Gauge Options for HO Track

[rmbarry]

I am getting ready to hand lay HO scale track.  Before I order the rail stock, I first need to know what gauges are used for Mainlines, Branchlines and sidings.  I presume that Code 100 is for Mainlines, Code 83 or 70 is for Branchline, and Code 55 is for sidings.  Am I correct in my assuptions?  Will Code 55 rail work with standard HO scale wheel sets or is it only used for Proto 87 wheel sets?

Thank You,

 Ray B. 

 

[Gary UK]

Dont take this as the diffinitive answer, but this is the way i see it.

Code 100 is overscale and is the old order from yesteryear.

Code 83 is used on mainlines, everything else is used on sidings, secondarys.

[tomikawaTT]

When I saw your thread title, I immediately started thinking, "What gauge (prototype) track can be represented using HO (16.5mm) off-the-shelf flex track."

What you actually meant to ask is, "What size rail is appropriate to model the various weights of prototype rail in HO scale, standard gauge?"

So, since 'code' is actually the height of rail in thousandths of an inch, the answer(s) are:

• Code 100 (de-facto standard for older flex, sectional and toy-train track) is oversize for any use, but can represent mainline rail and is the best choice for hidden track.
• Code 83 is more appropriate for heavy-duty mainlines, since it approximates the scale size of 132 pound (per yard) rail.
• Code 70 is approximately equivalent to the rail found on light-duty main track, branchlines and shortlines, and for yard and industrial thoroughfare tracks.
• Code 55 is appropriate for the far end of single-end yard tracks, and for light industrial sidings.
• Code 40 may be used for trackage which will never be traversed by a locomotive or a heavy freight car.  It is (barely) adequate to support a loaded pre-WWII box car.

If you are modeling pre-USRA (19th century and slightly later) prototype, code 100 and code 83 are oversize, code 70 is mainline, while code 55 and code 40 climb one rung up the explanation ladder above.  If you are handlaying track to prototype specifications, the other available codes (80, for one) may be more accurate.  Prototype rail comes in a wide variety of sizes, everything from 12# mine cart size to humongous girder rail used under traveling dock cranes.  The choice in modeling isn't quite as wide, but it is possible to come within reaching distance of the right appearance.

Chuck (modeling Central Japan in September, 1964)

[dehusman]

First a terminology lesson so you don't confuse people.

Gauge is the distance between the rails.  For HO standard gauge it is the same regardless of the size of the rail.

You are asking about "code" or the size/height of the rail.   code is the height in thousandths of an inch.  So code 100 rail is 100 thousandths or .100 inch high.

Real rail is measured in pounds per yard.  So 152 lb rail weighs 152 pounds per yard.  Real rail is also era specific.  In the the 1800's 75 lb rail might be on the mainline, but WW1 they might be using 90 to 115 lb rail.  Up until the last couple years most railroads have be using rail about 136 lbs on the mains.  Within the last couple years the UP and BNSF went to 140 lb rail.  Some of the biggest rail was used by the PRR, 155 lb rail.  In addition the same weight may vary in size depending on the manufacturer and rail design.

Here are some common rail sizes:

155 lb = 8" = .092"

140 lb = 7 5/16" = .084"

136 lb = 7 5/16" = .084"

115 lb = 6 5/8" = .076"

100 lb = 6" = .069"

90 lb = 5 3/8" = .062"

75 lb = 4 13/16" = .056"

So depending on your era and how close you want to adhere to prototype, you can use a mix of code 83 and code 70, with really old industrial spurs maybe in code 55.  If you are modeling modern times, just use code 83 and code 70.  If you are modeling the PRR Main Line (Phila to Pittsburgh or New York to Washington) you can use code 100.

Dave H.

[loathar]

Code 55 and 40 might give you problems with older wheelsets that have larger flanges. (flanges may ride up on rail spikes) Stick with 83 and 70 unless you want to replace your wheelsets with proto 87 style wheels. (I've heard those have a tendency to derail but I've never used them)

Code 83= .083" tall. code 70= .070" tall. 55=.055". 40= .040"

[fwright]

Code 55 and 40 might give you problems with older wheelsets that have larger flanges. (flanges may ride up on rail spikes) Stick with 83 and 70 unless you want to replace your wheelsets with proto 87 style wheels. (I've heard those have a tendency to derail but I've never used them)

Code 83= .083" tall. code 70= .070" tall. 55=.055". 40= .040"

RP25 flanges - normal HO production since 1970s - will clear Micro Engineering (ME) code 40 and code 55 flex track just fine.

The older Rivarossi, AHM, and IHC are the primary manufacturers that did not follow NMRA RP25, and had deep flanges.  These will not run on most code 70 track either.  Depending on how deep the flanges actually were, some of these models could even "rumble" (hit the spike heads) on code 83 track.  Rivarossi switched to RP25 for North American prototype in the '90s - a few models like the Heisler came with RP25 flanges from the beginning (1970s).  IHC has been slowly changing to RP25 in the last few years, most notably in their Premiere Line.

The difference in flange depth is easily spotted once you have seen a few examples of each in the hobby shop.  I just avoid buying locomotives with deep flanges unless I already have a plan to change the wheels out.  Cars are more easlily fixed by replacing the wheel sets.

If you spike code 55 or code 40 handlaid track, you need to use the very smallest spikes from ME or the near scale or smaller spikes from Proto87 Stores to provide clearance for RP25 flanges.  Gluing or soldering the rail instead of spiking solves the issue, too.

The NMRA wheel RP (Recommended Practice) lists different wheel codes, which describes how wide the tread is.  Standard RP25 for HO uses code 110 wheels (.110" wide) with a flange depth of .025".  "Fine scale" wheels in HO use code 88 wheels; the flange depth doesn't change much.  Exact scale - commonly called Proto87 - uses wheels equivalent to NMRA code 64, but the profile is scaled from the prototype.

Fine scale wheels (code 88), which have a much better appearance when looking at the width of a wheel, generally run acceptably on normal NMRA-spec turnouts, but the normal code 110 wheels will be quieter and smoother going through the frogs.  Some models are now coming equipped with code 88 wheel sets, which is why I bring this up.

Proto87 wheels will not work on NMRA-spec turnouts, and NMRA-spec wheels will not go through Proto87-spec turnouts.  So Proto87 remains a pretty much all or nothing commitment at this time.

Somewhat confusing?  Yes.  But it's a whole lot better situation than the plethora of standards used by our OO friends in rainy Great Britain. 

yours in wheel and track relationships

Fred W 

[dknelson]

I think that capturing the gradations in sizes of rail for different purposes is probably as important if not more important than the sizes themselves.  That is, Code 83 is more realistic than Code 100, but if you have Code 83 for everything -- the mainline as well as for the most run down and marginal grain elevator spur -- then that detracts from the realism.  Stated another way, using Code 100 for mainline, Code 83 for secondary lines and yards, and Code 70 and 55 for lightly used spurs and branchlines can look more realistic than using Code 83 or Code 70 for everything, because you are conveying hte idea of different sizes of rail for different purposes.   

A word in defense of Code 100 .... which is admittedly far too large for nearly any scale rail except for portions of the Pennsylvania Railroad.

David Barrow, who had one time had handlaid Code 70 on his layout, switched to Code 100 prefab flex track for his later layouts due to the superior mechanical strength.   Of course he was and presumably still is changing his layout constantly.   Code 100 is very forgiving of imperfections and seasonal shifting.

Dave Nelson

 

[larak]

I think that capturing the gradations in sizes of rail for different purposes is probably as important if not more important than the sizes themselves. 

A word in defense of Code 100 .... which is admittedly far too large for nearly any scale rail except for portions of the Pennsylvania Railroad.

Dave Nelson

 

  

I have to agree with Dave 100%. Code 100 looks OK (not perfect but OK) when ballasted and the gradation from 100 to 83 to 70 for different lines is a nice touch. Kind of like the subtle effect you get with superelevation. Very light codes are also trickier to work with. Make life easy on yourself.

Also, I believe that the Hudson River lines use pretty heavy rail these days. The west shore looks like 132# or so and I would think that the east shore is heavier - having passenger traffic at higher speeds. I'll have to bring a ruler next time.

Karl 

[RR Redneck]

This might be the toy train fanatic philosiphy in me, but I like Code 100. It worked ecellent for me. Scale is good, but whatever works, works.

[Don Gibson]

GAUGE? allee same - HO as defined by the NMRA. Got gauge? No? Get same.

CODE is 'size' of rail - height / thickness / appearance - simulating Weight in the world of railroading. 'What is ''Right'' is relative - replaced by economics and the fact that only you look at it.

Code 100 is oversized, Code 83 is a compromise, Code 70  represents 90-100 lb mainline during the Steam Era. Code 50 and 40 track is only available for the 'Do-it-yourself modeler as is proto 87. But it's all HO gage.

Commercially, code 55 is being offered in 'N' scale track - and oversized. As I said, we are faced with 'compromises. If you like the 'STEAM' ERA - pre 1955 - code 70 & 75 will look the best.

PROTO 87 is for hand laying, perfectionists, nit pickig types, or sadists  - in that order.  Probably for my next layout. KEY is matching P87 wheel flanges to flangeways. RP flanges are too wide.

I HAVE unused code 100 Shinohara left over from previous layouts - too good to throw out - but all my new track is 83 (passing siding) or 70 (yards) - Compromise, compromise - but I also want to live with it.

Turnouts, I don't compromise as they are the principle cause of derailments. THERE, hand laying pays dividends.

http://www.troutcreekeng.com/bkho.html

 

[fwright]

I am getting ready to hand lay HO scale track.  Before I order the rail stock, I first need to know what gauges are used for Mainlines, Branchlines and sidings.  I presume that Code 100 is for Mainlines, Code 83 or 70 is for Branchline, and Code 55 is for sidings.  Am I correct in my assuptions?  Will Code 55 rail work with standard HO scale wheel sets or is it only used for Proto 87 wheel sets?

Thank You,

 Ray B. 

Ray

There's been a lot of confusing information thrown out here in repsonse to your questions.

1) Commercial flex track is available in HO in code 55, 70, 83, and 100 rail.  Major brand commercial turnouts are available in code 70, 83, and 100.  Turnout kits and custom turnouts can be easily ordered for any of the rail sizes from several suppliers.  But you asked about handlaid track, not commercial.

2) You can hand lay track with any of the HO rail sizes, including code 40.  Common techniques for hand laying HO track include spikes into wooden ties, gluing rail to ties using Pliobond or Barge's cement/glue, and soldering to PC board ties.  Any of the methods work with any of the HO rail sizes.  If spiking rail, you must use near scale size spikes with code 55 and 40 rail.  Micro Engineering makes some small spikes called micro size spikes; the Micro Engineering line is available through Walters and various dealers.  http://www.proto87.com/ sells stainless steel scale and near scale spikes.  Don't let the Proto87 name mislead you - just about all their products can be ordered for, or used for, either NMRA-spec or Proto87-spec turnouts.

3) When you hand lay track, you decide what spec you will build your track to.  Track specs should match the wheels being used.  NMRA RP25 wheels will work on NMRA-spec turnouts and track down to and including code 40 rail.  As I posted earlier in the thread, there are/were a few European manufacturers who did not/do not use the RP25 standard.  US production prior to the 1970s often did not follow RP25 either.  The pre-RP25 NMRA flanges were slightly deeper (up to .035") and will likely not run on code 40 rail.  Whether these earlier models will run on spiked code 55 rail will depend on the spike head height.  Code 70 rail has no problems with anything except deep European flanges (can be .039" or larger).

4) Match the rail size to suit your prototype's practices.  The November 1962 Model Railroader Clinic had a great article on prototype rail size practice, and matching model rail code sizes.  You can obtain a copy of the article from our forum hosts.  For my 1900 era short lines, I use code 70 on the main, and code 55 (mostly handlaid) on secondary trackage.  On the HOn3 line, I use code 55 on the main and code 40 on secondary (again, mostly handlaid).  The code 70 and 55 for the main lines are slightly oversize for my era, but were chosen to emphasize the contrast between standard and narrow gauge.  I personally agree with those who choose to use a variety of rail sizes to contrast different uses of track.

hope this helps answer the questions

Fred W

[jockellis]

G'day, Y'all,
This has been a most interesting post to read. One of my colleagues in the non destructive testing industry tells me that the track on Atlanta's MARTA commuter rail is much taller than that on the freight railroads. But it is thinner. Wierd! Maybe Code 100 would be prototypically correct were the layout builder running commuter passenger service.

[dstarr]

 

A word in defense of Code 100 .... which is admittedly far too large for nearly any scale rail except for portions of the Pennsylvania Railroad.

David Barrow, who had one time had handlaid Code 70 on his layout, switched to Code 100 prefab flex track for his later layouts due to the superior mechanical strength.   Of course he was and presumably still is changing his layout constantly.   Code 100 is very forgiving of imperfections and seasonal shifting.

Dave Nelson

Another defense of code 100.  If you paint the rail it looks much lower than a bright shiny nickel silver rail.  Code 100 painted rust color looks lower than unpainted shiny code 83.  A fairly quick and easy pass with a paintbrush down both sides, followed with a wipe off of the rail heads and your code 100 looks a lot closer to scale.