Track spacing in yards and mainline


Just beginning the design and build of a HO scale railroad layout.  Some basic questions I do not see much discussion about. 

When building a yard, how wide should the track spacing be?  It seems to me 2 inch spacing center to center is wide enough to do basic yard operations or disconnect a car.  The other part of that question is spacing if you are running a two track mainline.  Again, 2 inch spacing appears to be sufficient except on curves where 2.5 inches seems enough based on running the 89' auto carriers and other long cars.  But I have not found any discussion about what is a recommended spacing for either case.  Curves there is discussion on how to figure that out.  WHich is how I came up with the 2.5 inch spacing based on actually setting up the curves and measuring the cars as they negotiate the curves.

Second question is how often would a rerailer track be necessary on a layout?  Have never seen any discussion on that topic.  But I assume there are some recommended locations for a rerailer.  Any suggestions from anyone.

dfandrews's picture

right on


You are right on with 2" mainline spacing.  That is fairly standard in HO.  Curve spacing is determined in actual conditions with your intended rolling stock, exactly as you have done.

I tried yard spacing of 1-3/4" and 1-7/8".  It looks OK, but both are too narrow for my fingers.  I settled on 1-7/8", knowing that any rerailing or adding rolling stock to the layout has to be done on the yard lead or drill track.

I installed rerailers at the ends of a lift bridge across my door way, but they have not been necessary.

So, I would say, rerailers can be used at staging/fiddle yards where you're moving rolling stock from storage cabinets to the track, using the ol' "0-5-0 switcher".


Rincon Pacific Rwy, 1960.  HO scale std. gauge - interchange with SP.


DKRickman's picture

2" works for me

First off, the NMRA has a handy chart of suggested spacings for various length equipment on a variety of curves, found at

Second, I use 2" on all my tracks.  For one thing, it's easy to lay out and it looks decent.  For another, a lot of commercial turnouts naturally line up things like yard ladders on 2" centers.  It's easier than having to trim or shim every piece.

Ken Rickman

Danville & Western HO modeler and web historian


NMRA Standard S-8 shows that track centers for tangent track could be as close as 1 13/16". 2" seems to work for us fat-fingered car handlers.  Centers on curves vary, based on the type and era of equipment run, and radius.  For instance, it shows 2 1/2 " minimum centers for 32" radius when using the most modern equipment with their larger profiles and greater lengths.  For an older or smaller set of equipment operating on 18", it recommends 2 3/16".  If you run broader minimum radius curves the centers can become closer, or as little as 2 3/8" on a 40" curve for the large modern equipment..

Jurgen Kleylein's picture

in 12 inch to the foot scale

If you want prototype specs, yard tracks are usually laid out with at least 13 foot centers, and mainline is at least 15 foot.  I never make allowances for fingers between cars in yard tracks, just keep it to scale.


HO Deutsche Bundesbahn circa 1970

Visit the HO Sudbury Division at

The preceding message may not conform to NMRA recommended practices.


Thanks for the comments and suggestions.  Sure I will have many other questions as we pursue this exciting adventure in model railroading.  I will put up an overview of the total layout and what we are looking at later for some constructive comments/criticism.  This is a long term project for us as we look to head into retirement.  Worked long and hard my whole life for others, now I can take that same dedication to put towards what I want to accomplish.  Thanks for all.

jrbernier's picture

  I use 2" spacing on

  I use 2" spacing on straight track, and  2 1/2" spacing on curves(30" radius).  This handles all full length passenger cars and  auto racks(HO scale).  I have never tried running an articulated steam engine on the inner track(I suspect the overhang of the smoke box might be a problem.

  On the prototype, I have seen 12' track centers on curves(old MILW 'Harts' yard in SE Mpls).  Clearance for a switchman hanging on a car was quite tight there.  Any 'new' construction must be a minimum of 15' track centers(government regulation).  This has been in effect since the 60's, IIRC.  UP is using 20' track centers on new construction, and BNSF is using 30' track centers.  I was told that with the 30' track centers, track workers on mechanized track equipment do not have to 'dis-mount' from their equipment while a train passes by them on the other track at restricted speed.  The DM&E has a new siding at Janesville, MN - It is what looks like 25'-30' track centers as well.  This siding has a lead to a large ethanol plant, and they build unit ethanol trains on this siding.  I suppose safety of trainman walking the unit train and lacing up the air hoses is better with this wide track spacing.


Modeling BNSF in SW Wisconsin


I use rerailers on storage tracks that are hard to reach.  I don't have any out in the open.   I use hidden or behind the scene tracks to add/remove cars from the layout.  I put one in these areas as well.



MILW199's picture

Track spacing

A lot of older tracks were laid out with 13 foot centers.  As rolling stock has gotten bigger, the space available for a man on the side of a car has shrunk, to the point that riding on the side isn't really safe anymore. 

I believe newer FRA regs state that with 25 foot centers, a track crew can work on a track and not need to be interrupted when a train comes by on the adjacent track.  Otherwise, a train comes up, and work stops while the train goes by. 

For HO scale, I generally use 2" on straight, more on curves as needed.  Actually being able to use the model yard trumps aesthetic concerns, I feel. 

Mike  WSOR engineer  "Safety First (unless it costs money)"

JamesS's picture


Rerailers in tunnels are a smart move.



Milwaukee  to  Lac du Flambeau

17' x 20'  HO with RailPro


Track spacing depends on era, the more modern the construction the wider the spacing.

Yards could be down to 12 ft spacing, mains to 13 ft for track built in the steam era.  Track built since then will have 15 ft or so spacing on the main track.  If its modern  track, brand new in the last 10-20 years, the main track spacing could be 25 ft .

If you have track workers on an adjacent track that is less than 25 ft spacing, Federal regulations require trains passing the workers to reduce speed, if the tracks are 25 ft or more apart, there are no speed restrictions.

Since the longest car I operate is a 70 ft passenger car, I use 2" track centers on my entire layout.

The only place I use rerailers is as connectors between removeable staging yard sections.  I you NEED rerailers, then you have bigger problems than where to put them.

Dave Husman

Modeling the Wilmington & Northern Branch in 1900-1905

Iron men and wooden cars.

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