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How to signal parallel mainlines?

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  • Member since
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  • From: Frankfort, Indiana
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How to signal parallel mainlines?
Posted by Morpar on Sunday, September 24, 2023 2:01 PM

I understand up until the 1980's when a railroad put signals up they had to be on the right side of the line based upon the position of the engineer being able to see it. So when there were 2 single track lines running side-by-side how was this handled? I have seen signal bridges and cantilevered arms, but did any railroads put 2 signal heads on a single pole similar to the Atlas HO scale model (here's an example https://www.micromark.com/Atlas-Type-G-Double-Head-Signal-HO-Scale)? I know it's my railroad, but I want to try to be as protypical as practical. 

Good Luck, Morpar

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  • From: Collinwood, Ohio, USA
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Posted by gmpullman on Sunday, September 24, 2023 3:49 PM

Multiple signals on one mast are necessary to convey what particular aspect is required for a certain 'rule' needed to convey train movement. Each aspect corresponds to a particular rule for train movement.

 Signal NYC Type G by Edmund, on Flickr

 NYC_GRS_G Signal by Edmund, on Flickr

If a signal was mounted with another track between it and the track signaled a 'doll arm' or sometimes a blue light is used to signify the unsignaled track.

 NYC Signal 1956 by Edmund, on Flickr

 NYC Signal by Todd Dillon, on Flickr

Another example:

 Norwood Ma. station interlocking. by Brian M, on Flickr

Also note that if visibility is a problem (cars on the intervening track) the mast height is adjusted appropriately.

Good Luck, Ed

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Posted by Morpar on Sunday, September 24, 2023 6:18 PM

Great information Ed, thanks! I love that there is usually a prototype for everything, you just have to find out who knows where to find it.

Good Luck, Morpar

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  • From: Omaha, NE
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Posted by dehusman on Sunday, September 24, 2023 11:39 PM

Morpar
So when there were 2 single track lines running side-by-side how was this handled?

Don't understand the question.

You can have 2 main tracks, that is two tracks belonging to the same railroad running side by side.

If it's two single tracks owned by the same railroad, totally separate lines then normally they will each have their own right of ways and own signals.  That is a fairly unusual situation, in most cases after a short distance the two lines diverege and each goes on its own route to different places.

If it's two single tracks owned by the different railroads, totally separate lines then normally they will definitely each have their own right of ways and own signals.

Morpar
but did any railroads put 2 signal heads on a single pole similar to the Atlas HO scale model

That isn't for two lines, that is ONE signal with two heads for a single track.  Both heads are used for the same track.  Some signal indications require more than one light to convey the meaning.  For example, a single green signal is a "clear", meaning proceed while a red over a green is "diverging clear", which means proceed on the diverging route (that means the train is approaching a switch and will take the diverging, curved route, through the switch and the track is clear 2-3 blocks ahead on that route.)

Dave H. Painted side goes up. My website : wnbranch.com

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Posted by gregc on Monday, September 25, 2023 6:17 AM

Morpar
I understand up until the 1980's when a railroad put signals up they had to be on the right side of the line based upon the position of the engineer being able to see it. So when there were 2 single track lines running side-by-side how was this handled?

i thought this was about where the signal were placed.

we have twin signals on the layout similar to those in the photo monuted on the right side of the track (the one on left is facing  away)

but i see that csx double tracks near and in cumberaland today have signals on the both right and left side of the track.

greg - Philadelphia & Reading / Reading

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Posted by Morpar on Monday, September 25, 2023 7:27 AM

Greg this looks similar to what I am going to model. Both lines are set up to have trains running in both directions, so they would need signals on each side of the tracks. And with the way the signals are mounted to the poles the crews can tell which track the signals are for.

Good Luck, Morpar

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  • From: lavale, md
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Posted by gregc on Monday, September 25, 2023 9:16 AM

maybe not clear, the photo shows signals facing opposite directions on the right side of the tracks when seen by the crew.

there are 2 signals on each, one for each track.

here's a picture from the layout before the signal on the left was moved to the opposite end of the tunnel

greg - Philadelphia & Reading / Reading

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Posted by cv_acr on Monday, September 25, 2023 10:24 AM

Morpar
did any railroads put 2 signal heads on a single pole

Multiple signal heads on the same pole ("mast") are read as a single signal, NOT used for multiple tracks. You do this when you need to display more indications other than "Stop", "Approach", and "Clear", like "Slow Clear" or "Approach Medium". (Find signal charts specific to the railroad you're following as the specific usage may vary.)

For multiple tracks, use bridge or bracket structures in order to mount multiple masts. In same cases if signals absolutely had to be placed to the left of the track it would be specifically noted in the operating timetable. (And only done if there was no additional track to the left.)

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Posted by cv_acr on Monday, September 25, 2023 10:29 AM

This is from a Canadian rulebook, describing signal placement, but is similar or identical to most US rulebooks in this regard:

http://waterlooregionmodelrailwayclub.ca/operations/1962-ucor/r246/

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Posted by wjstix on Monday, September 25, 2023 11:19 AM

If I understand the OP's question correctly, I believe he's asking about signalling a double-track mainline in the days before railroads were allowed to put a signal on the left side of the track - back when signals had to above or to the right of the track. The answer depends on how the railroad used the tracks.

If the railroad often used both tracks for both directions - i.e., didn't exclusively use one track for westbound and one for eastbound - they would use a signal bridge of some type to show full signalling for both tracks.

If the railroad used each track for an exclusive direction, it would set up single-mast signals only for the direction of travel. For the other track, they might use dwarf signals (signals down at track level) set between the rail lines, for the rare instances where the railroad had to run on the 'wrong main'. 

Stix

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