Track standards- parallel track spacing for Maine On2

Parallel track spacing can be a problem for Maine On2 (and other scales) layout builders at the design stage, particularly if they need to shoehorn a design into restricted space, as there is not a lot of information around for guidance, but here’s what we have found.

The NMRA Standard for model railroad parallel track spacing is S-8 which can be viewed here. The general view of the Maine Two Foot modellers is that this standard is not particularly helpful as it depends upon interpretation and interpolation, but still does not give clear results for On2. This was so eloquently put by Yahoo! group member Hilary Smith very many moons ago:-

In my reading so far, I have either not come across spacing discussions or have overlooked them. Looking at NMRA S-8 Track Center Standards for Class II (small four-wheel truck diesels; small steam; old-time, logging, branch line rolling stocking stock) O scale standard gauge puts tangent track at 3.75″ (or 15 scale feet) apart, and for a curve of 41.5″ radius, 3.8125″ apart. For On3, tangents are 2.75″ and for 41.5″ radius, 3.375″, proportionally much wider spacing in curves relative to tangents than in standard gauge. Comparing On3 tangent spacing with standard gauge shows that the track centerlines are a full 1″ or four feet closer together, but on curves only 0.4375″ (or 1.75 feet) closer together. So, are On2 cars no skinnier or longer than their On3 counterparts meaning that On3 spacing standards are a good choice? Or should the centerlines be closer still? Thanks for any observations, experience, or advice.

Hilary Smith,  Northern Virginia

 

The post got two replies;-

Terry Smith: The Maine two foot passenger cars can be longer than was common on three foot gauges, meaning that models of Maine cars “cut the corners” more than the equivalent three foot lines. The controlling dimension is the truck centres. I think that three foot narrow gauge cars are slightly wider in general than two foot, but not sufficiently different to make a difference modelling wise for track centres. ie using the On3 data will be OK for On2.

Trevor Marshall:  
You asked about spacing between tracks on tangents and curves for On2 layouts. I think it’s safe to say, as Terry Smith suggested in his reply, that passenger cars are the critical equipment for curves. Therefore, if you have such a car (SR&RL – not, say, Monson, whose lone passenger car was much shorter), you could do your own testing:

1 – lay a minimum radius curve on a surface on which you can draw with a pencil. You can either spike down a piece of On2 flex, or just a pair of rails, directly onto, say, a 1×6 piece of pine.

2 – put the car on the track.

3 – holding a pencil at each end of the car on the outside of the curve, roll the car along the track so the pencil draws a line on your surface

4 – repeat holding a pencil at the midpoint of the car on the inside of the curve.

5 – measure the offset between the track centerline and each line you’ve drawn.

Note that the pencil line will be slightly offset from the edge of the car – that’s built-in clearance for you. If you don’t yet have a passenger car – or don’t want to use that nicely painted model as a marking device – you could always cut a passenger-car-sized piece from styrene or wood (doesn’t have to be exact, but should be at least as large as the car is, corner to corner), add some bolsters from styrene strip under it at the proper locations, and screw some On2 trucks to it. You could even add pencil holders at each corner and in the middle if you like. Build two of them and you can check clearance on the layout before running your real models through. Heck, even add vertical pieces at the ends and in the center to turn one into a clearance car for bridges, buildings, holes in the backdrop, etc.

That’s curves for you. For straights, I have two standards: For transfer tracks, freight platforms, or other places where cars will be spotted adjacent to each other or adjacent to a structure with the intent that plates be dropped between them for the transfer of goods via hand-trucks or strong backs, I use my widest pieces of equipment to lay the tracks as close together as possible without sideswiping. For other places, I’ve spaced tangent track on 3″ centers. This is way more than the minimum spacing required, but it looks right to me – narrow gauge yards tend to have a spare, open feeling to them, and 3″ spacing allows for an O scale figure to stand between cars on adjacent tracks without getting sideswiped. Remember, the minimum is not always the best.

Hope this helps. – Trevor in Toronto

Some time later, the question was asked again, and this time the replies included references to the Maine Two Foot prototypes and other modellers’ experience.  

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Bob Schlechter: Scaling from the prototype photo above, taken at Bridgton Junction, gives approximately 8′ 7″ to 8′ 9″ as the center to center distance of the two foot trackage to the standard gauge trackage. The photo was taken from the roof of a standard gauge box car looking downward at the trains and trackage giving a good vantage point.

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Bob Schlechter: on my Kennebec Central diorama (above) I used 8 1/2 scale feet center to center. Looks good for prototype spacing but if one is going to do lots of operation and switching you may want it wider to allow for full size fingers to be able to reach in between cars!

 

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Terry Smith: “I used 2½” spacing for straight parallel tracks widening to 2¾” around the curved sections (36” radius) on the Reading iteration of my P&SR (pictured above). I added the extra bit of clearance around the curves because I had a passing loop cum staging tracks that were bent round a 90 degree corner in parallel.
I do not recall having problems with access for manual uncoupling (using a Rix wand for my Kadee’s) or with interfering overhangs/underhangs with the longer rolling stock (coaching stock and Bridgton 34 foot freight stock) or locomotives like the large Forney’s, (B&SR/B&HR #7 & #8), or SR&RL #24 using these values.

 

Bob Harper: I use 3″ spacing on my On3 tracks and 2½” on my On2,  which reflects the difference in width of the real rolling stock – 8′ on the 3′ and 6′ on the 2′ lines. Looking at Franklin on the FAQ’s will show how this looks.

Editor: see the picture above of Bob’s Franklin module where the slight out of focus plus lighting highlight the tracks. To view more pictures of Bob’s Franklin module on another browser page, click here.

Bob Harper continues: Obviously the throw-over of the long On2 coaches is important, but I have found that the critical dimension is the cab on SR&RL #23. This is far wider than anything else (apart from a snow plow?), and my mistake of having the driver leaning out of the side window made clearances even worse! He has since been repositioned.

But another factor to bear in mind is the sense of proportion of the whole scene. Unless we are very fortunate with the space available, we inevitably have to fore-shorten out scenes, and trying to keep a prototypical width while losing the prototypical length can lead to the eye perceiving the track spacing to be too wide. In order to keep the overall scene in proportion, it may be necessary to slightly reduce the track spacing from prototypical standards.

 

Trevor Marshall: I like the generously spaced look of the Maine Two Foot yards, like in the picture below of Bridgton on the B&SR/B&HR;-

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Trevor continues: I’ve used 3″ centers on my On2 layouts. I find it gives that appropriately “NG” look.

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Above is a picture showing Enoch Pond station area under construction in the first iteration of Trevor’s S&PCRR, which captures the spaced out look between the tracks.

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This is a rare overhead shot of the Hebron Pond Slate Company sheds and passenger depot on the second iteration of Trevor’s S&PCRR.

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Trevor continues: – I built a test track board that included both 2′ and standard gauge tracks, side by side, like a transfer yard (illustrated above by the interchange yard at Monson Junction). I lined things up visually – used a standard gauge and 2′ boxcar and double checked my spacing with an engine. I think I left a scale 6″ between the equipment, and raised the 2′ gauge line so that the floors of the cars were level.

What I did NOT do was check the spacing with a 2′ gauge plow. ……..Guess what? They’re a lot wider than other equipment. So, if you can get a plow or mock up the width of one (a block of balsa would do), it’s a good idea for checking clearances.

I think I’d still build the transfer tracks close like I did. Crews will just have to shovel the tracks by hand, or plow when there are no standard gauge cars in the yard.

Editor (18-12-2016): I’ve just found my plans of the Bridgton snow plow #2, which measures 8ft 10ins wide at its maximum – a lot different from the normal 6ft 6in to 6ft 9ins width of Bridgton freight cars and coaches. The model snow plow that Trevor acquired was built from a SRCS kit for SR&RL #513, which measures 8ft 4ins wide at its maximum.

Editor: Here’s a picture of the interchange yard at Snowdon on the second iteration of Trevor’s S&PCRR.

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For more pictures of Trevor’s layouts click here. Well worth a browse!

If you have different suggestions and/or experience and would care to share it with us then please contact us.

 

 

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