clearance

although I have no idea why this page is so hard to find if you hit the splash page and look for it. You can read about the standards, then the RP's. Most is straight forward and you shouldn't have problems. Just remember not to cheat on the tolerance's to make things 'fit'...

todh

Good morning CT;

It is indeed hard to spot. The NMRA Home Page is a busy page because of so many things competing for attention.

Cheers, John

Good morning JE;

Typical track separation is 15 feet 'on center' which works out to about

2-1/16" in HO scaling. Conventional wisdom uses a 2" rail spacing.

The radii of curves for manufactured track is typically 15" to 22". Flex track can be used if you're making broader curves or simply minimizing the number of joints.

If you're using longer cars, the spacing must be wider (eg 2-1/4") in turns to avoid sideswiping cars on adjacent tracks. If you're cramped for space, my suggestion is avoid using longer stock on curves whose radii are

15".

The NMRA

Standards & Conformance guidelines are a bit cryptic, but are useful and provide consistency for hobbyists. Best of luck on your pike.

Cheers, John

Refer to NMRA Standard S-8 ("Track Centers"):

The preferred minimum spacing between straight tracks is 2 1/16" (modelers often simplify that to 2") for clearance for your fingers to allow easy handling and coupling of cars. If you don't need to get your fingers between the tracks, NMRA S-8 recommend 1 13/16" minimum between tracks.

Curves require wider track spacing because of overhanging equipment. To use NMRA S-8, select your class of equipment you plan on operating on your layout from the descriptions at the top of the table (class II, I, Ia), go down to the "HO" section of the table and find the minimum radius you plan on using on your layout. The table gives the recommended minimum track spacing for that combination of equipment and curvature. But you should still keep the 2 1/16" minimum in mind if you need finger clearance between the tracks, regardless of the curvature of your track.

[A side note on track radius - If you're not sure what radius you may be using, NMRA recommended Practice RP-11 ("Curvature and Rolling Stock") has some guidance: Select the class of equipment that you plan on operating, and the table gives the recommended minimum radius for that type of equipment.]

__________ Mark Mathu The Green Bay Route:

"I started out with nothing and I still have most of it."

"Track planning for Realistic Operation" by John Armstrong is a great book if you are in the layout planning stages. Also the NMRA track gage is very helpful. Are you thinking of a 4 * 8 table or an around the walls layout?

David Starr

---------------------------------------------------------------------------------------------------------------- I agree. My copy is almost worn out from using it over the years. Every model railroader should have "Track Planning for Realistic Operation"...

This book is 32% off list and there is free shipping on orders over $25.

Bill Bill's Railroad Empire N Scale Model Railroad:

History of N Scale: Railroad Bookstore: to 1,100 sites:

I don't like the fact that the NMRA track gauge doesn't adjust for track radius.

Only 3-point track gauges will "adjust for radius" - and they do so automatically. You could use a stepped two-point gauge, but why bother?

The NMRA track gauge is also a clearance gauge - clearance was OP's concern.

The NMRA gauge also gauges wheels, check gauge, and flangeways.

FWIW, I've used it as a template to make a clearance gauge out of 3/4 ply, which is thick enough to sit on the track by itself. Very handy. On curves, I gauge the extra clearance needed by eye. I wasn't too precise

- the gauge is slightly larger than the NMRA gauge, which is just fine. Clearance diagrams are of use only in the tightest of spaces, which prototype railroads avoid as much as possible. The only really tight clearances I've ever seen were where sidings entered buildings. I have a sign from the now defunct London and Port Stanley Railway warning switchmen about tight clearance at a building entrance. The L&PS ran from London Ontario to Port Stanley on Lake Erie.

HTH