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To gap or not to gap (or where to gap)… that is the question.

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To gap or not to gap (or where to gap)… that is the question.
Posted by GEORGE WARNER on Monday, February 6, 2017 7:37 PM

I'm about ready to start laying track for the South San Francisco stock yard / Caltrain station: <http://geowarblog.freesite.website/blog/the-new-improved-plan> (last photo)… but I'm wondering where should I gap blocks? I'm running DCC with JMRI so these blocks are more for locating trains than isolating them. I initially thought "all turnout to non-turnout transisions…" but is that necessary? For example the red/green lines are the North & South bound Caltrain lines… I could just gap before each turnout (in the travel direction) and between the red & green turnouts (in other words: the red/green turnouts don't need their own blocks). But does this also work for the yellow (yard) turnouts? Or should they all be together (isolated by the tracks between them)? Advice welcome.

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Posted by Steven Otte on Tuesday, February 7, 2017 8:46 AM

If you don't need to turn off individual tracks to park trains (or just silence idling sound-equipped locomotives), there's no reason the entire yard couldn't be a single block. The rule is, power to turnouts must always be fed from the point end. So if you gap the rails just after the double crossover, and feed power from the point ends of those first two turnouts, you should be fine. If you use power-routing turnouts, you can even isolate tracks (if needed) by simply throwing the points.

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Posted by GEORGE WARNER on Tuesday, February 7, 2017 11:56 AM

The double cross over is in the San Francisco yard… and is already gapped as one single block. My question is about the South San Francisco yard (upper wall of room/image). If I make the whole thing one block then the CalTrain commute train can't get thru the yard while switchers are working. And I do want to properly signal the red/grean (north-/south-bound) mainlines eventually. Perhaps it should be blocked as four zones: north & south bound (red & green), north & south yards (yellow)?

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Posted by Steven Otte on Tuesday, February 7, 2017 1:31 PM

I thought you were talking about the stub-ended passenger terminal at the bottom. My bad.

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Posted by Steven Otte on Tuesday, February 7, 2017 1:33 PM

Also, if you're using DCC, there's really no such thing as a "block." Trains can move through any section of track independent of each other. As long as it's wired so there are no short circuits, it can be all one power district, and you can run as many trains through it at once as there are tracks.

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Posted by carl425 on Tuesday, February 7, 2017 1:38 PM

Steven Otte
Also, if you're using DCC, there's really no such thing as a "block."

Of course there is.  Blocks are required to do detection, which based on the OP, he is interested in doing. 

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Posted by 7j43k on Tuesday, February 7, 2017 2:38 PM

For signaling purposes, you divide the mainline into enough blocks such that operation is efficient.  Yards are not signaled (generally).

For example, that whole lower peninsula would likely only have signals at the tunnel entrances.  I think the peninsula would be treated as an interlocking, in that it would likely have a tower and an operator who would, among other things be controlling the signals facing incoming trains.  Signals facing departing trains would be most likely ABS controlled.  

For the upper section, you can either have it be all-yard, and then it would have no signals.  Or you can have a main.  And that main track(s) will be signaled.  The former would be quite unlikely where commuter trains run. 

 

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Posted by GEORGE WARNER on Tuesday, February 7, 2017 2:52 PM

The peninsula has a tower… but it's been unmanned since '95 when it's duties were transerred to San Jose. The mains thru SSF are signaled at each end. Since there's only the two cross overs (one middle & one a north-east end) I figured those would be the places to gap the mains.

So, is the consensus that the SSF yards be un-gapped (other than from the mains)?

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Posted by GEORGE WARNER on Tuesday, February 7, 2017 3:24 PM

The double cross over is in the San Francisco yard… and is already gapped as one single block. My question is about the South San Francisco yard (upper wall of room/image). If I make the whole thing one block then the CalTrain commute train can't get thru the yard while switchers are working. And I do want to properly signal the red/grean (north-/south-bound) mainlines eventually. Perhaps it should be blocked as four zones: north & south bound (red & green), north & south yards (yellow)?

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Posted by carl425 on Tuesday, February 7, 2017 3:27 PM

7j43k
For signaling purposes, you divide the mainline into enough blocks such that operation is efficient.  Yards are not signaled (generally).

Agreed.

The OP however did not mention signaling.  He said:

GEORGE WARNER
I'm running DCC with JMRI so these blocks are more for locating trains than isolating them.

which would require all the yard tracks to be detected independently.

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Posted by 7j43k on Tuesday, February 7, 2017 4:21 PM

OK.

So we're going with blocks that are NOT for signaling.

The OP did say "...these blocks are more for locating trains than isolating them."

Locating trains?  I thought you just looked "over there" to see.  How is dividing the layout into about 4-6 blocks going to "locate" a train?

 

Perhaps OP is not expressing himself clearly.  Or maybe I'm dropping the ball, here.

 

 

 

Ed

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Posted by carl425 on Tuesday, February 7, 2017 4:41 PM

7j43k
How is dividing the layout into about 4-6 blocks going to "locate" a train?

Having learned that JMRI has "train tracking" last week (thanks Randy) I naturally assumed that's what OP was talking about.  Lacking complete information from the OP, we are left to assume his intention.  It's of course likely that one or both of us is assuming incorrectly.

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Posted by 7j43k on Tuesday, February 7, 2017 5:34 PM

carl425

It's of course likely that one or both of us is assuming incorrectly.

 

 

I've been known to do that.  And do it quite well, actually.

 

I do think that the bright move would be to block it for signaling, and let the cool JMRI ap deal with those.

 

Ed

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Posted by BigDaddy on Tuesday, February 7, 2017 5:55 PM

Newbie's always leave a lot to our imagination on their early posts, no offense intended, welcome to the forum.

All I can add is his track plan

Henry

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Posted by 7j43k on Tuesday, February 7, 2017 6:47 PM

Actually, I like the track plan.  Looks very nice.  Of course, it's sorta augmented 'cause I live just a few miles away.  And remember Trainmasters on the engine ready tracks.

 

Ed

 

Ed

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Posted by GEORGE WARNER on Thursday, February 9, 2017 12:07 PM

Being a noob, I assumed that everyone knew that JMRI does "train tracking" (FYI: with RFID readers it can actually even track every car!). That is what I'm blocking for.

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Posted by GEORGE WARNER on Thursday, February 9, 2017 12:10 PM

Thanks for adding the track plan… I tried using the "Insert/edit image" button to add it to my message but it never worked for me… I tried the "Source" as a path to a local file on my system and as a URL to it on my web site. Ether way it never appeared in my messages.

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