How high ?

[eja]

I am planning to install a bridge over one of my tracks.  I would like to assure that I have enough clearance for a double stack train, but currently I don't have any such cars.

Would someone who does please measure the height of one (from the railhead to the top of the highest container) and post the results here.


Thanks for your help.

[railnerd]

You can always use this info:

    http://www.nmra.org/sites/default/files/standards/sandrp/pdf/s-7_2012.02.pdf

-Dave

[Baronjutter]

I run double stacks and find 2" is a nice round rule of thumb number.  1.85" or so inches would probably do but some well cars ride higher than others and it's nice to not have to worry.  On my old layout I did the absolute minimum for my kato double stacks and then found some atlas cars rode about 1mm higher.  2" will be totally safe and nice.

[ryan_wilkerson]

I just measured a pair of Walthers 48' containers (some of the taller ones) in a Kato Maxi-IV car and it's 1.83" from the top of the rail so you should be fine with 2". As a teenager I made the mistake of measuring from the plywood to the underside of the bridge. Then I laid the cork and track and learned from my mistake!

[ScrewySqrl]

just to make it even easier:  a 2% grade is exactly 4 feet per inch of rise, so to get 2" at 2% you need 8 feet of track to get there.

[nkalanaga]

I'd also go with two inches, remembering Ryan's advice to measure from the railhead, not the plywood!

[eric220]

just to make it even easier:  a 2% grade is exactly 4 feet per inch of rise, so to get 2" at 2% you need 8 feet of track to get there.

Almost, but not quite.  2% is 1" vertical per 50" linear.  Four feet is 48".  Close, but no cigar.

[Flagler]

The Kato piers and Bridge are around 2 3/16",but this might allow for the Unitrack roadbed.I use a woodland  scenic starter grade section on 2" of foam to bring it up to the Kato pier height

[Flagler]

I like to get really High
 

[Bangorboy]

One consideration about that grade length --

If you raise the upper track only two inches above the lower track, you won't have two inches of clearance, your clearance will be minus the thickness of the track, ties, roadbed and supporting material (Homasote, plywood, etc) holding up the upper train.

A run of 8' 4" (100") will raise the top of the railhead 2".   If your track is resting on quarter inch cork and three quarter plywood, for instance, that means you have to go up another inch for that, adding 50 more inches of run.  Add another quarter inch for the ties and rail, or 12 or 13 inches more of run.  Instead of getting there in 8', you'll need closer to 162", or nearly 14'.

Not to nitpick, but doing a lot of planning based on an 8' run would cause some heartburn when you try to get under that track...

[nkalanaga]

You wouldn't have to have the plywood under the upper track.  Cut it out and use a through-style bridge.  For a short span over one track the deck wouldn't be more than a quarter inch thick, and if one uses a minimum-clearance style bridge it can be less than an eighth of an inch.

Paul Mallory's bridge book includes a design for a bridge deck using crosswise 12 inch I-beams, closely spaced, with a steel plate over that, and the rails attached to the plate.  Put the floor between two plate girders and the entire deck is less than 3/32 inch.

CSX's approach to the Big Sandy River bridge in Catlettsburg, KY uses a similar floor, but has a ballasted deck on top of that.  They used the minimum-clearance floor over US 60, and regular bridge floors for other approach spans.