OK, So I'm working on breaking up a friend's layout into blocks and creating a schematic and wiring diagram. I could use a lot of feedback on this, as I'm not actually all that experienced at designing blocks operationally. The design is single-cab, only one train running, under DC control.My friend is pretty adamant about not running more than one train, thinking that IF he ever changes his mind, he'll go DCC. Despite that, I want to go ahead and design with block control and dual cabs, as an educational experience for myself and others. So, here's the layout drawing: And here's Version 1 of my track schematic: This may be a bit overdone, but here's basically what I've done: Split both mainline loops into left and right halves. Put the Sector plate approach tracks on their own, combined block. The bridge is tied electrically to both tracks, but can be turned off. The warehouse, mill and museum are on a separate block The passenger station and engine service area are on a separate block. 7 blocks total, not counting the sector plate bridge itself. Additional notes: Each individual stub (passenger, engine service, warehouse, mill and museum) has a separate on/off power control. Wiring is 2-wire isolated blocks. Questions I have: Did I introduce any reverse loops? Do I really need the left/right split of the mainline? The outer loop in its entirety is 13 feet. I put the sector plate approach tracks on their own block so that you could pull a loco off the plate and make it wait for a passing train on the outer main. Good/bad/indifferent? What else did I miss? Once I've got the block diagram decided upon, I'l translate that into a wiring diagram and a simplified version for single-cab and/or DCC control. Thanks in advance for your help!
< crickets > Hellooo?? Anybody home?? Version two of the schematic. I've numbered the blocks and added letters for block boundaries, so I could talk a bit about operational "whys". Starting in the lower left corner. Boundary A/B (blue/orange/green) beyond the switch so that a blue train can stop short at A while a train crosses boundary B from inner to outer loops. Likewise, a Green train can stop short of the crossover at B to wait for a Blue train to pass into Orange (through A) before crossing. Boundaries H and I (sector plate).See below for an explanation. The physical locations of H and I can be anywhere along the orange and blue blocks you want (short of the switches at A and C). Boundaries D and F. In place so trains can stop short while a train exits the spur onto the inner loop main. E is in the wrong place. It should mark the boundary between teal and purple, just like G marks the red/green boundary. Both simply show that a train can hold on the spur while another passes on the main. So you see that, operationally, only H and I are flexible in their placement. All the other block boundaries are constrained by where you need to have trains stop in order to allow others to pass. Hiding trains in the tunnel: As drawn in the first attached schematic, you can still hide trains in the tunnel by turning off the orange or teal blocks. However, this will prevent trains from passing points A or H on the outer loop, or (effectively) from exiting the station at D/E. That's probably a bad thing. Fixing this requires another block explicitly bounded at the tunnel portals on the inner loop. That way, one can park a train in the tunnel, but the open track between the switch at D/E and the tunnel can be used as a lead track for the station and possibly allow a short enough train to zig-zag from the station to the outer loop (by way of the crossover at C) while a train is parked in the inner loop tunnel. The second schematic shows this fix. I could have just jumped to that one, but I wanted to illustrate the thought process. The matching dark orange block on the outer loop (L -> M) is probably superfluous, but the dark blue block on the inner loop will preserve significant operations. Sector Plate Operations: The normal operation for using the sector plate would be to run in on one track (say, at H), switch over and exit at I, then run back around the outer main from I to H. Or vice versa. Having the turnouts at H and I on separate blocks just means you've got to tie up a bunch of blocks and flip a lot of switches. By putting the whole sector plate, plus the mainline curve from H to I on one block means you can stop a train short at H or I while a loco (not necessarily the stopped train's loco) performs the whole reversal movement, and then resume operation on the main. HOWEVER, what you can't do (without a further modification) is stop a loco inside the sector plate area while trains pass on the main. The fix for this is to put the two approach tracks on the same "kill switch" as the bridge itself. That way you can run a loco off the bridge up to just shy of the turnout, then turn off the track while the main is still powered. I decided not to burn another line color to show this. Mostly because I'm running out of visually distinct colors. This still doesn't create an electrical reverse loop because the sector plate bridge never completes the loop. As an added bonus, putting the whole sector plate on one block neatly solves the problem of making sure the block directions (in DCC) are set correctly. Please comment and discuss. I want to make sure this is correct before moving on to wiring. Thanks!!
Okay, I'll offer some advice... Think about operations. As a very general rule, you need to place boundaries for blocks (or power-off sections) in places where one train would need to stop to allow another train space. Not all of your boundaries you've proposed follow this principle. To begin with the obvious, you have two loops that could have different trains on them. So separate the loops in the middle of the crossovers. Next, you have two switching areas on the inside loop. Conceivably, you could have two trains switching each of them at the same time. Since they are on the 'top' and 'bottom' of the loop, that argues for dividing the inside loop into top and bottom blocks that include the switch areas. You could probably justify another block or two on the inside loop area, but I'll leave that to your imagination. Another important thing is that you may want to have trains on the inside and outside loops trade places. To do this, you need to have the outside loop split between the two crossovers, as you've done at point A. Obviously the loop needs to also split somewhere else to create two separate blocks. The logical place for this might be between the two turnouts going to the sector plate. That way a loco can travel to the sector plate even if there is a train in the other half of the loop. The sector plate, and it's approach tracks if you like, (but not any part of the main) are their own reversing block. For the life of me, I cannot understand why you think you need a single block between H and I. From an operational point of view, a train has no business traveling in the general direction of that area if there is a second train occupying that territory. It makes more sense to have a boundary between the two turnouts as I mentioned. Finally, you have some sections (not separate blocks), such as industry spurs and tunnels, that you will want to turn OFF to park locomotives, a concept I see you are already familiar with. In the switching areas these sections can be placed various ways according to your preference.
Ben, Thanks!! Yours is the first substantial critique I've gotten, and I appreciate it. Now that I go back and think it through, you're right. I have the sector plate use case exactly backwards. I put it all in one block thinking the loco would enter at I, use the sector plate, pull out to H and then go back along the curve to I. But he would *never* do that, because that would reverse the loco twice, which would be a useless operation. Unless the loco happens to be a dog getting ready to lay down. I had it right the first time, with the Blue and Orange blocks splitting in between the turnouts to the sector plate. Going down through your advice point by point, to see if I've got it: Split the two loops from each other at the crossovers. Got it - at A and C. Including the switch areas in the inner loop segments. I kindof mis-used my color scheme here. I do intend for the operator to use the Green/Red blocks together to service the top, and the purple/teal blocks together for the bottom. I colored the red and purple sections separately to indicate they are turn-off areas where he can stop a train on the spur to let another train have the whole loop. So the way I'll probably wire them is that the pairs of "blocks" as shown will really be the same block, but the spurs will be turn-off areas, not fully powered blocks. Allowing trains to trade places: Sounds like if I correct the error on the sector plate, I'll have this, with the outer loop split into orange and blue halves at A and between the sector plate turnouts. Power-off segments are not shown, but will be included in various places. What's your opinion on having the dark-orange block in the tunnel on the outer loop, vs. just having the whole area from A to H (or, rather, between the SP turnouts) be one big block. The layout owner wants to be able to park trains in the tunnel, but I'm not sure how useful it is to have the sections from A to L and M to H be "live" while a train is parked in L-M. Clearly having the "tunnel block" on the inner loop is necessary, or you can't use the segment E-J as a lead for the passenger/service spur. Again, thanks for the advice. I will revise and repost after a bit. Anything else?
Updated schematic. Little red bars indicate cut points - track beyond that point can be powered off with a switch. Pairs of LRB's connected by dotted lines indicate track segments controlled by a common switch. I left the industry spur on a block because it's conceivable (though not likely) that a switcher - or the museum engine - might be operating there while the inner main is occupied. Hopefully this fixes the sector plate problem, too. I also noticed an operational problem with the warehouse stub. It's facing point. I'll need to talk to the owner about how he wants to address that.
My 2 cents: The sector plate, and anything wired to it, are a reversing block. Whichever polarity you use for the connections, you will find it does not match one or the other leg where it connects to the rest of the layout. You need to allow for this area to reverse polarity. For that reason, and to allow storage without adding a bunch of on-off switches, I'd consider making it its own block isolated from the main. Here is my take on the blocking. I think it is all pretty obvious and mostly covered above. Below I'll add my thoughts on two specific areas labeled in my image. First for the part marked "reversing lead", that term isn't meant to indicate an ELECTRICAL need. Rather, operationally, it would allow you to bring a locomotive out of the transfer area to the LEFT/West direction, and still send it clockwise, without taking up the whole block in yellow. If you wanted to allow that you should take the area inside this box, out to a loco length or more, and make it into its own block. I did NOT mark it as a block. The box marked "switching lead" means that it is possible you'll be using some part of the main here to switch the industries. The switching loco will need to occupy part of this track with cars, and probably its own self to deal with those cars. You can either push the green block west/left to make allowance, or simply require that the swithcing job "own" the whole main back to the station area while working. However if you do that, you have nowhere to park a train on the inner main while the switch job runs. So, if you want a train parked at the station, and room to switch the industries, you'll need to have the green block pushed west OR make the area inside the box its own block. If you were to add any on-off switches, consider the engine track inside the engine-passenger facility. You can of course add more blocks and get more places to park trains. I think you'll create more chances for error without adding much operation, though. I'm not saying I didn't overlook a block or two, but rather that as the poster above said the blocks can be viewed operationally as well as electrically, and operations don't require breaking the main into as many pieces as some of your versions indicated. Good luck! I think you're very smart to do this exercise on a smaller layout.
Of course as soon as I post ... heh. One issue about my simpler arrangement is that there is pretty much no way to deliver a car to the Warehouse lead without either (a) running a switch job the opposite way or (b) using the crossovers at the station for a runaround. Which, in my wiring, would mean owning ALL OF BOTH MAINS. So I guess you do either need more blocks, or you need to reconsider the operations of that facing-point turnout that leads to the warehouse.
PJC, Thanks for the feedback. I see your point about the green track needing some additional ownership across the top to switch cars into the mill spur. I can move that block boundary back easily. As for the sector plate, the way it's designed, it gets its power from whichever of the two tracks it's pointed at. When it's swinging, it's dead. So, electrically, it should look like two separate spurs, not like a reverse loop. That's why I originally set it up so the approaches were tied to the outer main blocks. I haven't posted it here, but I've also put those tracks on an on/off switch, so the whole area is dead if desired. That way, the operator can park a locomotive on the approach track, kill the power, and still run trains on the outer loop (I believe he intends to only visit the sector plate "light"). I see the Warehouse lead problem, too. I'm checking with the operator to see if he wants to run this with an opposite-direction turn, or whether we should add a runaround on the inner loop, topside. On the "reversing lead" ... I'm not sure why that's needed. The purpose of the sector plate itself is to reverse a locomotive (or a short switcher and single car). If a loco enters at I, swings on the bridge, then exits at H, it will only want to continue counter-clockwise. If it goes back clockwise, it will have undone the reversing operation, and might have just as well exited the sector plate at I. If it enters at H, the only reason it would leave at H is if it changes its mind and wants to go back counter-clockwise. Am I missing something? Oh, and here's the latest update on the schematic. I haven't extended the green block yet, but I will. Red cross-marks indicate boundaries of power-off segments. Cross-marks tied with a dotted red line delimit paired boundaries. If that makes any sense.
Aha, I get how you've wired the sector plate. Clever, because it does solve the reversing problem and it also keeps the track dead while it is pointing at limbo. Very nice. On the "reversing lead": if a locomotive enters at I, turns, and exits towards M, you'd want a block for it to occupy that doesn't go all the way around to the station. Your diagram does this, and the section from the sector turnout west to M is effectively that lead. Even running light you need a loco-lenght of track for that. If your operating rules mean all locos enter FROM M and exit towards I, then this isn't an issue. I think your revised design will do fine. It would be possible, but a real puzzle (in the fun sense), to try and get three trains doing something operational in such a small space, and I think you can do it. About the only operation I can see that will need another block added to your diagram is, a train on the outer main can't use the crossover to the inner main without owning all of the green block, back to the industrial area. If you anticipate doing that you might want to add a block boundary just east of the points on the INNER main. Then you can run from the outer main into the passenger area, back in, drop the cars, and get all the way back to the outer main without stopping a switch job at the north industries.
Also I think I understand your reversing section plate question better. Yes, you need to exit on the opposite arm you entered. But there is no requirement that you then CONTINUE that direction. It depends where you are going next. Even though the track is a loop, there may be cars in the way, even the train you're intending to pull. But if the rule is "always clockwise" then that's a good, safe, and simplifying operational rule that will sometimes cause you puzzling (fun) problems. Very prototypical! Except they never call them fun on the big trains.
OK, for better or worse, here's where we ended up. Each different color represents a separate block, except... The user is pretty adamant about running this single-cab, not dual. So to accomodate that, I gave the option of combining the light and dark blue segments on the outer loop, and the light/dark green shades on the inner loop to reduce the total number of blocks. I've tried to address all the issues brought up here, and I hope I corrected at least the major problems! I think this will accommodate his operation needs. Final comments?? Thanks for your help!!
I guess this is a silly question but if he is insistent on only running one train at a time, why do you need blocks? The whole purpose of blocks is to permit two trains to operate. Set up the sector plate to be self reversing depending on which way its lined and put one gap in one rail of the service track so you can park an engine, install one SPST switch to that rail and you are done.
