track types

"OW5" is a term referring to "O scale, wide gauge , 5 feet".    It is similar in thinking to ON3 which means O scale, narrow gauge, 3 feet, or ON30 which is what Bachman calls their narrow guage which runs on HO track that is about 30 inches in O scale, actually 32 I think.    the term probably originated with the Proto-48 guys to poke a little fun at the tradional O scalers.

O scale traditionally both 2 rail and 3 rail has used a track gauge of 1 1/4 inches.    This scale out to 5 feet in O scale hence the term OW% because it is wider than standard gauge 4 feet 8 1/2 inches.    so most O scale 2 rail (and 3 rail) is also OW5 if  you want to use the term.   Most O scalers don't  use it that I know.

You are right rail "code" refers to track height in 1000ths of an inch.    so  Code 125 is 125 thousands high which is 1/8 inch.    Code 250 would be 1.4 inch.    Historically most modelers used code 172 but that changed as other options became available sometime after 1950.      I don't think many new layouts are built with rail that high anymore but it still probably half the height of 3 rail O gauge rail.

Probably many modelers would use code 148 for mainlines and code 125 for sidings if they wanted to use 2 sizes.    some also use some code 100 for industrial track.    Not too many people use code 100 for standard gauge modeling. 

If you want to model a busy heavy duty line, code 148 or larger would be a good idea.     If you want to model a spindly old shortline, code 125 or 100 would make more sense.  

The code number does not mean all rail that is code 125 for example is the same.    The manufacturers don't always make the rail the same and some brands maybe thicker and wider than others.     It is workable, but requires a little fiddling to get a good transistion. 

When change from from one side rail to another,  you simple shim up the smaller rail to the height of the larger rail either in the rail joiner or under the ties.

I have a PRR MOW guidebook and if I remember to look I will see what it says about rail.   they did have specs and the mainline was very heavy.    Also the tie spacing was much closer on the mainline than on sidings.

thank you so much!   this info helps tremendously

Some 2 rail layouts, such as the Appalachian & Ohio, use code 125 for the mainline and 100 for sidings and yards. Personally I find that it has a subtle visual effect of making the track look longer. It is also less expensive and much easier to hand-lay including scratch built turnouts. No bending or soldering jigs are required.

Of course, the A&O isn't the Pennsy which seems popular with many on this forum so that may not be best for you. There are many A&O coal branch sidings that are practically buried in the mud, and code 100 makes this easy to model.

Also, scratch building turnouts in-place allows everything to fit in much smaller spaces than with commercial turnouts and soldering jigs. There's nary a turnout with a true straight leg. In one yard the turnouts are all curved in the form of a pinwheel.

Your mileage may vary. Regards.

thx...yes...i'm building a SW PA coal-themed fictitious branch of the B&O which will junction with a local short line, so 125/100 would likely work well.

i initially was opposed to hand laying (time), but have started to reconsider for the turnout reason you mentioned.   many of the turnouts on the proposed layout would be for scenic/non-functional purposes, so the expense, bulkiness, and radius restrictions of the commercially available ones got me thinking more about the layout flexibility gained from hand-laying being a decent move.

will continue pondering

The other thing with the code (from my years of reading Model Railroader) is that it approximates prototypical track, that code 100, besides being .100 inches high, also approximates prototypical 100 pound rail (I think it is per foot). That could be in HO scale, where let's say 125 would be more like 100 pound rail in O (and I only offer this as background).

The only concern I would have about using 125/100 would be making sure any equipment you buy that flanges are sized properly. I looked at the NMRA website for the heck of it, and their so called "deep flange' standard would still work with code 100 track (.095 inches), so I suspect that any scale equipment made in relatively recent times will work fine

@vacuefactor posted:

thx...yes...i'm building a SW PA coal-themed fictitious branch of the B&O which will junction with a local short line, so 125/100 would likely work well.

i initially was opposed to hand laying (time), but have started to reconsider for the turnout reason you mentioned.   many of the turnouts on the proposed layout would be for scenic/non-functional purposes, so the expense, bulkiness, and radius restrictions of the commercially available ones got me thinking more about the layout flexibility gained from hand-laying being a decent move.

will continue pondering

Depending on what era you model even those may be considered "heavy" rail. 

Many of those branches in the coal and coke era were light rail and 15 mph railroads such as the PRR Redstone Branch in the Uniontown area that I plan to model.

Year is 1958….  Will have a B&O em-1, s-1a, doing coal drags…and short line F3 units with mixed freight on the lines if that means anything with regard to rail size.