Clearences

[Anonymous]

I'm ripping up my layout after a year of designing ang running it.
Not happy with it. Gonna build a new one. And am goin to have
some rail crossing over another. What would be the minimum
clearence I could get away with for realistic operation. I'm doin
late 40's steam and early Dieseland hopefully laser cut structures.[bow]

[Adelie]

The NMRA standards for all scales can be found at:
http://www.nmra.org/standards/s-7.html

If you have existing rolling stock you are going to migrate over to the new empire, measure it to confirm that the NMRA minimum is adequate. I would think you'd be okay in the late 40's era.

[dehusman]

When designing it just remember that the clearance is from the top of the rail on the lower track to the bottom of the supports for the upper track. The top of the rail for the upper track is higher by the thickness of the bridge. If you want 4 inch separation and your bridge is 1.5 in thick then the upper track has to be at 5.5 in elevation.

Dave H.

[selector]

The general rule that most of us modelers agree to, just to get you oriented, (I assume HO?) is 3.5" (three and-a-half inches). That is measured from the top of the lower track rails to the lowest obstruction that can be encountered by any of your current, AND FUTURE, locos and rolling stock.

Some go higher, just to be safe, but 3 1/2" is usually lots.

[bogp40]

Try not to use more than 4 1/2"(clearance not rail to rail), most castings/ molds for abutments are generally only 4". Some deviation for exteme height may be necessary for your track plan, these can be scratch built. I keep the min clearance to 3 1/2". Be careful with portals especially on a curve, double stacks and some double decked passenger equipment need additional clearance on the inside of the radius.
Don't ask how I found this outBob K.

[MisterBeasley]

Unless you have a very long distance to make up the grade, remember that there is a trade-off between clearance and slope. You want as much clearance as possible (up to a point) but you also want gentle grades.

One option, since you're starting from scratch, is to take the lower track down a grade, and the upper track up a grade, but that way each of them only has to be half as severe.

[Anonymous]

We're working on a sort of modified dog-bone-in-a-dog-bone layout, and have a set of curves that come out of tunnels. As they are single tracks, I thought we could use single track portals.

My design partner (my 6 yr old) of course wants to run trains, so we ran them one night after the foam & plaster was done, but before the scenery or track was done (and the portals weren't glued inplace yet either).

Glad I have a son that wanted to "try out the layout".... our long (passenger) cars all clipped the sides of the portals...so we migrated to the double track portals.... and I learned (since this is our first layout) the importance of "dry runs" on your layout during the building process.

[bogp40]

QUOTE: Originally posted by malexenko

We're working on a sort of modified dog-bone-in-a-dog-bone layout, and have a set of curves that come out of tunnels. As they are single tracks, I thought we could use single track portals.

My design partner (my 6 yr old) of course wants to run trains, so we ran them one night after the foam & plaster was done, but before the scenery or track was done (and the portals weren't glued inplace yet either).

Glad I have a son that wanted to "try out the layout".... our long (passenger) cars all clipped the sides of the portals...so we migrated to the double track portals.... and I learned (since this is our first layout) the importance of "dry runs" on your layout during the building process.

If your portals end up looking much too wide, consider cutting the portal and remove the appropriate amount for clearance. This can be done by cutting a double or cutting two singles. The latter even though needing two portals usually works better, the keystone end up wider not lost altogether as shortening a double.
Bob K.

[selector]

I have three tunnel portals on my layout, and every one lies over a radius (22"). I just like seeing curved track exit a tunnel. I tested each one with a loco and pax car to ensure that they cleared well. Then, I marked the footprint of the portal so that I could reposition it when the time came to cement it into place..after the entire track plan was itself confirmed for alignment and grade.