My friend tells me that I can start elevating my track at about the 0 point 
go around the penisular, climbing at 2% and be at 3 inches, enough to clear the track when it crosses over. I’m thinking I’ve got to start the incline further back to make the clearance where the two tracks will cross (tunnel below). The penisular is 8 feet long starting from the bench you see on the left, out to its end. The red line is my freehand drawing to show how the track will run.
Who is correct staying a 2%?
Jarrell
You need to start far enough back to be at 2% when you pass under. Any further back doesn’t help, since the upper and lower will both rise the same amount. To get a 3" rise at 2% you need to be climbing for 150", or 12.5 feet. With your 22" radius, going to get about 69" for the semicircle, guessing from the drawing it looks like about 3.5 feet into and 3.5 feet out of the circle, which works out just about right. Remember, the 3" is going to be railhead to railhead, you clearance will be reduced by the depth of your roadbed on the upper track.
Ummm if you start the incline further back, the track will be that much higher under the “bridge” and have to climb that much higher to get over it. The distance from under the “bridge” to where it crosses over is a constant in this situation. To make it easier to calculate assume the track directly under the “bridge” is zero, reguarless of where the grade acutally begins.
If that was a simple 22" circle, that would give you 138" to get an elevation of 3". That is slightly over 2%. I am guessing you have just a bit more than 138" in this situation, so that would be right at 2% or a shade under.
I guess I’m going to have to buy him lunch… [^]
But, that’s ok… I was hoping I was wrong in this case.
Jarrell
Actually, I’m really leaning toward NOT putting an incline on this area at all. I hate to lose all that space to a mountain and a tunnel, not able to put some business’ on there with some nice sidings to switch. I know somebody with more experience could run sidings off an incline and make it work but since this is my first try, I don’t think I can and get it to be trouble free. I suppose I could level the track for enough distance (on the incline) to put in a couple of turnouts (one on each side of the penisular) , then start up with the incline again. I might could get that to work.
Hmmmm…
Jarrell
I don’t think you have room to do that. Remember, when you change grade there is a trasition, just like there should be in a curve, so it takes space to reduce and then increase the grade. If you put sidings on the grade, I think you’ll have to have the switch on the grade, and level the siding after. That shouldn’t be too hard (I hope, sinceI have some places that I will be doing it!)
I assumed that the length from “0” to the crossover is about 13’, so a 2% rise puts it at 3.12", somewhat over the height you stipulate. A 3% rise from that point will net more than 4" (without actually calculating it…I’m guessing). So, the 2% rise would work, but leave you little extra, and scale-correct, height. 2.2% would be better to get the 3.5" recommended from railtop below to the apex (and lowest point of passage) overhead.
You really should use 3.5" seperation, not 3", 3" requires a “dishonestly” thin bridge deck to work (in the words of John Armstrong). Track Planning for Realistic Operation, second edition, page 49 has a chart for up and over grades with a loop. I’m sure it’s in the third edition as well, but since I don;t have that one handy I don’t know what page. 22" radius, 3.5" seperation with a 90 degree crossing angle is a 2.4% grade, still not a problem. A handy formula is also given: grade % = (seperation distance / (6.7 x Radius)) x 100.
–Randy
Page 83, in the Third edition. Just picked it up a couple of weeks ago.
Tom
I don’t Jeff, I have enough problem just laying track straight in level areas… [:p]
Thanks for your help!
Jarrell
How about a diamond (crossing) instead of up and over?
I’d go with the up and over. Trains running up and down add interest, and a bit more operational challenge, too. You do have room there for some straight turnouts off the crossover legs, or you could go with something like Peco’s curved turnouts, with “almost” 18 and 22 inch radius curves, close enough to correct with flex track. If your point of crossover is over a tunnel, rather than a bridge, then you don’t have the “unrealistically thin” bridge deck problem, because you don’t see how small the clearance is.
That was also brought up and I’m thinking it over.
Jarrell
I like the idea of an up and over and it would be over a tunnel, not on a bridge. I think what you’re saying is after I get high enough with the incline to clear the track below I could use the curved turnouts on level ground even though it may be on a curve.
Yep, that’s an idea.
Thanks,
Jarrell
Jarrell,
Just thinking off the top of my head. If you could have your track swing farther back to the left before it enters the peninsula, then curve around to follow the edge of the peninsula, curving around the end of the peninsula and following the edge of the benchwork until it exits the peninsula, you would eliminate crossing over entirely. (The track would look like an outline of a trailer hitch ball laying on it’s side.) In addition, your grade could be less than 2% and allow for some level sidings on either side or on the end of the peninsula. If you need the elevation where the track exits the peninsula, you can start your grade farther back than at “0” and still maintain a lower grade, even with a flat siding area on the peninsula.
Just something else for you to think about in your free time! LOL
Darrell, quiet…for now