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what is an "O.S" section?

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what is an "O.S" section?
Posted by gregc on Tuesday, February 15, 2022 5:01 AM

is it "on sheet" or "on switch"?

i've read that a station manager (?) will note the arrival/passing/departure of a train at a particular station on a record sheet.

from a signaling/interlocking perspective, it seems to refer to a relatively short block with one or more switches used to recognize that a train is on the switch to prevent the switch from being thrown while occupied.

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Posted by wjstix on Tuesday, February 15, 2022 8:51 AM

I've heard "O.S." as meaning "On Sheet", meaning that a train has passed a particular station or tower and has been recorded 'on the sheet' as having passed at such-and-such a time. I've not heard "O.S. Section" before, so not sure what that would mean? 

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Posted by cv_acr on Tuesday, February 15, 2022 9:59 AM

Two different things in your question.

With TT/TO an "OS" is a report from the operator to the dispatcher that a particular train has passed. The operator would ring up the dispatcher and announce himself with the hail "OS <station name>" and then they would report the train information. The rule book identifies that "OS" is a proscribed abbreviation* to use when reporting, but not a history for why those letters. "On sheet" has long been touted as a possible original meaning (as the dispatcher will use the reported sighting to update the train's progress by writing in the time on his train sheet). "Operator sighting" might also be logical. Or maybe "operator station", as the operator calls in with "OS <station>" to identify himself...

(* Literally the only reference in my rulebook is under "approved abbreviations" [to be used in orders and/or other communications]: OS = Train Report)

"OS Section".... I have heard people use that term to refer to the short block in an interlocked CTC control point. (i.e. usually just the length of the controlled siding switch) Not sure how that gets its name exactly, other than perhaps from the train crossing through this point is what the dispatcher would be able to use to actually mark a train's position/progress - i.e. since the track block is so short it's essentially a point reference, and the CTC machine/computer will show the train occupying and clearing the point, essentially providing the dispatcher his "OS". (Trackside operators don't exist anymore...)

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Posted by dehusman on Tuesday, February 15, 2022 10:18 AM

In signaling, usually refers to CTC or intelockings, it is typically a section of track that includes a switch that indicates occupancy of the switch.

If the switch is occupined then the train has left the station, OS'd.  Which translation you want to apply is immaterial, they all have the same effective meaning, the train has "left" the station.

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Posted by dehusman on Tuesday, February 15, 2022 10:20 AM

wjstix
I've heard "O.S." as meaning "On Sheet"

There are about a half dozen different translations of what "OS" means.  Really doesn't matter which translation you use, the effective meaning is the same, the train has departed the station.

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Posted by gregc on Tuesday, February 15, 2022 2:12 PM

i thought it does matter from an interlocking point of view.

if there's a junction with a single CTC controlled switch, wouldn't control of the switch be inhibited if there was a block just covering the switch that was occupied?

signals would depend on the occupancies of blocks on either sides of the switch

such a situation would have nothing related to being "on sheet"

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Posted by cv_acr on Tuesday, February 15, 2022 2:16 PM

gregc

i thought it does matter from an interlocking point of view.

if there's a junction with a single CTC controlled switch, wouldn't control of the switch be inhibited if there was a block just covering the switch that was occupied?

signals would depend on the occupancies of blocks on either sides of the switch

such a situation would have nothing rela ted to being "on sheet"

 

He's saying whatever the original words that leant themselves to the "O.S." shorthand for "train report" doesn't make any difference.

That has nothing to do with how the interlocking locks things out.

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Posted by gregc on Tuesday, February 15, 2022 4:52 PM

cv_acr
He's saying whatever the original words that leant themselves to the "O.S." shorthand for "train report" doesn't make any difference.

That has nothing to do with how the interlocking locks things out.

Dave said it boils down to "the train has departed the station".   

but the situation i described at a junction isn't at a station, or is it?

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Posted by jeffhergert on Tuesday, February 15, 2022 9:22 PM

A few years ago, the UP site had something, I don't remember what the actual discussion was about, where they said OS meant "over switch"  This probably came from a person who only knew OS from the OS sections of control points.  Someone who never knew about open depots/towers and telegraph calls, etc.

There were enough comments from those who DID remember and the majority consensus was that OS derived from "on sheet."  The time(s) entered on a station/tower's record of train movement.  I fall into that category.  

Does it really matter now what the telegraph call derived from?  

When a train arrives at it's terminating station.  One from which it won't depart, how would the operator call the dispatcher to report it in?  "O S, (station)."

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Posted by dehusman on Tuesday, February 15, 2022 11:33 PM

gregc
if there's a junction with a single CTC controlled switch, wouldn't control of the switch be inhibited if there was a block just covering the switch that was occupied?

Yes. 

signals would depend on the occupancies of blocks on either sides of the switch such a situation would have nothing related to being "on sheet"

If the train moves over the switch then its has departed the station.  If there is a train movement its written on the "sheet" (train sheet or record of train movements) either manually or virtually.

gregc
Dave said it boils down to "the train has departed the station".    but the situation i described at a junction isn't at a station, or is it?

If it is a junction it will be named, if its named it's a station.

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Posted by gregc on Wednesday, February 16, 2022 7:16 AM

dehusman
In signaling, usually refers to CTC or intelockings, it is typically a section of track that includes a switch that indicates occupancy of the switch.

the diagram illustrates a siding, blocks (e.g. B20), switches (e.g. T23b) and three OS sections (e.g. OS2) are identified and used as separate inputs into interlocking logic

Dave's description suggests that the OS section may encompass the entire siding, not have 3 separate OS sections defined in the case below.   is this correct?

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Posted by dehusman on Wednesday, February 16, 2022 7:31 AM

gregc
Dave's description suggests that the OS section may encompass the entire siding, not have 3 separate OS sections defined in the case below.   is this correct?

How would you get that I said it encompasses the whole siding when I said it was the part with the switch?

T23a, T23b and T17 are the "OS sections".

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Posted by dehusman on Wednesday, February 16, 2022 7:45 AM

cv_acr
"OS Section".... I have heard people use that term to refer to the short block in an interlocked CTC control point. (i.e. usually just the length of the controlled siding switch) Not sure how that gets its name exactly, other than perhaps from the train crossing through this point is what the dispatcher would be able to use to actually mark a train's position/progress - i.e. since the track block is so short it's essentially a point reference, and the CTC machine/computer will show the train occupying and clearing the point, essentially providing the dispatcher his "OS".

Exactly.  Occupying the OS section provides a timestamp for train movements.  It reports an arrival, departure or passing time at that location.

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Posted by wjstix on Wednesday, February 16, 2022 9:04 AM

It would not be surprising if "OS" originally wasn't an abbreviation for "On Sheet" or anything else. It may have just been a code chosen to indicate a train had passed because it was easy to send and remember. Kinda like how SOS doesn't mean "Save Our Ship", it's just a real easy Morse code message to use - three dots, three dashes, three dots etc. etc.

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Posted by cv_acr on Wednesday, February 16, 2022 9:04 AM

gregc

but the situation i described at a junction isn't at a station, or is it?

"Station" is defined in the rulebook as ANY named point (with a station name sign). There doesn't even need to be ANYTHING else in terms of buildings, sidings or other switches there. 

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Posted by cv_acr on Wednesday, February 16, 2022 9:18 AM

wjstix

It may have just been a code chosen to indicate a train had passed because it was easy to send and remember. Kinda like how SOS doesn't mean "Save Our Ship", it's just a real easy Morse code message to use - three dots, three dashes, three dots etc. etc.

 

When you consider that the earliest operators all communicated via telegraph not telephone, this actually makes a lot of potential sense to me. The "_ _ _ ..." tones being a recognizable call.

Each operator station also had their own two-letter call symbols listed in the timetable.

Whatever the original meaning of "OS" (if it ever had one), it was over 100 years ago and it lost to time.

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Posted by dehusman on Wednesday, February 16, 2022 11:31 AM

I rather doubt the original meaning was "over switch" or "on switch" or "on signal" since a train can be OS'd by an operator where there are no signals or switches.

As other's have said, it really doesn't matter what the origin wasn, regardless of the translation is, an OS is a report of train movement, arrival, departure or passing.

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Posted by gregc on Wednesday, February 16, 2022 12:58 PM

dehusman
gregc
Dave's description suggests that the OS section may encompass the entire siding, not have 3 separate OS sections defined in the case below.   is this correct?

T23a, T23b and T17 are the "OS sections".

dehusman
Really doesn't matter which translation you use, the effective meaning is the same, the train has departed the station.

dehusman
an OS is a report of train movement, arrival, departure or passing.

ok

but now i'm curious, is each switch technically a station?

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Posted by cv_acr on Wednesday, February 16, 2022 1:04 PM

gregc
but now i'm curious, is each switch technically a station?

No.

I return to what I posted above:

"Station" is defined in the rulebook as any named point (with a station name sign).

Generally the entire siding and any other associated switches are associated with that station.

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Posted by dehusman on Wednesday, February 16, 2022 2:28 PM

cv_acr
"Station" is defined in the rulebook as any named point (with a station name sign).

Technically, any point named IN THE TIME TABLE.  

If its not named in the time table, then its not a station.

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Posted by dehusman on Wednesday, February 16, 2022 3:46 PM

gregc
but now i'm curious, is each switch technically a station?

If each switch is named separately in the time table, then yes.  If not, then no.

If the siding at Anna has East Anna and West Anna in the timetable (increasingly common in this GPS, measurement down to the nearest yard world we live in) then yes.  If the time table just lists Anna as the siding then no.

However as OS's go, the railroad will measure the departure of a westward train at Anna when it passes the west switch and the departure of an eastward train when it passes the East switch, regardless of whether or not the switches are "stations".

 

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Posted by fire5506 on Tuesday, July 26, 2022 2:04 PM

The original OS was for On Sheet. It was when the train arrived at or passed a manned location.

 Now with the the use of DTMF controlled turnouts there is an OS section that if anything is in that section the turnout will not operated until what ever is in the circuit is moved out.

SOS for ships has no words that it is short for. It picked because it was easy to key and wouldn't be confused with any other messages or words.

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Posted by wjstix on Wednesday, July 27, 2022 9:39 AM

fire5506

The original OS was for On Sheet. It was when the train arrived at

SOS for ships has no words that it is short for. It picked because it was easy to key and wouldn't be confused with any other messages or words.

Richard

 
Thanks for confirming what I said earlier. I've seen several references to OS originally meaning "On Sheet", nothing for any other meaning. BTW my dad was a telegrapher in the 1930s so I've always found telegraph history interesting.
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Posted by dehusman on Wednesday, July 27, 2022 10:33 AM

wjstix
Thanks for confirming what I said earlier. I've seen several references to OS originally meaning "On Sheet", nothing for any other meaning.

There is no official meaning for OS.  I have been told by the dispatchers it mean Out of Station.  There are a bunch of other meanings. For example in the modern CTC world, we called it an "Occupancy Section".

Since there is no "official" definition in any rule book, any definition is valid, it really doesn't matter, what's important is the practical meaning, that is a train has departed or passed.

Personally the more I read about it, the more I think it doesn't mean anything, its really just the shortest (ie fastest) two letter combination (dot dot   dot dot dot) you can send in telegraph code for the most common telegraph message.  Just like 19 and 31 really don't mean anything in train orders, that's just the codes they chose.

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Posted by jeffhergert on Wednesday, July 27, 2022 12:07 PM

dehusman

 

wjstix
Thanks for confirming what I said earlier. I've seen several references to OS originally meaning "On Sheet", nothing for any other meaning.

 

There is no official meaning for OS.  I have been told by the dispatchers it mean Out of Station.  There are a bunch of other meanings. For example in the modern CTC world, we called it an "Occupancy Section".

Since there is no "official" definition in any rule book, any definition is valid, it really doesn't matter, what's important is the practical meaning, that is a train has departed or passed.

Personally the more I read about it, the more I think it doesn't mean anything, its really just the shortest (ie fastest) two letter combination (dot dot   dot dot dot) you can send in telegraph code for the most common telegraph message.  Just like 19 and 31 really don't mean anything in train orders, that's just the codes they chose.

 

"Dot (space) dot / dot dot dot."  Two dots with no space is an "I" in American Morse.  There are a few other characters that also use a short space in the sequence.

Using "OS" wasn't just used by telegraph.  Operators using dispatcher's phones would say "OS (station)" when calling the dispatcher to make a report.

Jeff

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