minimum height for n-scale bridges/overpass

[Anonymous]

Thanks for all the newbie help already...one more....
[;)]

If we are building a layout where the track will cross over itself (like a bridge), what's the ecommended height of a riser for n-scale?... meaning, what height between the lower track and the bottom of the upper track.

thanks again.

[dave9999]

In HO, you would generally try to leave 4 inches of clearance. I'm not in N scale,
but would assume 2 inches would be a good rule. This is clearance... from the
top of the rail head to anything above the rail. Dave

Again I'm not in N scale, so someone may need to correct this.

[MAbruce]

Most N-scale stock bridge abutments range from 2 1/2 inches to 3 inches. I'd say 3 inches would be safe (especially for modern equipment with higher clearances).

[egmurphy]

NMRA Standards Gauge for N scale has a 1-5/8" vertical clearance dimension. I've got one overpass that has 1-7/8" and seems to clear everything I've got with room to spare.

If you plan on running a lot of the modern double stack containers you might want to see how high they are as I don't run them.

The more clearance you build in means you need to have more horizontal run to keep the same maximum grade.

iirc you are trying to build a small layout. Sometimes you just have work a compromise between what you'd like to have, and the realistic limits of minimum radius, max grade, and modern day equipment sizes.


Regards

Ed

[rrinker]

John Armstrong in "Track Planning for Realistic Operation" lists 2" as 'normal' for N scale, and a bit over 1.5" as 'minimal' His usual definitions are that you can get by with minimal if you make things like the bridge deck unrealitically thin - after all we don't need the strength like the real thing. But if you can view the bridge from the side, it will be too obvious. By using the 'normal' clearance, you have plenty of room to build a proper scale bridge deck.

--Randy

[egmurphy]

Randy,

We may be talking slightly different definitions. You seem to be referring to difference in elevation from top of one rail to top of the other rail. Otherwise it wouldn't matter how thick the bridge was.

The dimensions I was giving were "clear" dimension from the top of the rail to the bottom of whatever (beam, bridge) .

I suspect that both recommendations are valid, I just wanted to make that distinction between the two to avoid confusion.

Regards

Ed