# Designing Block Detection



## Greencardude (Jun 6, 2016)

Ok . . . second post tonight, but I'm at a critical step in my layout and I just love how much knowledge there is in this forum.

Does anyone have any guidance on the why and how and where for segmenting track for block detection? This is a freeform type question and I was just hoping to pull on the collective knowledge, especially given how little I have.

I've attached a link to my trackplan:

http://www.timbratcher.com/MODEL_TRAIN/DONE-001.jpg

You can see how I've broken it up, but just trying to get the most out of DCC / the BDL168s, so I was just looking for thoughts, guidance, experience, hindsights, and so on!

Best,

Tim


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## D&J Railroad (Oct 4, 2013)

I would have to study this diagram for a while to decide where to put the blocks. Basically, your blocks should support where you want to put signals. 
Keep in mind, each of your turnouts will require three, three aspect signals. Consider how an engineer approaching a turnout from any direction, what he would need to see so he doesn't run over a thrown turnout. The same with a series of blocks of track. If you want to work with three aspect signals, i.e. red, yellow and green, you will need to lay out what the signal will be providing information for. A single three aspect signal can provide information for two blocks ahead of the train as well as turnouts that are directly ahead as well. A stop signal is a stop signal regardless if it for an oncoming train or a thrown turnout.


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## johnfl68 (Feb 1, 2015)

Model Railroad Blocks can be somewhat subjective, and often times it boils down to what YOU want to do with the blocks. But there are lots of good suggestions out there.

The suggestion that I have seen a lot around in searching is keep the blocks as long as your longest consist of engines and cars.

In reality, that doesn't always work. But you need to keep this in mind when it comes time to program automation. If your consist is more than 1 block long, you want to make sure you add an extra buffer zone of clearance behind the train along your mainline, to keep the next train from entering a block that the tail end of the train in front may be still in.

Just be careful when first starting out with your automation, to make sure it is behaving as you expect. Don't always expect it to keep trains from colliding with each other.


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## Greencardude (Jun 6, 2016)

Just based on this feedback, I think I have entirely too many!


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## JerryH (Nov 18, 2012)

On a compact layout with automation actually running one or more trains, lots of blocks helps the keep things moving. You might want take a look at this thread.

http://www.modeltrainforum.com/showthread.php?t=14852


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## gregc (Apr 25, 2015)

Greencardude said:


> looking for thoughts, guidance, experience, hindsights, and so on!


in general, a block should extend from the trailing end(s) (not the points end) of a turnout to the trailing end of a turnout.

It may make sense to split a long block if there are train movements that occupy part of a block when switching between the blocks across a common turnout.

Here are some examples: 

A15 should not include any part of the turnout. That turnout should be be entirely part of A19. And A15, A14 and A13 combined into a single block.

From a detection point of view, by including the turnout part of A15, a locomotive moving between A19 and A18 would also be detected on A15 while crossing the turnout. By making the turnout part of block A19, a train crossing the turnout would be properly detected on block A19 whether moving into block A15 or A18.

similarly, block D1 may not need to separate from the yard since it is the yard lead, part of the yard.

A12 is probably unnecessary, split it between the two turnouts.

From a detection point of view, the turnouts within B8 can probably be left "dark" while B8, B7 and B6 without the turnouts, can be combined into a single block.

The turnouts in C8 and B6 should be part of B5.

B3 and A3 are unnecessary

i'm sure that are other simplifications


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## fcwilt (Sep 27, 2013)

Hi,

What software are you going to be using?

Have you already bought your BDL168 units?

Frederick


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## Mark VerMurlen (Aug 15, 2015)

I agree with gregc and his comments. I think you've got far more detection blocks than you really need. I would condense several of these consecutive small blocks into larger single blocks. The only time you may not want to do this is if you want to have high precision stopping points. I would condense B12, B1, and B2 into one block, however if you want to have a couple of higher precision stopping points within this block for industry or passenger stations like I see in your drawing, then I could see keeping that track more segmented in that area.

I think the biggest mistake that you need to fix in your layout is to get the turnouts in the right block. As gregc mentioned, you need to change several of yours so that the turnout is part of the block on the facing points side. 

One thing I don't think gregg mentioned, is how to handle the 3 turnouts that are back to back starting with B10. I have a few of these situations on my layout too. I decided to make the series of turnouts all part of one block. The whole purpose of doing block occupancy detection is to be able to control access so that no more than 1 train tries to occupy 1 block. So in the case of several interconnected turnouts, you only want 1 train in that whole section and thus making them 1 block will assure that. That's the general logic that I've used throughout my layout to section it.

I decided to go with TrainController for my automated control software. It has the ability to combine multiple occupancy detectors into 1 logical block, so if you do decide to keep lots of small detection blocks, you can condense them down to a smaller number of logical blocks in the software.

Hope that helps.

Mark


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## fcwilt (Sep 27, 2013)

Mark VerMurlen said:


> I decided to go with TrainController for my automated control


Well now I'm a little confused. 

Herr Freiwald states that turnouts should not be part of a block.

Your response includes advice to include them.

Why did you not follow the advice from Herr Freiwald?

Frederick


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## fcwilt (Sep 27, 2013)

The block size depends in part on the software.

I use TrainController (TC).

Each train in TC needs at a minimum two blocks - one to be in and one to enter.

If your blocks are very long then it will take a longer amount of time before a given train clears the block it is exiting allowing any following train to move up.

So let's use some extremes here.

If you had 100 foot blocks then 100 feet of track would be "held hostage" by a train as long as any part of the train was in the block.

On the other hand if you had 2 foot blocks as the train progressed the blocks behind it would be released 2 feet at a time rather than 100 feet at a time.

YMMV

Frederick


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## Mark VerMurlen (Aug 15, 2015)

fcwilt said:


> Herr Freiwald states that turnouts should not be part of a block.
> 
> Your response includes advice to include them.
> 
> ...


This boils down to the fact that most of the time, you only want 1 train in a block at at time. If the turnout isn't detected, how can you really be sure that there isn't a train within it or overhanging it? I think in reality, the software is written such that it gives plenty of margin for error and it really won't matter much. In my case, I've got resistors across the 2 end axels of all my rolling stock, so I can absolutely detect when a train is within or passes out of a block, including the turnout. Besides, powering every turnout separately from the blocks around it is a major pain in the backside.

Mark


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## Mark VerMurlen (Aug 15, 2015)

fcwilt said:


> The block size depends in part on the software.
> 
> I use TrainController (TC).
> 
> ...


Yep, you need to pick a happy medium between too many and too few detection blocks. 

Mark


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## fcwilt (Sep 27, 2013)

Mark VerMurlen said:


> This boils down to the fact that most of the time, you only want 1 train in a block at at time. If the turnout isn't detected, how can you really be sure that there isn't a train within it or overhanging it? I think in reality, the software is written such that it gives plenty of margin for error and it really won't matter much. In my case, I've got resistors across the 2 end axels of all my rolling stock, so I can absolutely detect when a train is within or passes out of a block, including the turnout. Besides, powering every turnout separately from the blocks around it is a major pain in the backside.
> 
> Mark


I went ahead and installed separate occupancy detectors for turnouts and turnout groups.

Yes it was more work but I can be sure if a train has overrun the end of a block.

Very glad I did.

Frederick


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## Mark VerMurlen (Aug 15, 2015)

fcwilt said:


> I went ahead and installed separate occupancy detectors for turnouts and turnout groups.
> 
> Yes it was more work but I can be sure if a train has overrun the end of a block.
> 
> ...


I'm curious then about how you assigned the detected turnout blocks to the logical blocks in TrainController? I'm not being a wise-guy here, I'm interested in your logic and and how well it has worked for you in reality. I'm hoping I can learn something from your approach.

Mark


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## D&J Railroad (Oct 4, 2013)

Mark VerMurlen said:


> I'm curious then about how you assigned the detected turnout blocks to the logical blocks in TrainController? I'm not being a wise-guy here, I'm interested in your logic and and how well it has worked for you in reality. I'm hoping I can learn something from your approach.
> 
> Mark


I'm using TC Silver too and it's just a matter of identifying the block you want your signal to respond to. It really doesn't matter were the block is or what you name it. If you tell TCS to set a signal to red when a certain block is occupied, it does it. It's all just computer addresses.


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## fcwilt (Sep 27, 2013)

Mark VerMurlen said:


> I'm curious then about how you assigned the detected turnout blocks to the logical blocks in TrainController? I'm not being a wise-guy here, I'm interested in your logic and and how well it has worked for you in reality. I'm hoping I can learn something from your approach.
> 
> Mark


TC allows assigning a Contact Indicator to a Turnout.

The Turnout Occupied State is determined by the state of the Contact Indicator.

All Routes containing this Turnout inherit their Occupied state from the Turnout Occupied State.

The Turnouts are NOT part of any Blocks. They are parts of Routes only.

Routes, of course, are the paths from one Block to another Block as determined by TC.

Since TC can now know when Routes are Occupied (not just Blocks) it can make better decisions such as not throwing turnouts under trains.

I have also used the Condition tab of the Turnouts to prevent me from manually throwing turnouts that are occupied.

Frederick


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## Mark VerMurlen (Aug 15, 2015)

fcwilt said:


> TC allows assigning a Contact Indicator to a Turnout.
> 
> The Turnout Occupied State is determined by the state of the Contact Indicator.
> 
> ...


Thanks for the explanation. This helps a lot. Is the ability to assign a CI to a turnout only in the Gold version? I don't see it in my Silver version. Maybe I'm not looking in the right place. 

I'm about half way done laying my track and I've been wiring up the detection blocks and turnout motors as I go. I've also got my layout fully entered into TC's switchboard view. However, I haven't been able to fully play with all the automation capabilities yet since not all the track is laid.

Making a separate detection block for every turnout will be quite a chore and expand the hardware I need significantly. I can certainly see the value in not allowing the turnout to change state while occupied. How TC prevents that was one of the things I wasn't able to understand in my reading of the manual. My guess is that TC has a lot of delay in changing turnout states after a train passes by just because most people don't detect them. I'll have to make a decision for myself on if this is important enough to me to spend the money and time to do it.

Again, thanks for the explanation.

Mark


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## fcwilt (Sep 27, 2013)

I just checked and yes it is a GOLD feature - keep forgetting about SILVER and BRONZE.


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## Greencardude (Jun 6, 2016)

Mark and Frederick, thank you so much for the insight. I've written about a dozen responses to hone in on a few things, but each time I consider what you've said, I have to start over. You've given me a lot to think about, and as soon as I can digest it, I will come back to maybe ask you guys some questions and maybe post an updated / simplified track plan, reflecting your input.

Here's one for you now, though: 

--Can a given subdistrict output from a PM42 feed to an AR1 (Digitrax auto reversing unit), and then have that AR1 feed into those zones of a BDL168 used for block detection inside the reversing area?

--It seems as though this is contemplated on p. 18 of the BDL168 manual on Digitrax's website: 

http://www.digitrax.com/static/apps...gnaling/bdl168/documents/BDL168_flattened.pdf

If that were the case, then I could split the C subdistrict from my PM42, send one prong to the engine servicing area (C7 to C??) and then the other prong to the AR1, which, in turn, feeds, for example, zones A and B on the BDL168, to give me 8 detection blocks in the reversing area (C1 to C6).

I'm probably stretching the limits of good sense, but it seems to make sense to me.

I've had about 12 hours of sleep since Tuesday morning . . . trying to close several financing transactions and it's killing me. I find myself running through all of this stuff in my head, when I'm on long, boring conference calls! 

Again, you've given me a lot to think about, so let me digest it and come back.

Thanks again, everyone!

Best,

Tim


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## fcwilt (Sep 27, 2013)

Hi Tim,

Have you purchased any of your electronics yet?

I ask because I would never suggest anyone to use, for example, a BDL168.

Frederick


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## fcwilt (Sep 27, 2013)

Hi Tim,

I cannot speak to the BDL168 since I sold all mine before starting my layout.

With the products I use yes it is possible to put the occupancy detection AFTER the auto-reverse unit.

Frederick


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## Greencardude (Jun 6, 2016)

I have purchased a DCS200, a couple of AR1s, 1 BDL168, a PM42, and a PR3. 

Would be interested in hearing your thoughts, though, Frederick.


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## fcwilt (Sep 27, 2013)

Greencardude said:


> I have purchased a DCS200, a couple of AR1s, 1 BDL168, a PM42, and a PR3.
> 
> Would be interested in hearing your thoughts, though, Frederick.


I would STRONGLY suggest you consider products from here:

http://www.rr-cirkits.com/index.html

The web site is nothing to write home about but the products are first rate.

The designs are state of the art, the products are easy to install and the customer support is top notch.

The products of interest for your are the Simple Serial Bus (SSB) items.

They are LocoNet compatible.

They work with Train Controller.

They can be configured using JMRI DecoderPro.

The SSB line includes the:
- WatchMan (occupancy detection)
- MotorMan (turnout control)
- SignalMan (signal control)
- TowerMan (general input/output needs)


The WatchMan has a very significant advantage over the BDL168. 

The WatchMan uses small coils to detect current flow in a block. You slip a coil over one feeder wire to each block. 

The coils connect to the WatchMan using a pair of wires - I use twisted pairs extracted from CATx cable.

This approach means the block DCC power wiring and the occupancy wiring are completely separate.

The WatchMan is also a good value at $7 per block.

The detection sensitivity of the WatchMan is set using DecoderPro on a block-by-block basis.


All of the SSB boards are based on the same underlying design. They all are the same size at about 1.5" by 3.5". Connections are all screw terminals, compression or flat cable.

RR-CirKits also makes a number of "I/O" modules that are compatible with the I/O ports on each SSB device.


You may also wish to consider these for DCC power management:

http://www.dccspecialties.com/products/powershield_x.htm

They are all solid state - no relays. 

The circuit breaks are individual devices that can be placed on the layout as you desire to optimize the wiring.

No edge connectors - all screw terminals.

Current levels and timing are configurable.


I highly recommend the products both from an end users point of view and from my professional point of view as digital circuit designer for many yeas (now retired).

I have no financial connections with the companies in any way.

Please do not hesitate to ask any questions.

Frederick


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