# Distance between parallel tracks?

Discussion in 'HO Scale Model Trains' started by SteveInBama, Feb 6, 2007.

1. ### SteveInBamaNew Member

Hey Y'all,
I'm building a layout with Atlas 100 36" flex that will have two lines side by side. Planning 24" radius turns, wtih no oversize rolling stock and all diesel engines, no long Big boys. Although I plan on about 8 switches, I havent yet selected the size or type.
Here are my questions:

Q. 1. How much distance from the center line of one track to the center line of the other, that parallels it, should I plan?

Q. 2. Is there a relationship of the distance between the track and the size/number type of switch? i.e #6, #8 or whatever, both to connect the lines and to have branches? ( I plan not to use any switches in the curves/turns.)

Q. 3. Are there any special things I should watch for - besides some expansion joints to keep from buckling track -- when I use 36" flex track and the switches?

Thanks,
SteveInBama
2. ### jeffrey-wimberlActive Member

I don't go less than 2 1/2" between center lines. I need space for 1:1 fingers to get in there in an emergency.

on parallels 2"
on your 24r curves 2 1/8"
but I've got skinney fingers
solder the joints on the curves!

Hi Steve,
I use snap track and 36" flextrack. In response to:
Q. 1. How much distance from the center line of one track to the center line of the other, that parallels it, should I plan?
Straight runs I will go 2"
Curve 18" and 22" radius 2 1/2" if I am running passenager cars 90' then go 2 3/4" also leave more room their turning radius is greater.

Q. 2. Is there a relationship of the distance between the track and the size/number type of switch? i.e #6, #8 or whatever, both to connect the lines and to have branches? ( I plan not to use any switches in the curves/turns.)
The relationship you need to concern yourself with is the track code (i.e., 100 or 083) use the same code. Other then that not that I am aware.

Switches (turnouts) - Commonly used switches are #4 and #6. The #4 appears to be equal to a 18" radius curve and I use it for slower moving trains such as branch lines due to the tighter turns. The #6 I use for faster trainings on the mainline so not to slow the train down for the turnout. This does not mean you cannot use only #4's. In my last layout I had used #4 and #6 turnouts serving the same purpose, just at opposite ends of the table. The #4 was hinden in a tunnel.

Q. 3. Are there any special things I should watch for - besides some expansion joints to keep from buckling track -- when I use 36" flex track and the switches?
My experience has been when encountering turns to ensure the curve is smooth and that you do not accidently reduce the radius of the curve. The other issue is trimming the excess track or plastic ties. I just bought a Dremmel and find it trims the track clean and makes the track laying lot easier. As develop my new layout I am only using flextrack.

Jeff:thumb:
5. ### prodigy2k7Member

I discovered that tehre are two inches between centerlines when using turnouts for parallel tracks...Let me get a picture of what I got so far...
The turnouts on the left are #6's and the turnouts on the right track are standard turnouts (18" radius turn)
Even though they have tighter turns than one another, if you connect two alike, they both seem to be 2" apart...
All 3 rails in this picture are 2" apart...
Note: Notice how the cork road bed isnt touching, they are slightly spread apart from each other...
Hope that helps
6. ### prodigy2k7Member

BUMP - no replies? I took a picture for nothing... lol

Hey Prodigy, I like the picture, but if you try keeping your track 2" on curves you may encounter issues with the 50' freight cars and definitely with the 90' passenager cars. I will not go any closer then 2 1/2" on curvers, do not like when things go bump on the layout.
8. ### nhguyMember

I'll echo what Jeff and others have said. When it comes to curves you have to increase the center lines between the tracks for car clearences. On most of my curves the track increases from 2 inches to 2.25 inches. On tight curves it increases more.

I have a helix that I'm starting to build. The track clearences in there have incresed to 2.75 inches. Because I'm going to run 80' passenger cars through there at the same time as 40 and 50 foot freight cars i need the extra room again for clearences.

One other thing. They are called: easements. You want you track to 'flow' through the turnous. Easement are nothing more than a gradual reduction of curvature going into or out of a curve. A good way to do this is to lay your curve out and mark where it is through it's total radius. Get a thin stick of lumber or flexible steel rule about 3 feet long. From the center of the curve start following the curve with the stick and pin it on both sides in place with plastic top push pins. Continue this to where you connect with the switch track center. Now draw a line from the switch track center to where it intersects with the radius of the curve. This is your easement. Cars will flow through without derailing because of a sharp sudden curve in the track. It looks more prototypical too.
9. ### prodigy2k7Member

I wasnt talking about curves, I was talking about parallels and what I did for my parallels...thanks anyway
10. ### NazgulActive Member

One thing to consider is the type of throws you are using. If you're using under the table machines or manual switches...no problem, but if you're using manual ground throws like Caboose Industries', then 2" will be a problem and require that you move the throws out of the way and use a stiff wire to throw the turnouts.
I like your track work btw.
11. ### prodigy2k7Member

True, I forgot to say that, I had to clip off the long pieces for turnouts lol...where the actual throws are at...notice on my picture I dont ahve any... all under table switches
12. ### NazgulActive Member

I thought that was probably the case, but I thought I would mention it. I didn't realize the problem on my layout and had to improvise...keep up the great work!
13. ### prodigy2k7Member

lol I didnt realize it either, luckily I was planning on doing under table machines anyway
14. ### brakieActive Member

I like 2" centers..I really like your track spacing..You see I do not and will not accept derailments as part of my operation plan.

Food for thought on yard track spacing..
For yard tracks I like 1.5" inches so it looks like a real yard.
Like so.

15. ### RioGrandeMember

I wouldn't rely on turnouts to set your parallel track distances. Trim them so that they fit what you choose. John Armstrongs Track Planning for Realistic Operation recommends 2-inches for HO as a minimum track center on straights in yards. On sidings on mainlines it would be more realistic to give a little more distance. John recommends 2 1/4-inches on tight curves like 22-24-iknch and less on more generous curves because over hang is liess an issue.

Don't forget easments where you transition from straight to curves - essentially a spiral radius beginning at straight and transitioning over 14-18 inches of distance until you are at full radius of whatever (24 or 30 inches for example). On average, about a half inch of offset to the outside of the tangent is needed from the curve to get a transition.
16. ### Santa Fe JackMember

I have a double crossover (Walthers Shinohara code 83) in my layout, and the two parallel tracks are 2 inches on center. And there's no changing it. Since it in the middle of a straight run, it will work fine, but at either end, I have made the track diverge slightly so that when it comes to the curve, the centerlines are more like 3 inches apart. I have some long cars with lots of overhang (intermodals) so I need a lot of room on the curves.

- John
17. ### hiscopilotMember

I am planning my layout with 2.5" between parallel centers and I think it plays out to slightly more between curves. I am only doing that because I want to be able to handle the trains if needed. I have never read any books or anything. This was partially a premade track plan, so I know it had been tried already and worked.

Good luck.
18. ### TorpedoMember

OK, but I thought prototypes typically run 13' spacing, which I make to be about 1.8 inches for HO. Do they run less in the yards, or do I need a refresher course in math?
19. ### TorpedoMember

Done. Hope he wins. Let us know. :thumb:
20. ### hiscopilotMember

Thanks Torpedo! These contests are usually won by people constantly dumping their cookies and resetting their routers... so we'll see. Thanks again!