I finally am able to begin constuction on a layout in HO scale! (The last one was taken down after a sewer pipe collapsed in my parents basement in 2003!).
The table is an L-Shape with a 4x* sheet of plywood perpendicular to a 4X 6 sheet of plywood with a narrow 1 foot wide “bridge” connecting the two outermost ends of this “L” to make the track have continuous running in a triangular shape.
I am planning on using Atlas code 83 track on 3 inch centers with the outer loop having a 24 inch radius. I have already purchased all of the sectional track. Would it be okay to make both the inner and outer loops 24 inch radius, since the track is a triangle and not a closed round loop, i can keep the three inch tack centers by using different length straight sections in the middle of the turn of the inner and outer curves. I am sorry if this is hard to understand, i am just trying to figure it out so i can start building the layout!
It depends on how close to a circle the parallel section will be. If you go beyond a quarter circle you will be sure to run into problems, and you’ll still need to put in straight sections on the outer loop to keep the tracks separated.
Use a sheet of graph paper and make a scale drawing. I think that you will find you cannot do what you envision because of the curve entrances and exits you would have to generate…not with 24" radii inner and outer. The inner would be fine, and triangular, but the outer would have to be more ovoid and the curves would definitely need easements if you wanted the parallel straights actually to be parallel for much of their travel.
As long as you keep to a minimum 3" separation everywhere, you should have no problem. I would suggest you cut a piece of wood (pencil, etc.) 3 " long and use it inner rail to inner rail (or outer to outer) to ensure that you have at least 3" everywhere. One place too close together and your trains could clip each other when passing - especially if your running 80’ passenger cars.
You might want to see if the place you bought the 24" radius will exchange it for 22" and 18" radius sectional track. You cannot lay a half-circle of 24" radius on a 48" wide board. The 24" radius measurement is from the centerline of the track. And the diameter is twice the radius, or 48" track centerline to track centerline. This means half your track will be hanging over the edge of your board.
So if you cannot make your boards wider (at least 4" wider!), then I recommend you drop down to 22" radius. Twice 22" is 44" which leaves 2" on each side from the track centerline to the board edge - really is marginal for the safety of any trains derailing. 22" radius is the largest practical radius for a 4ft wide board. The inside track can be 18" radius, or you can squeeze in a 19" radius by using flex track.
Sorry to be a balloon-buster. It sounds like you have a good plan in mind.
Couple of additional thoughts on your plan, you’ll probably have to cut some straights and have more than 3" in places if you use only sectional track. Since you won’t have perfect parallelism, you might want to consider using flex track for your outer curves and bending it to 27" radius - cut off the long rail after bending with rail nippers. It’ll look better also.
I think this was a 2.5" offset on the straights. Use whatever length needed to match your straight track separation.
Obviously for your triangle you will also need a few more sections in the curve. The greater the curvature over 90 degrees the less parallel the curves will be and the funnier it will look.
You could also put short sections of straight (like 1") between each curve. That would make the curve more parallel but give the outside a more jiggy operational characteristic.
Draw it out, please. You’ll find that it is geometrically impossible. Draw two concentric triangles with 24" radii nested with 3" separation at their three apexes and see what you come out with. It won’t be pretty.
Believe me, i am familiar with that concept that you could no place two cocenbtric circles with the same radii inside of eachother boundary withought having thier outtermost boundary intercept! (Was a Mathmatics major in college!) I was going for the straight sections in the curve idea. I would say the layout will look kind of like the Pocono ractrack (for those who like nascar!).
My very basic question is that to make the curves look right, you would want to start them at the same point, right? If i go with equal radius curve sections, i would have to start the innermost curve at a different point than the outtermost curve to make it work.
Just trying to work the kinks out, i played with the Right Track software and can make it work easily using 22" curves on the innermost track, but if i can get by with a larger radius, i would probably do that. I know i could flex track it with minimal expense, this way using easements which would make the curve smoother, but i have serious doubts about my track laying ability!
See this February 17th thread, Laying FlexTrack Curves, to thoroughly get your answers.
Since the dimensions here refer to N Scale => double the track spacing for HO Scale. Example: The suggested minimum of 1.25" would then be at least a minimum of 2.5"
Understood, Mike, and thanks for breaking it to me gently about your math abilities. [:)] …sorry if I seemed pedantic or insulting. I was obviously highly keyed (fixed) on your use of the word triangular and that you wanted two concentric 24" curves. I am far from educated in mathematics, believe me, so I simply took a compass and drew two nested arcs of the same radius. Whhoooaaa, Nelly! Triangle in an ovoid, yes, triangle within a triangle…when Hell freezeth over.
Respectfully, because I don’t want it to seem that I am obtuse, either deliberately or in reality, or that I am being argumentative, but I don’t believe, if I am to take what my eyes tell me, that your arcs are the same. It is perhaps just an illusory problem of perception. Also, where they meet their tangents in the inner tracks, that they will successfully permit a locomotive and train to either exit or enter them due to their abrupt transitions from tangent to arc and vice-versa. When I blow up your diagram, the transitions look considerably sharper. Maybe in reality they wouldn’t be much of a problem at all.
Perhaps our original poster will return and point out the inadequacy of my thinking. I would sure like to know, one way or another, because this is an interesting problem…besides, I should know definitely as part of my gaining experience in the hobby.
I am a mechanical engineer. I have 15 years of experience on autoCAD which this drawing was done on. I have designed complex mechanical and structural systems using AutoCAD and other more advanced design programs. Not to mention the design for my layout which you can find in my signature. I assure you that this layout can be done.
You can make the outer triangle infinitely big. Just move the upper arc up and the right most arc to the right and reconnect the ends. It doesn’t need to be as close as my diagram shows. I was just showing the 3 inch track spacing. You could make the spacing 12 ft if you want.
I apologize if i seemed overconfident, especially to you Selector, i appreciate all of the help you guys are giving me. I do not mean to make any ripples, i have been a lurker for as long as i can remember and just now got up the confidence to start posting. I love all the work that is done and displayed on the site and hope that one day you will enjoy what i have done. I just wanted to say that fist!
Second, i missed that thread posted here, it was a great deal of help. What i should do then, if i am thinking clearly, is to make the inner track a 24 inch radius and the outer loop a 27 inch raduis, this way i can always keep my three inches of track separation. If i can not do that, i will do the outer track in 24 inch and the inside track in 21 inch flex (or 22" sectional with the track seperation varing at diffferent points of the arc.)
It is great to bounce ideas here and i want to let you know i really appreciate it!
That is what I would do. Your railroad will look more like a double track main line. In the version I drew up it looks like 2 single track mains with the separation in the corners. So it all depends on what “look” you want.
One thing I didn’t see anyone mention was the need to have a wide enough space between tracks, especially on curves, to prevent side-swiping (trains hitting each other as they pass).
While, in HO, 3" is enough spacing for straight tracks; I’m not sure if it is sufficient for the curves. You may need to increase the gap. You’d be very wise to try a test set-up (particularly with your longest equipment) and see if 3" is enough.
You can use sectional track to easily incorporate easements into the curves by using larger radius segments to start, then using smaller ones nearer the centre-point of the curve and ending with larger ones again. For example… 0-0-0-24-22-20-20-22-24-0-0-0 (or whatever sizes are available). A simple, no-Doctorate-degree-needed, calculation-free way of getting some-what realistic easements.
Three inches should be more than enough. I tacked down a 180 degree curve of 18inch radius sectional track and then had a curve around the outside at 21 inch radius flex track and even my full length passenger cars (completely stock Athearns except having their couplers swapped out for Kadees) passed each other with at least a quarter of an inch between the two cars, even with my 2-10-2 on the inside track. Having your inside radius 24inchs and your outside even 26.5 inches flextrack (2.5 inch spacing) would be enough for most of the longest cars and locomotives to pass each other, at least from my experience. I’m sure that the only things that would have major difficulty would be articulated locomotives and cars (autoracks etc.), however I do not own any rolling stock of either type.
However, Chateauricher has a good point. Easements would not only make your trains look much more realistic running through your curves, it also decreases the coupler overhang as the train enters the curve, allowing for even longer equipment to pass each other more smoothly.
