In the process of re-building a new layout from scratch.  Is 072 the preferred track to use, or will 063 or 054 give me enough curve to create a good visual of the cars taking the curve?  I will use my existing Gargraves track for straights and buy new curves as needed.  Any suggestions appreciated.



Original Post

First picture shows Weaver Osgood-Bradley New Haven lightweight passenger cars (21-inch model length, 84-foot full scale length) on O-72 curved track. Second picture shows same two cars on O-54. Third picture shows couplers on O-72 curved track. Fourth picture shows couplers on O-54. Note increased overhang, body angles and coupler angles on O-54 compared to O-72. These cars would run on O-54 but you cannot be certain that would be the case with all 21-inch scale-length passenger cars. I have GGD heavyweight Pullman cars on order but will run them only on O-72. Don’t take a chance with the layout. At least O-72. But I find 18-inch passenger cars satisfactory on O-54.





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Having 'toured' the various scales in my lifetime with this hobby, I keep relating this sort of question back to my HO days...

And in the world of HO I am reminded that a 18" radius curve is equivalent to an O72 diameter curve in the world of O3R.   

I still have an overabundance of HO passenger cars squirreled away for another day that will probably never come again.  They're all of prototypical are the GGD cars.  And a majority of the manufacturers boxes/specification sheets for those cars has the caveat, "These cars require a 24" minimum radius curve", or some variation thereof.

A 24" radius curve in HO is comparable to an O96 diameter curve in O3R parlance.

And, it's not just an appearance issue....Melgar's photos, above, show that very well.   More importantly are operational backing up a string of 21" cars through O72 curves...or achieving a coupling maneuver between two cars on the curve....notice the last two of Melgar's photos to see the 'stress'  an O72 curve puts on the couplers.

Frankly, if it weren't for the oversized flanges on the O3R wheels, a back-up maneuver would probably leave the string of 21"-ers scattered all over the track.  Again, drawing on about 50 years of experience with HO, truck-mounted couplers (sometimes referred to as 'Talgo' in HO) are not at all preferred...or even 'allowed/accepted'... by the folks who are into the operations side of model railroading.  Backing maneuvers, in particular, are essential in operating sessions.  Body-mounted couplers...and proper weighting, among other qualities/features of the cars...are requisite. 

And, yes, I know that most of the 21" passenger cars have body-mounted couplers with design features allowing a wide swing for sharp curves.  But the alignment of these cars on an O72 curve during a back-up maneuver still results in a hefty force vector that tends to push a trailing car to the side, encouraging derailment.

I know that space to accommodate an O96 minimum O3R curve is a luxury for many home hobbyists.  But I have to agree with John (Rattler21), above.  And, since most everything else is a compromise in the O3R hobby segment, I limit my passenger car length to 15" in my O72 minimum layout....for aesthetics and operation.

Just one man's opinion, of course.  TEHO.


Capetrainman posted:

In the process of re-building a new layout from scratch.  Is 072 the preferred track to use, or will 063 or 054 give me enough curve to create a good visual of the cars taking the curve?  


As John mentions, to avoid the cars looking like they are on a 45 degree angle when rounding a curve probably 112"-128" diameter curves.

I agree with KD, the 15"/16" cars look great rounding a 72" curve, and a streamlined passenger train of 16" aluminum cars looks fantastic gliding through 96" curves.

Running 0144" curves just starts making the long passenger cars look comfortable.  My short haul N&W creeper  with 60 footers looks great.  I sold most of my long passenger cars and keep my remaining 80' cars in storage for appearance sakes.

A quick subjective determent factor:  does my passenger train in a curve look  like a segmented snake or a series of dominoes? 

After spending many a lunch hour on a bridge watching the Amfleets run by on the NE race track my viewing tastes have been affected.

Eternity is a long time to have been wrong.

Thanks for all the feedback and pictures depicting 072 and 054 performance accommodating a 21" car.  I wish my available table space was greater.  The existing table dimension is 8' by 25' my main curves will need to fit within an 8' width.  I may be able to use 072, but it would be tight taking into account the scenery setting I'd like to use.

I appreciate all your comments and will respond in a few days after I work further with the curves to determine a solution. 


Personally, I'd go with curves as wide as possible.  My 70' passenger cars from MTH look OK on 0-72.  Anything longer would look silly, IMHO.

Can you go with a wider table?  Maybe 9 or 10 feet wide instead?

If not, a 96" wide table can accommodate the 76, 80, 84, and 88 inch curves that you can get from Gargraves/Ross.

When I built my current layout, I thought 0-72 and 0-64 were the bees knees.  The biggest engine I had at the time was a Lionel scale NKP Berkshire.  The next "table" will allow for 0-96 and 0-84 instead.

On a positive note, almost everything looks better running on wide curves.

If wide curves are needed consider going around the wall.  You will get maximum curves.

If I did an island table,  I too would be limited.   but following the walls really opened up the possibilities.

unpretty construction photos Feb 11 007

Using wall supports provides a clear floor and 12' diameter curves

Eternity is a long time to have been wrong.


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Life is full of options. With a 96" table width, a scenery flat along the back wall(s) and some sort of guard at the first four feet from the short wall along the front of the layout you might be able to use O-92 curves.  If you need four to six inch deep scenery along the wall and four inches away from the front edge you are at O-84.  This example assumes a single radius curve - no 'short chute', no easement.  Pay your money and take your pick.  John in Lansing, ILL

Berkshire, thanks but it's the cheap camera and select angles which hide the blems.

Paul, have you considered using larger curves at each end and provide an short over width bump out of the benchwork just to provide support for the little bit extra width needed for the track at that point?

A little trick you could think about would be to use a tight curve for the first 90 degrees of the curve which could be inside a rear corner mountain at each end of the platform and then come out of the portal with a much larger curve for a cosmetic advantage.

If you added  a     \__________/    shaped bump out that could accommodate the bump of the curve.

Some thing like this at the bottom of the photo:


I made some of these for folks a long time ago.  They were featured in OGR around 2003 or 2004 as new products.  They provided the ability to use 072 in a bulb shape on a 4x8.

OGR advertiser Custom Model Railroad Benchwork could make something like this for you,  They are very friendly priced.

Eternity is a long time to have been wrong.


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Bob, thank you.

Paul, some thing to think about, there are at least three things that I would assign priority to when designing a layout:

1.- Adequate curvature.

2.- Turnout placement.

3.- Gradient.

These elements will have a strong influence on how smoothly  (or not) our RRs will run.

Maybe consider adaptable scenery to be the garnishment to our layouts.

Eternity is a long time to have been wrong.

Thank you all for the great suggestions offered here!   I'm going to re-consider my strategy based on the good suggestions here. Eight foot width is my maximum width for the main table.  I'm considering adding an 8 x  8 additional coming off the main table creating a 90 degree "L" off the main table, rather than re-assembling my pool table in that area.  With the addition, my width on one end of the table goes to 16' creating the "L" shaped table.  The majority of the 8 x 8 addition would accommodate an engine house, several side tracks, and basically a rail yard, with a single track loop going around the addition.

I'll do a more detailed drawing of the proposed layout and post it here.  Thanks again to all of you for helpful suggestions!


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