various codes for flex track

Model Railroader Layouts and layout building
1

Why the different codes for flex track? Is one more appropriate than the others? If so, why?

2

Model rail (stick, flex track or sectional) is ‘coded’ by height, in thousandths of an inch.

Prototype rail is specified by section and weight per yard. That combination, when looked up on a comprehensive table, will give the rail height and other dimensions.

Dividing the prototype rail height by 87.1 (for HO) will give a measurement in thousandths of an inch, which can then be matched against the available model rail heights.

Railroads don’t use the same weight or height of rail everywhere. Heavy duty Class 1 mainline is, typically, laid with 132 #/yd rail, but little used spurs that are embargoed to locomotives and heavy freight cars might be laid with 75 #/yd rail that was rolled over a century ago.

So, how do the available rail sizes match up with prototype practice in HO?

  • Code 100 - OVERSIZE! The heaviest rail ever laid on an American railroad, 155 #/yd, used only on a few thousand feet of track, would scale 0.0918" - code 92 if anyone manufactured it,

  • Code 83 - a little tall for 131/2/3 #/yd, short for 140 #/yd.

  • Code 80 (you might acquire it as stick rail or salvage it from reject N-scale flex) - 127 #/yd.

  • Code 70 - dead on for several variants of 100 #/yd rail as well as 105 #/yd.

  • Code 55 - dead on for 75 #/yd rail.

  • Code 40 - dead on for 40 #/yd rail, which is lighter than anything laid on a common carrier railroad since the Civil War.

  • Code 25 - worn 16 #/yd rail, suitable for 450mm (18") gauge mine cart track, or for an HO model of a 1/4 scale amusement park operation using Z-scale rolling stock.

So Code 83,

3

Thank you TomikawaTT.

So is code 83 0r 100 the more common and most used codes?

4

Well, several years ago code 100 would have been the more common. These days code 83 is probably the “favorite” in visible areas and 100 in hidden areas. Code 100 can provide somewhat more reliable operation and was (is?) a bit less costly. Many of us use a mix and throw in code 70 as well. Your question may not have a simple answer. [:)]

I would suggest that you look at other’s layouts and see what looks best to your eye. Probably not the code 100.

Disclaimer - I have lots of code 100 on my main line. (Code 83 on the mountain line). Installed it before code 83 was so readily available. With proper scenicing it doesn’t look bad at all, but the 83 looks better. A code 100 double track main next a code 70 industrial spur actually looks pretty good as it accentuates the contrast.

5

Because my current layout was started in 1983, I have a large amount of code 100. Not about to rip it out and replace it at this late date. I have also in recent years used code 83 for mainline track, have some code 70 also.

Bob