Be nice, a redundant question

Well... I'd leave a little more than half.  I have at least one locomotive that overhangs 3.25" from the center rail on O72, my smallest curve.  I left around 4" from fixed obstructions from the center rail.

Cal,

I have an older Williams scale Big Boy. When this locomotive goes around a 072 curve (72" Diameter, 36" radius) the front deck of the locomotive extends 3.25" beyond centerline of the track as measured perpendicular to the centerline of the track to the wall adjacent to the track. I have several large articulated locomotives, and this is the closest to the wall (overhang) I have seen.

Therefore, to be safe, I am not running my trackage closer than 3.5" to an obstruction on the outside of a curve.

Should there be a 21" passenger car on a track to the outside of the Big Boy, it would overhang to the inside 2" from centerline on 072 track and I would need 5.25" inches centerline to centerline on adjacent curves to accommodate a Big Boy on an inside curve and a passenger car on the outside; in this scenario (worst case for my equipment).

Keep in mind a curve with a greater diameter will lessen the overhang in both the locomotive to the outside and passenger car to the inside. I am using flex track and hope by using an easement on my larger curves I can further lessen the overhang.

@CALNNC posted:

can you safely assume if you pick a 4.5 to 6 inch spacing, the outer track from the wall can be half that?

I would say no to 2.25 inches and so close not funny for 3 inches, and the Bigboy and other large overhang engines will hit the wall.

I just measured my layout to confirm I am at 3 inches with Atlas track outer rail from the wall using O-72 curves. It's so close it is scary for the Lionel Legacy Bibgboy and other engines.

Again, I have a number of large MTH Premier and Lionel Visionline and Legacy engines. Having had scrapes into the drywall and paint damage to engines- no less than 3.25 inches would be my advice (note, that is wall to straight parallel section of track after an O-72 curve.

Again, go with the bigger number. Mine is way too close and while I can run everything I own now today, it's just no margin for error.

So agreed, that number might be 3.5 inches or greater.

Vernon said it better  " no less than 3.25 inches would be my advice (note, that is wall to straight parallel section of track after an O-72 curve."   emphasis on measured after the curve when track is parallel to the wall

I suggest one takes some flex track and try different spacings with your equipment. Why guess????

I used a minimum of 4 inches like GRJ said.I also have the Premier Big Boy but I also have Premier Centipedes and GGI both have over hang that are equal to or greater than the Big Boy. I also limited the locomotives to just one main line due to possible interference with over hang on the inner main line and other obstacles that may be in the inner main line.

I think the Centipedes would hit the wall at 3.25...