two or more mainline Gargraves tracks?

One limiting factor is the overhang of the locomotives going into and coming out of the straights.  Articulated engines coming out of an 0-160 curve won't need as much distance between tracks as the same engine coming out of an O-72 curve.   John in Lansing, ILL

My layout is 27' X 12'. On the upper level I have an older double track Miami Valley wooden bridge. Center to center is 3 and 1/2 inches through the bridge. Extending out from the bridge I gradually transitioned the track centers out to the curves at the corners of the layout where I used 0-89 and 0-96 curves. You need good spacing going into the curves and in the curves to handle the overhang on the larger scale cars and engines......Paul

Perfect straight.  3.5 inches.  Just remember if these are yard/staging tracks and you have to couple/uncouple cars in lines adjacent to one another, the space is to close.

NOTE:  Prototype Space main-lines 14 feet translation O scale 3.5 inches.  

My layout is all gargraves track and turnouts. I elected for 4-1/4 spacing between center rails on the mains. Why, this is the distance when you use opposing 100" turnouts together for smoother higher speed track changes. Note- you could go down to 4" with no turnouts on the straights with no issue.  On the curves recommend at least 5" between center rails to allow for longer cars and articulated engines. Much more if using less than 80 or 72 curves.

Dennis:

Take a look at the Ross 4 way yard turnout. I would think you do not want to get the track center to center any closer than that.

However tracks as close as those in the Ross Yard turnout are strictly meant for straight runs so as Rattler said once you hit a curve the center to center distance is dictated by the radius of the curve and the swing out of you locomotives and big cars.

Unfortunately I cannot think of any way one can swing both tracks out in preparation for a curve since no matter what you do there is one point where the inside curve will intersect with a straight from the outside track.

Model structures is right. I just installed a Ross 4 way switch last year and I have the tracks as close as you could get. But with the switch you have to allow for the curved track to the straight because coming into the switch engines or rolling stock would hit. Pic of mine for my freight yard.........Paul

3-1/2" on straights roughly translates into 4-1/2 feet  between outside rails; Unless actual cars grow to more than a 2 foot  (1/2" scale) overhang off the wheels, that spacing is OK. If you plan on using wider cars you might want a bit more.

For curves I created an acrylic car  with a rectangular 1/4" base that is the size of the biggest car I have. I then added truck-wheels to the base at the same spacing. At the outside corners of the base and the midsections I added vertical plastic tubes that I could insert pencils or markers. As I run the car on the track the markers trace out the furthest distances on the layout marking the cars overhangs. I use the marked layout to place the curved track.

Thanks for asking this question!  

I have a short yard area where the tracks (Gargraves) are spaced 3.5" apart.  It seems to work fine.  However, more than one visitor has commented, in effect 'Whoa!  Boy are those two tracks REALLY close!'

So, I began to think about altering their spacing to a more typical/generous 4.0"to 4.5" spacing.  

But, now I'm asking myself 'Why?'.  It works.  I haven't had an operational problem.  

I think I'll move this down farther on ye olde bucket list.....

KD

I always use 4" spacing, straight and curves (072 minimum). Works for me, though there are a few pieces on the roster that can't meet on a couple curves. I agree, straights could go to 3.5" centers.

Big_Boy_4005 posted:

I always use 4" spacing, straight and curves (072 minimum). Works for me, though there are a few pieces on the roster that can't meet on a couple curves. I agree, straights could go to 3.5" centers.

Eliot, I'm shocked you get away with 4" spacing on curves!  Our club layout used 4.5" spacing, and a number of trains meet on the adjacent tracks, and not in a good way!  A couple months ago, I wiped out a passenger train with my VL-BB, that sucker was TOAST!   BTW, those are around O90 curves, so O72 would really be a problem IMO.  I'd consider 5" spacing for curves.

3.5"

Well John, I only have a couple large steamers, and the Big Boy will never run because there are too many clearance issues beyond the curves. It's a shelf queen. The Challenger will go almost everywhere, but will only be used on limited routes to pull the new Excursion set.

Keep in mind my layout isn't a club setting where anyone can bring anything to run. As far as widening the centers on the curves, that train has left the station. Remember, this layout was designed back in the late 90's, before any of the monster pieces that demand those clearances were even thought of.

I have paid more attention as of late when I was laying track. I even rebuilt the big helix supports to allow the 89' auto racks to clear. I still have a little work left on that project, as I wasn't able to move the supports on the outside of the bottom two turns. I have to come up with a way to shave the corners off 32 supports so the ladders clear.

I would agree with 3.5", but only in a yard. It is tight but it works. That is because a) only one train is moving at a time and, b) it is/should be moving slowly.

Remember, some of these trains have a tendency to rock depending on speed, weight, etc. On two parallel mains with two trains travelling in opposite directions at normal speed?? I don't know?? Personally, I would not go less that 4" on mainlines.

Big_Boy_4005 posted:

Keep in mind my layout isn't a club setting where anyone can bring anything to run. As far as widening the centers on the curves, that train has left the station. Remember, this layout was designed back in the late 90's, before any of the monster pieces that demand those clearances were even thought of.

Right, but I was really targeting my comments to the guy(s) that are still trying to determine the correct spacing. IMO, for curves to run most anything on adjacent tracks, you should plan on 5" center-to-center spacing. I have no problem with closer spacing on straight tracks. The VL-BB happens to have an extreme overhang, but the Lionel Legacy Y3 also hits 21" passenger cars on the 4.5 spacing on the same curves. I'm assuming that my Allegheny or the Challenger would have the same issue.

These unmodified Ross switches appear to facilitate 4" track centers. Wider than 4.5" just doesn't look so good IMO (especially on straights) and is only needed for large equipment with not-so-wide curves. O72 curves are really not very wide for long articulated locos and scale length passenger cars, if you care about good appearance on curves for a scale layout. For "traditional" O-gauge we bend the rules a lot more and call it good enough, so we can have layouts in smaller spaces.

It would be really helpful if there was a table for larger cars and locos giving the overhang on the inside and outside of curves (like for O72, at least). Then all you need to do is take the largest numbers for inside and outside overhang for your equipment, add a margin for safe clearance, and you know the minimum feasible track centers on those curves for sure.