Hi all, this is my first post on the forum so here goes!
Due to life circumstances, my layout building stopped dead in the water many years ago. Now, change of circumstance, pending total retirement, my enthusiasm has returned and I am on my way. I had a friend design a track plan to fit on my 14ft by 7ft layout. My original thought was to run trains with a dual cab setup but I am leaning very much to DCC. I still want to block my railroad though for C/MRI. I am attempting to follow Linn Westcott’s advice in his book “How to wire your Model Railroad” but am quite confused.
The easiest way is to first think of where your feeders need to go and where your gaps need to go to allow turnouts and reversing sections (if any) to work. You’ll see that your feeders tend to go at the common end of turnouts and the gaps at the diverging end. Each discrete section like that could be a block, but then you’re have a bazillion blocks even on a small layout. So next consider how to group those together.
For that, you should determine what track is the main, what is a siding and used in conjunction with the main, and what are spurs and yards used for sorting and holding cars. Group the electrical sections you identified according to that scheme and you should start seeing some natural combinations of these into blocks. Then look at what’s left and think again if it can go with any of the blocks you’ve already identified. Do that, if you can, or otherwise make them blocks.
Then apply to your project. As you build and wire, with each block completion, test it with power on and power off to all other blocks. The new block should be live and everythintg else NOT. If any adjacent section is to the new is live, you’ve left a sneak path between the two that needs a gap to truly isolate it. Do this consistently as you build and the testing will make sure you did things right.
That’s how I did my DC 2-cab wiring, intended from the get-go to convert to DCC. If you just need blocking for CMRI, etc, and will run only DCC you don’t need the hassle of two complete sets of wiring. You can get away with single-pole switches and cut your copper budget in half.
If you do intend to block for 2 or more cabs in DC, then in addition to everything I said above, go back over your plan and consider the various scenarios of how 2 or more trains running at the same time will get their power, because you have to be able to send the power to each loco as it navigates the main, pulls into sidings and swicthes yards while another loco is working nea
Short answer, for electrical, any rail that has a frog on one or both ends may need a gap (depends on types of switches you use), for operations/detection, any piece of track long enough to hold a “train” or a “control point” (place you want the signals to control access) needs gaps on the ends.
I guess it depends on exactly what you’re asking about…do you want to know about setting up blocks for running multiple engines/trains on DC, or setting up blocks for power districts / boosters for DCC, or setting up blocks for detection of track power to use in a working signal system? You mention C/MRI, which can refer to signalling or to running a layout by (or both) computer.
Keep in mind Westcott’s book was written a long time before DCC, and is just referring to DC layouts. In DC, all engines in a block will respond to power in the track, so you can’t have two trains in the same block and control them separately. In DCC, each engine can be controlled separately, so you don’t need ‘blocks’ to run multiple engines / trains individually.
You can wire a layout for DC and then covert it to DCC, it will still work fine that way. But if you’re building a layout just for DCC, you really only normally need a few ‘blocks’, like having an enginehouse wired separately so you can turn the tracks ‘off’ in the enginehouse, or a separate block for a programming track, or for a reverse loop (which in DCC you can automate). On a basement sized layout, you may want 3 or 4 ‘blocks’ so that each has it’s own power booster, boosting the power signal from the main controller.
Mike Lehman has it right. It all comes down to what is logical and practical for your layout. Think of it in terms of how you might operate the layout. If all you want to do is run trains (continuous running), then the separation of the layout electrically can be at a minimum. If you’re designing the layout for operations and that is your main intent, then you have to look at what will give you the most control and still not interfere with the operation of the other cab (throttle).
One thing I might add is that not every spur or siding needs to be isolated. If all you intend to do is spot cars at an industry or just store cars and not a loco, that switch or siding does not need to be isolated. It minimizes the “bajilloin blocks” scenario.
My general policy for creating electric blocks on a layout is:
On the mainline or branch lines every time you come to a turnout each fork is a new block.
For staging yards every time you come to a turnout each fork is a new block also.
For car sorting yards I don’t make a new block for each track because only the switcher is going to be working there. The yard lead might be a seperate block depending on design.
For engine or commuter train service facilities each parking space for an engine is a separate block. Blocks on a single track might be only the length of a single locomotive allowing you more control of which locomotives you can run or leave off. Same with commuter trains if you park more than one on a single track.
LION (That’s me, I’m a LION) likes INTERLOCKING PLANTS.
So after you have set up in your mind what your layout looks like and what your railroad is going to do for a living, the DRAW IT OUN IN A STRAIGHT LINE as if you were building an interlocking plant.
From that drawing, you can easily see where your gaps and such needs to be.
Elias I assume there is directional significance in the colored numbers and green and red circles. So I don’t get the wrong end of the stick, please explain for those similarly electrically challenged.
Blocking for control is a bit different than blocking for signalling. As I recall Linn Westcott’s book is for control.
For C/MRI - each segment of main line, passing siding, the turnouts on each passing siding, and any other turnout on the main need their own block. This is because the control system has to know if the turnout is blocking and if it can be changed or not.
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