I am getting to a point soon where I am going to start installing the bus wires under my N Scale layout so I can connect the track to a DCC system (or maybe a basic power supply in the beginning). I am wondering what ideas you folks might have for connecting my yard to the bus. The yard is about 50 feet long, with 8 double-ended receiving tracks and then 21 classification tracks. There is an additional small yard on each end of this complex, one for loading/unloading autos and the other an interchange yard with the local shortline. The double track main runs along the back side of the yard. Do I need to run a separate bus for the yard, branching it off the main bus, or should I plan on just running the bus in the middle of the benchwork and run the jumpers to that one pair of wires? Thanks for any advice!
If you are using circuit breakers to split up your layout into sub-sections (a good idea), I would put the main line and the yard on separate breakers, and therefore, separate busses. Then, if a yard crew runs through a switch lined against it, the main line won't shut down. On a yard this size, it might be a good idea to break up the yard as well.
Thus is similar to what I had to do with my yard. There was a detailed method to calculate this on the the DCC Wiring Sticky that disappeared, but I will try to recreate it here. Really Large Yard - Well this is where we may have stepped beyond reality for most folks. As a design exercise, I got a plot map of the ATSF yard in Barstow CA. It had split diamond with a dual mains down the center and several drill tracks and arrival departure tracks on both sides of the mains. There was a turntable and all sorts of maintenance buildings etc. There was even a passenger terminal cutout from the mains. In N scale, the yard would scale out to twenty two feet wide by seventy three feet long. This is a multi power district situation. How many power districts do you think are needed? Let’s use the Barstow yard analysis as an example: Here are the steps: 1. Look for natural physical separations. 2. Look for isolated track areas and the type of traffic on those tracks. 3. Look at the local complexity of the track work. 4. Look at the relative length of track. 5. Look at the rolling stock length and wheel sets of cars that will be cut. 6. Think about operations of the tracks. 7. Think about the power calculations we made above. When we have examined all the aspects of the yard operations. We can start with the power district design. Here is my design: 1. Passenger terminal cutout is isolated from the rest of the yard. It comes off the main and returns to the main. Because of terminal tracks and lighting effects in passenger cars, I would opt for this as a candidate for a power district. 2. The double main lines and their associated arrival and departure tracks would constitute another candidate for a power district. In this case, similar to the passenger terminal, I have a way of isolating the operations of the mains from the rest of the yard, and I include the arrival and departure tracks here because they can also act as the termination point for the main line train. 3. The Turntable area on the southern side of the yard is also a power district, not just because of the reversing section needed, but also because of the amount of complicated track associated with the engine house and the service tracks in the steam shops area. 4. The diesel and car servicing area on the northern side of the yard has more track associated with it and some complicated track work as well. 5. The east side classification tracks on the north side of the mains because there is yet more complicated track and a lot of track in the 42 classification tracks. 6. The west side of the classification tracks on the north side of the mains because there is still a lot of track. 7. The east side classification tracks on the south side of the mains because there is yet more complicated track and a lot of track in the 38 classification tracks. 8. The west side of the classification tracks on the south side of the mains because there is still a lot of track. So far that is 8 power districts, and we may not yet be finished. It may be necessary to split the classification yards into 4 power districts each because of power use or locomotive operations, rolling stock power consumption or wire losses. Another example is if I have a lot of cabooses on the caboose tracks with lighting decoders and internal illumination. That could add to the power consumption. So we now need to go back and list our power sources and uses to see if this design makes sense. In my final design, there are 16 power districts based on the discussion above, plus a few extra for operational safety. I split the north and south classification yards into 8 power districts due to size and such. The others stand pretty much the way illustrated above. Does this mean I need to have 16 power boosters to run the yard? No, I do not. The reason is the bulk of the track is rolling stock with very little power consumption. I split the classification tracks up not for power uses, but for operational uses against a switcher derailing or a metal wheel picking a turnout point and shutting down the whole section of the yard. In my solution, only a quarter of the classification tracks on either side of the mains will shut down. So how do set it up and how many boosters will be needed? Because of the lengths involved, and the operational usage patterns, here is how I would implement the power districts. 1. Booster 1 - using two circuit breakers for isolating the passenger terminal from the main lines, I can power both of these from the same booster. The reason is that most of the time there is only one train in either track section because the trains are out running on the layout more than they are parked in the yard. 2. Booster 2 - using a dedicated booster for the steam servicing area. The reason being is that I am designing in case all of the steam locomotives have sound decoders installed. Plus there is the Turntable and other track elements and the fact the steam locomotives will find every flaw in the track work. The power consumption calculation for steam operations drive the need for a dedicated booster. 3. Booster 3 - similarly, I have a dedicated booster for the diesel servicing area as well. This is mostly power driven since I will park all the diesel locomotives here that will be used on the layout. That is a lot of ABBA EMD F units in my modeling era. 4. Booster 4 - north side classification yard. The booster is shared by all eight power districts using electronic circuit breakers. Again the reason is more operational here than power consumption. A couple of switchers will not use that much power, so this is a guard against derails in operations shutting down the whole yard area. 5. Booster 5 - south side classification yard following the same implementation of the north side classification yard. By looking at both the power consumption, and the operations of the Barstow yard, we have covered all 16 power districts using only 5 boosters, and taking advantage of electronic circuit breakers instead of boosters. This is how I setup my implementation of the ATSF Barstow Yard which is scaled pretty close to the actual dimensions in N scale. Hope this helps!
Hmmm. Then I can see needing, separate from the main, 3, maybe 4 power districts for the yard. I'm completely green with this DCC stuff, so it's gonna be a steep learning curve for me. I am going to have 2 staging yards, each having about 12 tracks, so I'm guessing I will need a power district for each of those also.
Given where you are on the learning curve, one approach might be to block the layout similar to the way you would for DC operation. You can then connect "blocks" under the benchwork into power districts, making changes as you gain knowledge and experience. If you want to add signalling at some point, you can then use these blocks and avoid having to cut more gaps. Doug Stuard
