Building Nolix (modified helix) - need input

[rsn48]

I'm building an N scale layout but I know more in HO have build RR's with inclines (grade) than in N scale.  And a grade is a grade is a grade, a 2 % percent grade in HO is the same as a 2 % grade prototypically.

What I am building is a modified helix as you'll see in the pic below.  I really have three questions but I'm open to any comments that will help me.  In the nolix area as you will, the trains will be going four times around the area, in the front "S" area, the train will be visible twice in a four rotation.  The first and second time (visible the second time in the S area), the track will be stack one above the other with the first time not visible.  The train will come around a third time and be visible, seperated by a river (Fraser Canyon).  The fourth time the track will not be visible.

Question one:  Without using foam, I'm using plywood roadbed 1/2 thick supported roughly every foot, how do I begin the first two feet of the grade to make it gradual?  I'm planning roughly on a 2% grade, a wee bit more actually.

Question two:  If I am making a 2.2 % grade, then .2 would be roughly 3.2 16ths of an inch.  How finely can you measure this minutely in building a 2.2 grade.

Question three:  How do I compute the grade or rise in the S section, since it isn't straight, can I just fudge and set the grade a tad higher than 2.2 in this area (since it is easier for the train to snake its way up a grade then directly up a grade).

[TiVoPrince]

Once 
upon a time a master showed me a trick.  Create a block 0.55 inches.  String together 25 inches of 'Legos' approximating the track alignment.  He used a 25 inch bit of masons line to check this.  A level placed across the legos will leave a 2.2 rise in 100 run or 2.2% grade.  Personaly I avoid grades but this seemed very efffecive and easily accounted for actual curves in real time...

[GaryHinshaw]

Here is my take on your questions:

1. With 1/2" plywood supported every 12", you should have any problems with the transition being too sudden.  The plywood won't bend enough.

2. I'm pretty picky about grades, but in building Tehachapi BC, I have found that a difference of 0.2% is barely worth worrying about (even though I thought it would be ahead of time).  Of course you care more about errors on the steep side than the shallow side, in other words, 2.0% is much easier to deal with than 2.4%.  You're correct that an extra 0.2% is 3.2/16" in 100" which is almost 1/4", which is certainly easy to measure if you have a level surface to compare to.

3. The way I actually built grades was to draw my track plan in CAD and have the program tell me the roadbed elevation at each riser location.  (I also established a level plane with a laser level, so I knew where I was starting from.)  If you don't want to deal with CAD, I would recommend doing the best job you can estimating path length along your route, and then using that length to establish elevations along the route.   You can get pretty good length estimates by chopping up your path into straight and curved sections and just using geometry to calculate lengths.

As I was installing roadbed, I used a 12" level that had a built-in tilt calibration to check points along the route to make sure they weren't too far out of whack.  (This can happen with grades on curves if you're not careful.)  The bubble in this level is not super-accurate, but you can measure grades to within half a percent or maybe a little better.   And 12" was short enough to be useful on curves but long enough to still be reasonably accurate.   (There are also smart phone apps that will display the internal inclinometer readings.)

Hope this helps a little at least.
-gfh

P.S. With grades on curves, you should err on the side of making them a bit flatter, not steeper, since the drag of the train is higher.  But if you measure path length along the curve and calculate elevations based on that, you'll be fine.

[rsn48]

Thanks, two helpful replies.  I working with a buddy on this and although it looks easy its far from it.  I prefer this to a helix as I will get to see the trains from time to time and the wait won't seem as long, plus I can do some pretty dramatic mountains along the back side of the S to scenic the area.

[Hiroe]

If you have a smartphone, you can download a "level" app that will show you the grade in actual percentages, with the phone laying flat on the plywood.

[davefoxx]

If you have a smartphone, you can download a "level" app that will show you the grade in actual percentages, with the phone laying flat on the plywood.

+1.  The S. had one at Lee Weldon's when we were setting the grade on the rebuilt peninsula of his WM layout, and it was very helpful for keeping us honest, especially in the turnback curves.

Dave Foxx

[rsn48]

What a great idea, the android app for levelling or gradients; I just downloaded it and amazingly enough, I'm impressed - cynical old Bas.... here, didn't believe it would work.

[rsn48]

Here is what I have built so far, this thread is in the N scale forum here:

https://www.therailwire.net/forum/index.php?topic=28207.0