I’ve decided to connect my 5x10 layout to my Dad’s old 4x8 by building a junction between them.
My layout has a superelevated curve at that end (the track gradually rises to bank into the turn) and it presently operates quite well.
How do real railroads handle this situation? Do they superelevate the curved leg of the turnout, and leave the straight portion level? Do they just make all turnouts level?
I didn’t have a lot of room for superelevation to begin with, so if I gradually transitioned in and out of superelevation to accomodate the turnouts, it’d be kind of pointless.
In this case the turnouts are going to deviate at the peak of the curve.
Also seems to be the case that most turnouts are either straight on both legs or a curved turnout.
I guess a good example of this kind of thing on a prototype is any place where perpendicular tracks connect at a junction. Maybe looking more closely at these situations will give me some inspiration.
Others may know more/better but I don’t believe I have ever seen a turnout on a superelevated portion of track on the prototype. If there is such a thing, I would think that the whole turnout would be on the same plane as the existing curve. I.E. Assuming that that divergent route would be on the outside of the curve, your divergent route would continue upwards at the same rise as the superelevation. If this is the case, then you would have to raise the table you are connecting, matching that plane. In any event, you still would have to ‘twist’ the track and roadbed back to a flat geometry to connect with the other railroad. That twisting probably would be a place of great problems - derailing, uncoupling.
Maybe think about it different … This is a junction and you want trains moving thru it as easy as possible. Take the superelevation out and build a flat geometry curved turnout to make the interface with the other railroad. You can still have superelevation after that turnout a couple of feet and continue thru the rest of the curve. Keep in mind that you still are twisting track and roadbed so be careful about how far away from the turnout the superelevation starts. Also, is this going to be a wye junction? If not, how are you going to get train movements back to your railroad with direction choice? Or, do it like the prototype, place a turnout on the straight flat section before that superelevated curve and parallel your main line a bit before curving away and interfacing with the other railroad.
As has already been said, the entire turnout must be in a flat plane (but not necessarily level) to operate correctly.
If the diverging track exits to the outside of the curve, the diverging path will be higher. Conversely, going to the inside, the diverging path will be lower. I have seen photos of turnouts on super-elevated track, so they do work. But you must allow ample transition space to get out of the super-elevation on both paths, just as your curves have now.
hope it works out for you - it will surely look very good done well. I’d love to see photos of the completed project.
Correct, your turnout is best left with all the tracks into it meeting it on a plane. I have tweeked some turnouts so that they diverge with slight grades, but it takes some doing. It can be done, but the changes must be gradual, and that means over about 10".
It sounds like you are using the diverging route as part of your loop? I chose to do that as well, but the real railroads avoid this practice. They prefer the through route to be part of the main, with the diverging route leading to secondary tracks of all types.
Here is a photo of a spot on my layout where I had to force the diverging route to continue to integrate into the descending main, while the through route leads to a spur.
I have built a turnout on not one, but two superelevated curves - the turnout is curved and connects two curves. The superelevation is continuous, through the turnout and, on both routes, for another 45 degrees of curvature past the frog. The tracks return to level through the easements as they become slightly divergent tangents. (What changes first is the grade. The outer curve, turnout and another 90 degrees of curvature at the facing point end are on a 2% grade. The diverging route, inner curve, begins a vertical easement to level right past the end of the frog/guard rail.) It’s been in service for over two years with no problems.
In the OP’s situation, this would put the turnout, not at the 12-o’clock position at the end of the table but rather at either 10:30 or 1:30 position. It would require an additional 50mm or so of table length to allow for the connecting track outside of the existing curve.
Note that I hand-laid my turnout. I doubt that you’ll find the equivalent in a box or bubble-pack. Since I was laying to lines established by bending flex track, only (Diety of choice) knows the frog number.
According to a retired D&RGW engineer that exact condition existed at Thistle Junction where the Marysvale branch connected. The diverging track had an awful hump and they had to go super slow to keep the train on the track. “There is a prototype for everything.”
That being said the safest thing would be to level out your super-elevated curve and install the turnout flat.
