# Code Track & Reading Drawings



## PhilG (Dec 23, 2011)

I've used the search to see if this has been discussed but didn't find anything. I hope I'm not repeating topics especially since I'm new. The two questions I have are;

1) What exactly is coded track? What do all those numbers mean and what is the best track to get (that last part might be a can of worms)?

2) When looking in model train magazines I see the drawings of the layouts and they print numbers usually around the radiuses, which I assume is what they are. But in the description of the layout it lists a minimum radius and some of the numbers are smaller. So I must be wrong on that account. Is there a list or key to be able to read these drawings accurately?

Thank you for your time.

Respectfully,

Phil


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## CasperFLSTC (Nov 7, 2011)

PhilG said:


> I've used the search to see if this has been discussed but didn't find anything. I hope I'm not repeating topics especially since I'm new. The two questions I have are;
> 
> 1) What exactly is coded track? What do all those numbers mean and what is the best track to get (that last part might be a can of worms)?
> 
> ...


Welcome to the forum. I was in your shoes and while it seems a short time, well it was . Google is your friend in this (and many endeavors). As for the "coded track" that one hit me as well (as did the ohter) but a quick search can bring you many links such as this one (http://www.building-your-model-railroad.com/model-railroad-track.html) which help lots to explaining it. As I understand it the "codes" primarily refer to the "height" of the rail. For HO the most popular are 83 and 100. And lastly if you "mix" track you need some form of a transitional rail joiner to account for the difference in height. I'll let the more seasoned experts fill in any blanks on that score that I missed or am not aware of.

As for #2 I beleve that what you are experiencing is mathmatics. For example an 18" radius curve actually takes up 36". Therefore the 18" is actually referring to the distance from the beginning of the curve to the mid-point. Why they did that I have no idea. Makes more sense to me to say it's 1/2 of a 36" radius  Originally I thought they were degree references until I started seeing it referred to as 18" curve requiring at least 36" of space. So it is expressed as an 18" curve.

Again, welcome and the only words of advice I have at this point is read, read and then read some more. It seemed everythime I learned something I had kicked over two more ant hills of stuff to figure out.


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## PhilG (Dec 23, 2011)

Thank you Mr. Casper,

I wanted to ask the question here since getting info on many websites tends to lead to as much misinformation as good information. Learning from a group of dedicated enthusiasts is a much safer bet, plus they can usually get to the root of what you're asking even if you word it wrong or even aren't asking the right questions since they have done it before. Nothing beats experience for wise advice. I like your advice sine I love to read.

As for the math, you are probably at least on the right track, so to speak. But I'm still not sure. For example a drawing that labels a curve as 46" has listed in the 'layout at a glance' box the minimum radius being 50".

Since we are really not talking about circles but arcs, it's confusing, because an 18" curve that covers less than half the circle will not take up 36" unless we are starting to talk about circumference. An 18" radius will have the far end 36" away but would have covered 56.5" of track. I'm starting to confuse myself!

I see what you are saying about the space it takes up instead of degrees in respect to the curve, but either way the numbers don't come out right, at least for me. 

R/

Phil


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## CasperFLSTC (Nov 7, 2011)

PhilG said:


> Since we are really not talking about circles but arcs, it's confusing, because an 18" curve that covers less than half the circle will not take up 36" unless we are starting to talk about circumference. An 18" radius will have the far end 36" away but would have covered 56.5" of track. I'm starting to confuse myself!



Can't speak to the 46" needing a 50" radius unless the writer was adding in 2" on each side for safety (derailments, track accessories or whatever).

I did read this morning on a MRR forum post where (for the first time I can remember seeing it - perhaps because of this question) the writer referred to an 18" radius curve. This does match to the 36" circumference.


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## sstlaure (Oct 12, 2010)

The code of the track refers to the rail height in thousanths of an inch (Code83 is .083 tall, Code100 is 0.100 tall) If you want the freedom to run ANY rolling stock, engines, etc - get Code100. All newer rolling stock will work fine on Code83, but the older stuff had taller flanges on the wheels and may hit the ties on Code83 track. I run Code100 for flexibility. Code100 also tends to be cheaper, Code83 is more realistic (tie size, spacing and rail height.)

As far as the numbers printed on the layout plans, most likely what you're seeing are altitudes.  Track plans usually clearly call out how much the track is climbing or decending so that you can plan accordingly while you're building. They'll either start at zero at the lowest point of the layout, or they'll list everything from a recommended height of the layout (main level at 42-48" and climb or decend from there.)


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## UPBigBoy (Jan 2, 2012)

CasperFLSTC said:


> Can't speak to the 46" needing a 50" radius unless the writer was adding in 2" on each side for safety (derailments, track accessories or whatever).
> 
> I did read this morning on a MRR forum post where (for the first time I can remember seeing it - perhaps because of this question) the writer referred to an 18" radius curve. This does match to the 36" circumference.


I think you meant to say 36" diameter as a 18" radius is equal to a 36" diameter measured in the middle of the 2 rails.


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## Massey (Apr 16, 2011)

OK to square a few things up here. the "CODE" of the track is the height of the rail in inches. So Code 100 track has a rail height of .100" and Code 83 is .083" This does not include the ties which vary from manufacturer to manufacturer. As stated above to go from one code to the other you will need transition joiners which are usually available in train stores or Walthers. As for which is better it all depends on the user. I prefer Code 100 but others like Code 83 better. One is not better than another, it comes to a matter of personal preferance, How many rivits you are counting or prototype accuracy.

Curves. This is more simple than you guys are making it out to be. The Radii is simple 1/2 the diameter or from the centerpoint of a circle to the outside. The Diameter is the length from outside to outside crossing through the centerpoint of the circle. We dont deal in arcs and other engineering terms just simple geometry. 
Now the Radii is from the center point of the curve to the CENTERLINE of the tracks!! Not the inner or outer rails but the centerline (where the nail holes are in the ties) This means you will have some track beyond the 18" mark plus you will need a little easement just incase your engine/cars derail. None of us want our engines to meet the floor from 3 or 4 feet up so we also need to calculate in a little extra for safety. This means to SAFELY have an 18" curve making a 180° loop we need to have 40" of benchwork for track and easement. For 22" we need a minimum of 46". To be honest with you all I dont feel warm and fuzzy with only 1" of protection on each side. 

You will also see switches listed in a number. This is a ratio of length of track to amount of deflection. So a #4 switch has 4 units of length for each unit of length the divirging rail seperates. A #6 has 6 units of lenth for each unit of seperation. 

Does that help explain some of the numbers and terms?

Massey


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## PhilG (Dec 23, 2011)

Yes it does. The thing that was most confusing to me was numbers I'd seen printed in magazines that didn't seem right, but I'm sure if they had some sort of key it would make perfect sense. 

Thanks.

Phil


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## sstlaure (Oct 12, 2010)

Typically the track plans in magazines will indicate a minimum radius, but also include a scale grid to measure off of. The numbers listed on top of the track as it goes around is the height of that track either from the floor, or from an assumed zero eight. (At least that's how the plans at Model Railroader Magazine work.)


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## tjcruiser (Jan 10, 2010)

Just a follow up on what Massey said above re: track radius/diameter, given that this thread is in the general section, rather than an HO or N section ...

Some tubular O track diameter is referenced to the OUTSIDE of the track, rather than the midpoint between the rails. O27, for example, is about 27" diameter to the outer point of the ties ... the outer rail is a bit smaller diameter, and the innner rail is smaller still. Some other O (but not all) falls into this same frame-of-reference category.

TJ


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## Massey (Apr 16, 2011)

Thanks for adding that in TJ. I dont know the ins and outs of O as well as other scales.

Massey


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