The Turning Point Part 3: Rocky, the Big 10 and Clay

To complete the design of the Layout Design Complex (LDC) that is formed by the layout design elements of the exit from Barbara Gulch under the US-36 bridge, the siding and junction of Rocky, the Big 10 Curves, and finally the siding of Clay, there needs to be an analysis of the grades to determine if they are effective in providing the transition between layout decks. To read the previous entries about the LDC (Part 1) and the design of the LDC (Part 2) see those blog entries.

Not knowing what the elevation of my low point of the layout will be relative to the floor, I planned this layout with a low point set at Prospect Junction near the crossing of the South Platte River. The line climbed around through North Yard, achieving a climb of +2.5" by the time that the main line reached Utah Junction. The climb continues, just as in the prototype on 1% or less grades through C&S Junction, Arvada, Leyden and Barbara Gulch. By the time the main line reaches the bridge carrying US-36 over the railroad, and enters Rocky, the main line has climbed to +8.5" over the reference point at Prospect Junction.

Main line climb through the Rocky-Big 10-Clay LDC. All elevations are relative to the height of Prospect Junction.

 I made the decision to provide a flat spot in Rocky up until the point where the Rocky Flats branch joins at Rocky Junction. From here, I have the main line climb, slowly at first, but with the grade growing. The prototype grade becomes 2%, but I found that I needed a little stiffer grade to achieve the desired elevation climb. In the end, I settled on 2.5%, with the turnouts not included, so the actual grades will be a little less.  By the time the main line reaches the west end of Rocky siding, the main line has climbed to +9.6". The main climbs another inch by the time the Big 10 windbreak is reached, and to +11.63" by the time that the wind break ends. The line reaches +12" by the time that Clay siding starts, a climb of +3.5" from where the line entered Rocky. The climb continues through Clay, reaching +14.75" by the west turnout.

At this point, my vertical clearance is 5.75" rail head to rail head. In N-scale, minimum clearance as specified by the NMRA is 1.72", and I treat it as 2". So, at this point, I do have about 4" of clearance from the top of the lower train, to the rail head of the upper main line. If I subtract out a minimum of 2" for a thickness of the bench work, that leaves only 2" which is not enough. Fortunately, I can keep the mainlines from crossing each other for a while, allowing me to climb to an elevation of +16.5" almost directly above Rocky Junction (located at an elevation of +8.5"), which allows me to double the clearance between the top of the equipment on the lower deck and the bottom of the upper deck. Is this enough? Time for a mock-up to see how it looks.

Mockup of the two levels with an 8" rail head to rail head height and a 2 inch bench work thickness.

I used an adjustable bookshelf to create a simple mockup of the bench work where the two levels overlap. The plan has the depth of the bench work at this region set as 12 inches, and, and my bookshelf is only 11", but it gives you a good idea. With a few clamps to hold a strip of wood to simulate the full thickness of the bench work, and a few binder clips to place a couple of led strip lights under the bench work to provide light, I proceeded to arrange a couple of pieces of Kato Unitrack and a couple of 60' Atlas N-scale passenger cars I had handy into the scene. My conclusions:

1. Without the led lights, the lower deck is clearly too dark. And the viewing height versus eye level will be crucial. The shelves I used were lower than the likely layout height at this transition, but there is clearly a relationship.
2. Surprisingly, the height is workable. You can get your hand in to fix a derailed car if necessary, provided that the shelves are not too deep. The scene is also helped by not having foreground structures that reach the bottom of the upper deck.
3. It is also apparent that the lower level works best if the scenery intended to be viewed during operation is closer to the front. This will also help the lighting needs of the layout.

Another view from a higher viewpoint and with the lower level track about 6 inches back into the scene.

All in all, I am pleasantly surprised that this is enough clearance, at least for a brief transition if the scenery is carefully planned. However, I would in general prefer to get a deck separation (track to bottom of the lower deck) of closer to 12-14" in general. I will need to do some further analysis to help determine exactly how to manage this scene.

Another design concern is as to whether the Big 10 Curve is large enough to feel realistically "large" versus a train. A typical coal train may be about 13.5' long. Laying out such a train through the Big 10 Curve shows the following.

A 13.5' Coal train (In Orange) through the Big 10.

As the train enters Clay, its tail would still be in Rocky. However, by the time the train clears Rocky, its head would be passing by it on the siding above in Clay. There should be nearly 1.8 miles between the sidings and a Moffat Coal train would be approximately 1.3 miles long. So, the sidings are a little close. But does it give the right feel? I think it is pretty good, but if possible, a little more length would be good to include between the sidings.

My conclusion - the plan is nominally workable, but should be revisited. The plan can continue onto the second deck, but further consideration may be necessary to see if some additional improvement can be achieved to increase the deck separation, manage the viewing height, and lengthen the distance between Rocky and Clay. While 1.8 miles (about 59') is probably impractical, perhaps something greater than 13.5' should be targeted.

Cameron Turner