Track Distances

Check the archives. I made blocks with premeasured gaps to place over the rails.

Some are 3.5" from center rail, some are 4" and some are 5". Curves require more space. Some big steam engines have big swings. 

Marshallangelo

I have my track set up 4"  from center rail to center rail. I run some big train nothing touches and it also clears the inside of Lionel 2 track signal bridges. At my club on Long Island we have a few kit-bashed tunnel portals.  The standard portals should be ok so long as you have them on straight track. If you position them on or near curves you will need to trim something off the sides.  Feel free to visit the club or website is below with open house dates on e-mail me from my profile and would be glad to arrange an insiders tour.  Hope this helps :-)

Thanks guys, I kind of figured it out as I kept playing around with the track and I came to the conclusion about putting the portal (which is a standard type) on straight track and I've noticed the differences as curves go in and out at different locations.  I was getting ready to buy an NMRA O scale gauge but I didn't think after some investigating that it would solve my problem.  I'll go down to the layout and observe what I have going on. - Thanks again - MARSHELANGELO

A lot of the spacing depends on switches and where they are - crossovers set you straights - 4" center rail to center rail is good - numbered switches get that - you will be wider with radius switches like O72

On the curves, Atlas O81 and O72 are a 9" difference in diameter or 4.5" radius center to center naturally. You can stagger the entry (start points) of the first curve to create a larger or smaller difference.

Take a piece of 1/2" wood and make a saw cut in the end with the desired center rail to center rail difference - then just lay that edge on the track as a guide

Trim tunnel portals to fit the track and trains

5" or 5.5" centers give you worry free spacing

Thank you MOONMAN

The tracks must be exactly parallel at least one car-length (say 21 to 24 inches) before entering the tunnel - with center-rail spacing at least 4-1/2 inches for any track diameter less than O-72. Check the width of the double tunnel portal opening to see if it is sufficient, allowing:

1) At least 4-1/2 inches center-rail spacing

2) 3 inches ballast width each track

3) 1/4 inch clearance each side of portal (times 2 for both sides equals 1/2 inch)

4) Total equals 8 inches

Set up the tracks and check clearances with your longest locomotives and cars before permanent positioning.

MELGAR

Appreciate the info MELGAR.

Here are some of the blocks.

L.I.TRAIN posted:

I have my track set up 4"  from center rail to center rail. I run some big train nothing touches and it also clears the inside of Lionel 2 track signal bridges.

I'm having a difficult time with 4" spacing center-to-center and running "big stuff".  My VL-BB has a bit more than a 3" overhang from the centerline on O72 curves, and the MTH Premier BB has about 1/4" more than the VL-BB.  On 5" spaced O99 curves at our club, the VL-BB cleaned the 89' auto carriers off the outside curve coming the other way.  4" on curves seems way too tight to me for anything articulated.

gunrunnerjohn posted:

L.I.TRAIN posted:

I have my track set up 4"  from center rail to center rail. I run some big train nothing touches and it also clears the inside of Lionel 2 track signal bridges.

I'm having a difficult time with 4" spacing center-to-center and running "big stuff".  My VL-BB has a bit more than a 3" overhang from the centerline on O72 curves, and the MTH Premier BB has about 1/4" more than the VL-BB.  On 5" spaced O99 curves at our club, the VL-BB cleaned the 89' auto carriers off the outside curve coming the other way.  4" on curves seems way too tight to me for anything articulated.

Couldn't agree more. Lionel 21" passenger cars can create problems at 4.5" and I won't even go into the MTH DDA40X that clobbers everything on 4.5" curves.

The Atlas track system is designed to work on 4.5" center-to-center spacing.  Both the #5s and #7,5 turnouts will maintain that spacing when setup as a crossover.

The larger the curve diameter the critical the track spacing.  The lesser the overhang.

My current layout uses O81 and O90 on the dual mainlines.  O72 is used elsewhere in the yard and sidings.  The redesign will use O90 and O99 (not enough room for O108).

Atlas and MTH Scaletrax numbered turnouts produce 4.5" spacing.  Ross tracks are spaced at 4".  Gargraves O100 switches create a 4.25" spacing.

So, unless you do something to squeeze the track together you'll have a spacing of 4" to 4.5".

Jan

Interested to know how you plan to alter the Atlas designed 4.5" spacing to something less. I can only see using flex track.

John if your curves are “eased” (gradually tightening spiral), the overhang might be a bit less.  The locos will also look much better entering the curves.  I’m interested in max action, so I have to set the lines as close together as possible.  As a result, I’ve pretty much banned articulateds from my layout.  There’s really no good solution. 😔

To widen the Atlas 4.5" designed spacing, I added a 4-tie-length straight piece after the last parallel full straight on the outside (054) oval.  The space center-rail-to-center-rail between the 045 and 054 is now 6".

Ted S posted:

 I’m interested in max action, so I’ve pretty much banned articulateds from my layout. 

If I ban articulated locomotives, I'll have a bunch of shelf queens!

You have a lot of queens on that set of shelves you posted earlier. Can't wait to see some of them circling that new layout!

You and me both John!

As I play around with the track, I've also discovered that if I extend the tunnel portal on my uncompleted train tunnel the Vision Line Challenger and the SF Gold Bonnet PA with 21" passenger cars don't have a problem with entering the tunnel as of yet.  Still a lot of building and track laying to do.