I am designing a new layout. I would like to have a double main line. I will be using code 83 track, and am planning on using mostly #6 turnouts. Minimum radi will be 24". What is the prefered centerline distance between my mainline tracks? Also, will 4" between top of rail and any overhead obstruction be ok? ie under a bridge etc. any advise would be appreciated.
Min on straight is 2", min on curve is 2 1/2" I THINK for 24" (side swipe of long cars and boiler swing) As far as overhead 3 /112" is good according to NMRA.
Thanks! I have plenty of room so I may just stick with 2 1/2" on everything.
Even though you have plenty of room, increasing the distance between tracks may not always be the best choice. In my opinion a 2" separation looks much more realistic. As you move the tracks farther apart they begin to look more “toy-ish.”
Okay, let’s say you were going to have 2" sep on straight areas (narrower for appearance sake), and 2.5" in curves (I concur that 2" at curves is risky at lower radii)…
How would you manage transition? If you widen out the straights prior to curve, you’ll negate most of the appearance issues, and in fact it might be worse - track would look ‘wavy’… But if you don’t, if you enter the curve at 2" sep and ease out the outer curve to achieve 2.5" within a reasonable distance, then won’t you still have a “choke point” during the first few inches of curvature where you may have long cars/locos butting heads and such?
???
Casey
I use 2" seperation on the straights, and 2.5" on the curves. I widen the spacing during the easement section of the curve. I also use a 4" seperation between the railhead and underside of a bridge. This works for my double stacks. Although you may want to check any double-stack or autorack cars you have to make sure.
Nick
HD1487,
I agree with Nick - use 2" separation on the straights and 2.5" on the curves. I suggest you make a template of the curve you want with transition spirals (easements) to help you get the separation correct, as Nick suggests with the easements. I built templates prior to our club’s laying out the track plan and they worked great. You can even use the same radius for the parallel tracks, as the template helps you locate the tangent tracks and the separation at the middle of the arc of curvature. You won’t really notice the fact that the curves are the same radius (although as the radii get smaller, the illusion might be lost). Building a template(s) takes a little effort but will save you a bunch of time.
Mark C.
May I suggest using cardboard or brown wraping paper and TRACE the track on it then cut it out… This is the poor mans template system.
Some double track truss bridges specify 2-1/4", like this Walthers:
For new trackwork in heavy-traffic territory, UP (and possibly others) has spread their track to 21 feet on centers (about 2 7/8 inches in HO.) If you model ‘old track, new second track,’ 2 1/2 inches on centers is appropriate. 2 inch spacing, widening the center-to-center distance on curves is the better bet if you are modeling a line that has been double tracked for a while. No matter what spacing you choose for your track, entering curves with a smooth transition is a must, both for operation and for appearance. Use a 1/2" offset on the outer track and a 1" offset on the inner track at the end of each curve and your rolling stock will be very happy!
The trick is to offset the center of the circles. This is how i designed it in CAD, when I actually built things in place what I did was start the inner curve (for 90 degree corners) about 1" sooner than the outer curve, and carry the inner curve 1" further. That way, for 1" of length at the start of the curve, the inner track is already veering away from the outer. My spacing on straights is 2". The curves have been tested with 85’ passenger cars and anything else with a lot of overhang - GG1 electric locos in particular. Everything clears. A torture test is an Athearn 85’ hi-cube boxcar, just a spare junker that is used to test paints since it’s far to modern to run in the 50’s. Talk about huge overhang - the trucks sit in closer to the middle than a typical passenger car and so it has HUGE overhangs on the ends. If this car can manage without sideswiping anything, than anything will run.
–Randy
k how long is a # 5 switch?
i have templets for
#4 9 inches
#6 10 7/8 inches
everyone agree with these?
thanks
Depends on who makes it. There’s no real standard for the length of a turnout. The one constant is that if it’s a #6, it diverges 1 unit for every 6 along the straight route. If it’s a #6, that has to be the same.
–Randy
k i see i have a "gandy dancer " templet set its years old but like i said no # 5 guess i need to buy one lol thanks
If you are using Walters - I believe the dimensions are in the Walthers catalog. Or pick up one of the MRR CAD programs, they have track libraries of all the popular brands of track. And XTrack is free. 3rd PlanIt and CadRail have free trials.
–Randy
I just finished my new layout mainlines.
I use 30 inch minimum radii, so I laid one track, then used a one inch thick wood block
as a spacer as I laid the second track. I slide the spacer along the ends of the secure ties and snug the lose ties up to the spacer and hold for nailing. I maintain 2 and 3 sixteenths space between my mains.
For your 2 and a half spacing, you may want to use a five quarter thick wood block. File away material on 2 corners for using in inside radius situations.