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Track Spacing Questions

Larry a hesitant newbie to the hobby has these three questions to ask:

“I don’t think I’ll ever be a serious model railroader, but my son wants us both to work on a project together. For some reason, he thinks I need a new interest to keep me mentally and physically active. He’s probably right as usual so I’ll give it a good go.

My (our) HO layout will consist of two 4ft x 8ft panels joined with a 4ft x 4ft panel to form a U shape. This will give me (us) space to move around.

My questions – 1. How close to the base edge can the closest track be? 2. What is the recommended separation between parallel tracks from the outside rail of the first track to the inside rail of the track running parallel with it? 3. Should I (we) allow extra separation on the curves, and if so, how much?”

Comments below.

9 Responses to Track Spacing Questions

  • Dwight Campbell says:

    Hi Larry,
    To answer your first question, I use what I call “FLOP” space. I model in N gauge and use an inch and a half as my minimum. Nscale engines are about an inch tall so if one”flops” on it’s side next to the track it measures an inch – add a half so it won’t fall off the table. HO scale will probably run about two and a half inches but to feel comfortable lay an engine on it’s side next to a piece of track at the table edge and get the spacing that makes you fel comfortable about not finding things on the floor. Question 2 and 3 can be best answered by pointing you to the NMRA.ORG website. This is the National Model Railroading Association website. There is a ton of technical info but if you go to the Recommended Practices, (RP), section it will give you track spacings, tangents, and the like.

  • Matt Jackson says:

    As a practical matter, a “person” needs a minimum of three feet for an aisle between to solid objects. That translates into 13 feet between track center lines or 3 1/4″ In O scale, That’s about 1 5/8″ in H.O. That said, you need room for your fingers and on curves you need to increase that to allow for equipment to swing out (and swing in on longer equipment). There’s a book “101 Track Plans” by Kalmbach (Model Railroader) that gives recommended spacing for various curve sizes. Off the top of my head, sharp curves (18″ radius) require about 2.5″ of spacing; Conventional/medium curves require about 2.25″ and Broad curves (30″ radius and above) require about 2″ spacing. That all goes out the window when you involved large articulated steam running on the inside curve with a passenger car on the outside.

    Hope this helps.

  • Graeme David Wilson says:

    if there is any POINTS, TURNOUTs in place this will get you started to run parallel

  • Jeff Morrow says:

    I use a distance of 3″ to 5″ from the table edge for my outermost track. This gives enough room to keep things falling off the table (usually), plus room for scenery and background buildings. As far as track spacing, there is a lot of information on the NMRA.ORG website and in many of the model railroader forums online. This can get pretty technical, although accurate. I use a general rule of thumb of about 1.9 ” center line to center line on straight sections of open runs and about 2.1″ – 2.5″ center line to center line for yard track, depending on what is happening in the yard. Remember, when planning your track layout to take into account the buildings and infrastructure you will need, things like signals, huts, trackside details, etc.

    Curves are another matter. You will need to have more separation on curves depending on both the inner and outer curve radii, the cant of the track around the curves and the types of rolling stock you plan to run. Referring to the NMRA documentation will give you all the spacing information, but, as a first approximation, you could put down some track (not fastened) and try a few cars passing each other to get an idea of what works. You also need to think about these clearances for things like bridge and tunnel entries.

  • Mike Berke says:

    Hi Larry!
    1st off, happy new year!! Hope it’s healthy and filled with happy railroading!!
    I have kept the distance from the edge of the table surface to the end of the tie strip at 1 inch. I keep the distance between track center lines at 2 inches in straightaways to 2.5 inches on curves, where the radius minimum is 18 inches. This has worked well for me for quire some time. Hope it works for you, too.


    For track spacing, I use the inexpensive PECO SL-36 way gauge; a thin flat red plastic strip that includes two tabs on each side that fit into HO/OO track. Use the closer spacing on one side for spacing of 2x parallel tracks, and the wider spacing on the other side for curves. From memory, the tab spacing provide either a 2″ or 2.5″ spacings. I usually allow minimum 3″ minimum board edge to track centre around the perimeter, but would suggest banking the curved tracks ( known as Super Elevation), to reduce possibility of trains shooting off at the corners.

  • phil+johnson says:

    2″ centerline to centerline in straight. 2.25-2.5″ centerline to centerline n curves depending on radius. The sharper the curve the greater the centerline distance

  • Mark Phillips says:

    If you are using set track, the radius of each of the curves you are using will set the distance between each set of rails – if outside track uses 4th radius curves, 3rd radius curves on the inside lane will then dictate the spacing of the straights. Similarly if you were to add another loop, using 2nd radius curves would give you the spacing for the straights.

  • Larry (LAZ) says:

    I’m blown away by all the helpful advice. A great community. Thank you to all who pitched in. LAZ.

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