I am so new ...

[Anonymous]

... I don't even own track yet!  but I have a table (4' x 8') built and ready.

I am still deciding on a track layout to use.  I am using Atlas' free track layout planning software to do the design and have many questions.

My biggest roadblock right now is, finding how much clearance I should leave in a tunnel for the top of the train to clear.  With that, I will know how high I have to raise my top rail and figure out my inclines.

Any suggestion on clearance?

 

johncjr

[Beach Bill]

The National Model RR Association (NMRA) standards gauge allows right at 3" of clearance from the top of the rail.   This NMRA standards gauge would be a good purchase for you, as it will also help you check your cars and locomotives if they have tracking problems, allow you to check if that factory-produced track is correctly spaced, and also help with establishing clearances for loading docks along the track.

 Welcome aboard!

Bill

[Johnnny_reb]

for clearance you need about a half inch from the top of your tallest piece of rolling stock. Most times that would be about 3-inches in HO scale.

[SpaceMouse]

A few things.

Read my Beginner's Guide clickable from my signature.

Check out the recent 4 x 8 contest and see what can be done on a 4 x 8.  2007 4 x 8 design contest

Check out the discussion on designing with RTS. 
http://cs.trains.com/forums/1388100/ShowPost.aspx

Last, you can get an NMRA guage that will help you make sure you have clearances. You can also get the exact specs, from the NMRA website. I believe www.nmra.org.

 

[pcarrell]

If you tell us the scale you're modeling in it'll be a lot easier for us to answer.

[Anonymous]

Thank you for the great answers and suggestions.

I was bad for not providing the scale.  It is in fact HO.

Thnx

 

johncjr

[Phoebe Vet]

Go to the hobby shop and buy a tunnel portal.

Use it for a template.

[loathar]

http://www.nmra.org/standards/sandrp/consist.html

Everything you need to know about model train standards.

[wjstix]

BTW if you're talking about how high you need to raise the track to have one track go over another one, the answer is DON'T if you're building a small layout. You'll end up with a steep grade that will severely limit the amount your engines can pull. Plus to get it to work, you'll need to start climbing as soon as your track goes under the other, so all your track will be going up to say a bridge, then going down below the bridge, with very little level track.

If you want to add some cosmetic grades of 2% or so to have tracks of different elevations that's fine, but I wouldn't try an 'over and under' track design in HO on a 4' x 8' layout....unless you're modelling a logging line or something where steep grades are part of the deal of course!!

[Anonymous]

BTW if you're talking about how high you need to raise the track to have one track go over another one, the answer is DON'T if you're building a small layout. You'll end up with a steep grade that will severely limit the amount your engines can pull. Plus to get it to work, you'll need to start climbing as soon as your track goes under the other, so all your track will be going up to say a bridge, then going down below the bridge, with very little level track.

If you want to add some cosmetic grades of 2% or so to have tracks of different elevations that's fine, but I wouldn't try an 'over and under' track design in HO on a 4' x 8' layout....unless you're modelling a logging line or something where steep grades are part of the deal of course!!

Thank you for the advice.  An over/under non-logging is exactly what I was planning and in planning, did notice that the only level track I had was through the tunnel and my rail yard.  Due to your comment, I think I will re-think my plan.

Thank you once again.

 John C

[R. T. POTEET]

johncjr, welcome to the forum. There is a thread up in the General Discussion section about "THE WORLD'S GREATEST HOBBY"; take it from R. T. POTEET, this is indeed "THE WORLD'S GREATEST HOBBY"

Not wanting to confuse you but I must take a minor exception the the answer tendered up by wjstix relating to an over-under loop; I would advance that the answer is less a firm DON'T and more of a DON'T IF YOU CAN AVOID IT. On a 4X8 layout about the only possible utilization for an over-under crossing is in the design of a Figure-8 and these look very toylike in operation. Still it can be done and surprisingly the gradient is less than might be expected.

About the only radius you can fit into your 4 foot width leaving a three inch scenery buffer between the edge of ties and your table edge is going to be about 20.5 inches. That will render out to a 129 inch circumferance circle; two thirds of that circle - 120º will give you a distance of 86 inches. The tails of this partial circumferance are each going to be about 27 inches in length. Add 86+27+27 gives a total distance for one track to climb above the other track as 140 inches. To climb the requisite 3 inches in 140 inches requires a gradient of 2.14% which is less than the maximum gradient on the first transcontinental railroad. That gradient is stiff but not prohibitive except that, coupled with the friction your rolling stock will encounter on your 20.5 inch radius curve. will probably cut your effective train length by 50% or more.

[rogerhensley]

Try the NMRA Beginner's Pages for a whole lot of good advice.

 

http://www.nmra.org/beginner/