Author Topic: Occupancy Detection, signal systems, & blocks  (Read 1795 times)

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SOUPAC

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Occupancy Detection, signal systems, & blocks
« on: March 24, 2008, 01:10:18 PM »
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I'm currently laying track on my layout that will operate using DCC. I hear that this is the best time to install occupancy detection & signal circuitry if you intend to have operating signals — which I do. I am severely electronically impaired, thereby in search of a plug & play system. If it will require me understanding how it works, I'm afraid I don't have enough lifetime left to mess with it. Also, several questions come to mind...

1. What system do you recommend for the needed electronics and why?

2. My layout is in a basement that needs allocations for humidity changes (expansion
gaps) placed about every 10 feet. I certainly don't need a signal every ten feet for
the "block" I just created by gapping the track, so would it be correct to assume the
blocks needed for signaling would be defined by the secondary power bus and NOT
the track?

3. The layout will have 6 primary power districts (booster areas). I don't know if this is
a proper question or not, but I wonder if the electronics involved for signaling bridge
these zones seamlessly or will a system be required dedicated to each power
district?
RICK

John

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Re: Occupancy Detection, signal systems, & blocks
« Reply #1 on: March 24, 2008, 01:28:41 PM »
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What I do is run a separate bus for each detector section, then connect the track to that. This way, you can have all the expansions you need.

SOUPAC

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Re: Occupancy Detection, signal systems, & blocks
« Reply #2 on: March 24, 2008, 02:09:35 PM »
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What I do is run a separate bus for each detector section, then connect the track to that. This way, you can have all the expansions you need.

I read this to say, just like booster or power districts, What I do... (where the detectors have their own dedicated bus)?

Or did you mean that you actually hook the detection circuit to the sub-busses in all power districts and then I can have all the expansion gaps I need?
RICK

John

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Re: Occupancy Detection, signal systems, & blocks
« Reply #3 on: March 24, 2008, 03:27:58 PM »
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This is what I mean

http://www.loystoys.com/info/layout-wiring.html

basically, the block detector comes off the main bus, then the connections are made to the track. I run a third wire, connect the detector, then run feeders to the track from that .. hope this makes sense

cv_acr

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Re: Occupancy Detection, signal systems, & blocks
« Reply #4 on: March 24, 2008, 05:53:38 PM »
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2. My layout is in a basement that needs allocations for humidity changes (expansion
gaps) placed about every 10 feet. I certainly don't need a signal every ten feet for
the "block" I just created by gapping the track, so would it be correct to assume the
blocks needed for signaling would be defined by the secondary power bus and NOT
the track?

Attach a feeder to each section, and attach the sections you want part of one block to one main bus wire. Attach the end of the bus wire to a detector at your control panel.

My club is working on having everything wired properly for signal blocks & detection, and that's exactly how we do it. We actually attach one feeder to every piece of rail; we don't rely on rail joiners for electrical contact, just to keep the rails in line. It's more reliable this way. Each track section has it's own bus that all the individual feeder wires come off of to the rails.

Quote
3. The layout will have 6 primary power districts (booster areas). I don't know if this is
a proper question or not, but I wonder if the electronics involved for signaling bridge
these zones seamlessly or will a system be required dedicated to each power
district?

Pick block boundaries as the boundaries of the power districts. If you have any crossover between districts you'll have one big 30 amp district instead of 6 5 amp districts. Can you say "magic blue smoke"? At my club layout, the wiring originally wasn't done very well, and instead of 2 power districts, we had a single 10-amp circuit. We finally finished the massive re-wiring job that fixed that, and now we have two completely isolated sections, with a third booster that will power the new section that's starting construction. We'll probably have a couple more by the time the whole thing is done.
Each district is further subdivided with circuit breakers protecting the individual blocks, so a short circuit anywhere on the tracks won't affect any one else.
A far cry from before fixing the crappy wiring, where a short _anywhere_ would shut down the whole layout with cries of "ok, who the ..." The branchline still needs a lot of work to subdivide it into smaller sections with circuit breakers, right now the whole branch is a single block, but it's a step in the right direction so far.
« Last Edit: March 24, 2008, 06:04:52 PM by cv_acr »

SOUPAC

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Re: Occupancy Detection, signal systems, & blocks
« Reply #5 on: March 25, 2008, 04:04:00 AM »
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2. My layout is in a basement that needs allocations for humidity changes (expansion
gaps) placed about every 10 feet. I certainly don't need a signal every ten feet for
the "block" I just created by gapping the track, so would it be correct to assume the
blocks needed for signaling would be defined by the secondary power bus and NOT
the track?

Attach a feeder to each section, and attach the sections you want part of one block to one main bus wire. Attach the end of the bus wire to a detector at your control panel.

My club is working on having everything wired properly for signal blocks & detection, and that's exactly how we do it. We actually attach one feeder to every piece of rail; we don't rely on rail joiners for electrical contact, just to keep the rails in line. It's more reliable this way. Each track section has it's own bus that all the individual feeder wires come off of to the rails.

Quote
3. The layout will have 6 primary power districts (booster areas). I don't know if this is
a proper question or not, but I wonder if the electronics involved for signaling bridge
these zones seamlessly or will a system be required dedicated to each power
district?

Pick block boundaries as the boundaries of the power districts. If you have any crossover between districts you'll have one big 30 amp district instead of 6 5 amp districts. Can you say "magic blue smoke"? At my club layout, the wiring originally wasn't done very well, and instead of 2 power districts, we had a single 10-amp circuit. We finally finished the massive re-wiring job that fixed that, and now we have two completely isolated sections, with a third booster that will power the new section that's starting construction. We'll probably have a couple more by the time the whole thing is done.
Each district is further subdivided with circuit breakers protecting the individual blocks, so a short circuit anywhere on the tracks won't affect any one else.
A far cry from before fixing the crappy wiring, where a short _anywhere_ would shut down the whole layout with cries of "ok, who the ..." The branchline still needs a lot of work to subdivide it into smaller sections with circuit breakers, right now the whole branch is a single block, but it's a step in the right direction so far.

Chris, here's some more info on my layout and my intentions. Maybe this will help some...

Here's some more info...

My layout is an attempt to model the Southern Pacific Railroads Cascade Subdivision, which involves climbing over the Cascade Mountains in West-Central Oregon. From one end to the other it is climbing (or descending a railroad that is on a constant grade and very, very little tangent track.

My DCC system is EasyDCC. I went there after being totally fed up with Digitrax and I think its great. I still use Digitrax decoders, but that might change too.

My trackplan can be seen at

http://www.modelrailroadphotos.com/photos/showphoto.php?photo=849&ppuser=2993

My web site explaining the layout and progress can be viewed at...

http://www.spcascadesub.com

Because it is a single track line with 6 passing sidings, I can't see the need for a lot of detection blocks. In my simple mind, a block is dictated by the length of single track and 1 main/siding set. Sounds like 6 blocks to me. I have heard of "distant signals" which I believe the SP had, but I believe they only duplicated the next block signal, so I wouldn't think that would create any major issues, other than those dictating me to have to deal with electronics, that is.

If I don't have to learn some new language to program a computer, I can be okay with computer involvement. I already use DecoderPro and, while I'm not familiar with it, PanelPro would seem to be the obvious next step to at least give it a chance. I don't want to have to have a dispatcher in order to run trains.

I want the layout to be scenery oriented with the operations centered around a major helper district. My layout design does not indicate whether the layout is a PTP or LTL or continuous running. I'm thinking of altering the plan in that, instead of having the entire layout on one continuous grade, I might intercede (modelers license) and have it be an up and then back down the other side situation.
I want continuous running, but want to avoid a helix and a huge staging yard. I think maybe 2 staging yard tracks plus the main at the most. I'm seriously considering this depicting from Oakridge, OR to Dunsmuir, CA with a bunch of selective compression.

With ruling grades @ 2.5 %, I'm thinking average trains of about 40 cars and 8 to 10 engines.

If there are more questions that will help get me to the bottom of this, please ask.
« Last Edit: March 25, 2008, 04:05:45 AM by SOUPAC »
RICK

cv_acr

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Re: Occupancy Detection, signal systems, & blocks
« Reply #6 on: April 03, 2008, 06:26:18 PM »
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Because it is a single track line with 6 passing sidings, I can't see the need for a lot of detection blocks. In my simple mind, a block is dictated by the length of single track and 1 main/siding set. Sounds like 6 blocks to me. I have heard of "distant signals" which I believe the SP had, but I believe they only duplicated the next block signal, so I wouldn't think that would create any major issues, other than those dictating me to have to deal with electronics, that is.

Not quite, no.

You'll need a lot more than 6.

One block for (mainline track) alongside each siding (ie, between the two siding switches).
Obviously the siding is isolated from that, and if you want to see a train occupying the siding on the dispatcher panel, you'll need to detect that block too.
Also, keep in mind the special case right around the siding switch, between the controlling signals. That will have to be separately detected.

Minimum one block between sidings. On a model layout with rediculously short distances between sidings compared to the real thing, that might be all you can fit in. The distant/intermediate signals you mentioned would be at block boundaries between sidings. A real railroad could have at least 3 or 4 blocks between sidings, depending how far the sidings are apart (allowing trains in the same direction to follow each other between sidings).

For something really cool/scary, here's a schematic of where the planned block boundaries will be on the club layout I'm a part of:

http://www.wrmrc.ca/graphics/wrmrc_schematic-resize.gif

The thick lines are detected blocks, lighter lines are "dark" tracks just off the main tracks. Yard, branchline, industrial spur and other dark trackage not shown in detail (just the switches off the main signalled tracks.) Actual signal locations haven't been drawn on to the schematic yet.

Starting at the top left, follow the diagram as you would reading text on a page. Left to right, top to bottom. From the initial staging yard to the big wye junction at Romford is CTC. (With an automatic interlocking at the diamond at the "CN crossing" by Coniston. (This area was a sort of early primitive CTC, and the sidings were actually not detected on the prototype. The CTC there was actually later ripped out, and the line is now operated via radio clearances).

Romford is a manual interlocking, controlled by a tower operator (who in our case will be the same guy controlling the Toronto staging yard).

From Romford to Sudbury will be directional running with ABS block signals. (Each track is only signalled in one direction).

CTC starts again at the location marked "Nickel Sub. Junction" and covers the remainder of the displayed line.