals are most likely automatics, which are just are just telling you that the next signal is red. Easy way to tell (generalized) if a 2 head signal is a home signal or automatic...if the light heads are staggered, then its an automatic. Lights straight over each other usually means a home signal. Also, the more sure-fire way to tell is that home signals do not have number plates (usually located somewhere on the signal mast) and automatic signals have number plates.

Of course, there are always exceptions, but that's the general rule.



Edited 1 time(s). Last edit at 06/25/11 16:26 by pdt.

The switches at the locations you mention are controlled by the dispatcher in Birmingham. These can be described at CTC "islands" in otherwise ABS territory. When the dispatcher is not lined up at Gurley or Asa, you'll have the red over red at those locations. The signal before Gurley and the signal before Asa are giving an approach indication automatically since the next signal in each case is "stop." Depending on whether these are controlled or signalled sidings, the sigals you mention as displaying yellow over red are going to change when the dispatcher lines up at Gurley or Asa. Without complicating things too much, if a train is lined down the main at Gurley or Asa, you're probably going to get a clear at the signal BEFORE the signal at the siding switch (or could get an advance approach (yellow over yellow) depending on stopping distances). If the train is lined into the siding then you're most likely going to see either an approach diverging (yellow over green) or a restricting (red over yellow IF there is a space left in between the two signal heads where another signal could be placed). A red over red over yellow is also a restricting signal, meaning you need to be at restricted speed by the time you get to the next signal. I'm not familiar with Asa or Gurley, so can't pinpoint this for you. But in short, when the DS lines up at Asa or Gurley, the intermediate signals you usually see displaying yellow are going to change indications.


navy5717th Wrote:
-------------------------------------------------------
> Can anybody in the know tell me who sets the
> signal aspects in 261?
>
> I've seen the 261 signal for westbound trains just
> before the main reaches Gurley showing Yellow over
> Red and the next signal at "Asa" Red over Red over
> Red. At the same time the eastbound signal at
> "Brock" at the other end of the long siding was
> Red over Red over Red Moving further west on the
> main, the eastbound signal along Morring Road
> where it 261 begins was Yellow over Red.
>
> It seems to me that the signals are intended to be
> seen by and to convey messages to oncoming trains,
> so where are they? They never seem to show up.
>
> TIA,
>
> Fritz in HSV, AL

You are seeing the signals at their default indications. There may or may not be a train approaching when those indications are displayed. Even if you see a green on a home signal, the train may not be close. Sometimes the dispatcher lines way ahead if there is no other traffic. It's only a guessing game at best reading signals in the field.

From a railfanning perspective, knowing the "default" indications of these approach signals can be useful. For example... You're in single track territory, and you're looking at an eastbound intermediate signal that shows Y/R leading to a home signal protecting either double track or a siding (default indications being all red). As you're sitting there, waiting, you see the signal indication change to:

R/R - A train is likely lined coming westbound past your position (assuming that no train just went by eastbound)
G/R - A train is lined eastbound, not taking the diverging route (not taking the siding)
Y/G - A train is lined eastbound, taking the diverging route

You mentioned three aspects (R/R/R). That usually means there's a third possible route - i.e. a crossover to a parallel track, then onto a leg of a wye, or another line that goes off in a different direction.

Hope this all has helped!

-Eric



Edited 2 time(s). Last edit at 06/26/11 09:17 by sou2601.

sou2601 Wrote:
-------------------------------------------------------
> From a railfanning perspective, knowing the
> "default" indications of these approach signals
> can be useful. For example... You're in single
> track territory, and you're looking at an
> eastbound intermediate signal that shows Y/R
> leading to a home signal protecting either double
> track or a siding (default indications being all
> red). As you're sitting there, waiting, you see
> the signal indication change to:
>
> R/R - A train is likely lined coming westbound
> past your position (assuming that no train just
> went by eastbound)
> G/R - A train is lined eastbound, not taking the
> diverging route (not taking the siding)
> Y/G - A train is lined eastbound, taking the
> diverging route
>
> You mentioned three aspects (R/R/R). That usually
> means there's a third possible route - i.e. a
> crossover to a parallel track, then onto a leg of
> a wye, or another line that goes off in a
> different direction.

Be careful about your use of the word "aspect" here. "Aspect" means the combination of colors and the meaning they represent, not the individual signal heads.

Also, three-head signals don't necessarily mean there's a possible different route, especially on railroads that use speed signalling instead of route signalling.

Otherwise, though, you're spot on: knowing signals' "default" aspects can be very useful for train forecasting.

one of the best sites to explain signals is http://www.alkrug.vcn.com/home.html
do a little searching here

To everybody who answered, Thank you.

Your response were all excellent. They'll help alleviate my previous frustration when I hope to see a train because of the signals I see -- and none shows up.
This is a great forum to belong to. It's people like you who make railfanning such an enjoyable pastime.

Thanks again,

Fritz in HSV, AL