Lower tier section complete

Minor milestone reached. As the picture below shows, the trackwork for the lower tier of the current section of staging is complete:


All the track shown has been wired and tested with a variety of locomotives (SD90MAC Kato, 2-8-0 Athearn, F3 Kato, SW1200 MicroTrains) that have proven in the past to be particularly sensitive to track problems. Of course, all testing has been with DC -- I should run some DCC over the switches to verify there are no shorts, but I don't expect any as these switches did not have shorting problems with the previous staging setup -- other problems, yes, but not shorting.

(Aside: DCC runs at a consistently higher voltage and amperage than DC, so DCC has built-in, fast-acting circuit breakers to protect the DCC and locomotive equipment in the case of shorts. One side effect of this is that momentary shorts which occur on switches aren't noticed on DC systems but can shut down a DCC system. This is why some more newly-designed switches have been labeled "DCC friendly", meaning less susceptible to shorting. For whatever reason I haven't experienced this problem running DCC on my layout.)

Two notes about the above construction:

1. The ideal order of construction on the staging area is upper tier (farthest from layout edge), middle tier, then lower tier. I will be following that order after I get past this section. However, at this juncture I should get the track down and tested on one tier before I construct the tier above it due to the planned bridges. Once a bridge is in place it will make access to the area underneath more difficult.
   
2. The biggest concern of mine vis-a-vis reliable operation in the staging area is the Atlas code 80 #6 switches. By using #6 switches, instead of the smaller and more standard #4s, the likelihood of reliable operation should go up because the switch curves are less sharp and abrupt, thus less stress is placed on the moving trains.
   
   Even so, on the first staging attempt I experienced fairly frequent derailments with these switches. By luck, I recently bought a stack of 1980s Model Railroader issues very cheap from the back of an antique store and discovered an article from 1985 on making your Atlas N scale switches bulletproof. The article was about the #4 switches (for all I know they didn't have #6 switches then), but I followed it closely and got many good pointers. One thing I learned is that Atlas has improved their switches many times over the years. A number of problems the author mentioned in design aren't present anymore. Still, he provided a good methodology for testing both the switches and the switch machines, and some instructions for improving reliablity. These boiled down mostly to filing the tips of the points and of the frog if the switches showed signs of catching the wheels. This was a useful article and I now run every new switch through this standard set of tests and adjustments before putting it on the layout.
   
   Yet, the article didn't address the two biggest concerns I had going in. The first, from what I could diagnose from the first staging attempt, was that the top of the rails were uneven when the switches were connected in a ladder. This is apparently because when I glued the switches to the roadbed I used pins to hold them down, as I normally did for all track back then. But the switches have smaller pin holes in the ties than the flex track does, so this caused the pins to push the ends of the switches down harder into the roadbed while leaving center of the switches not so deep in the roadbed -- in effect causing the switches, when viewed from the side, to to have a convex shape. Put them next to each other and the rails went down-up-down-joint-down-up-down-repeat, and no wonder derailments were common as model trains don't do vertical curves well. This time around I'm still gluing the switches on the roadbed (of course being careful not to glue the area near the moving points and throwbar) but using flat weights to hold the whole switch in place, not pins. So far this has successfully kept the rails level from switch to switch and, at least up until now, elminated the derailments.
   
   There is one other problem that concerns me, although it's not yet caused operational issues that I can detect. The straight rails on the switch aren't really straight, but instead tend to bow slightly in the direction opposite the diverging route. This is so slight that it won't be a problem for an isolated switch, as the adjoining flex track can make up for the slight curve. However, in a switch ladder this causes the train to go through a slight left-to-right movement while going down the straight tracks on the ladder. So far this is just something to watch, but I do wish Atlas would fix their #6 switch manufacturing to correct this curve. Alas, I bought all the code 80 switches I thought I'd need for this layout a couple years ago, so even if Atlas does correct it I'm stuck with what I have.

My final comment is that these posts are now almost current with the state of the railroad construction. The above picture is from yesterday. I did get a little bit done on on the layout today, and I hope to post on that tomorrow.