Shown (in the link below) is a hi-cube box on my code 55 track... the beams will support the upper level in my layout... is this enough clearance (as I dont think I'll have very many cars that'll be higher than this one)? http://www.geocities.com/nscale_lover/space.html
I'd consider whatever the tallest loaded car might be, that you'd ever possibly use. For my purposes, I always used a loaded tri-level auto-rack. Don't know how another more modern car might compare. Such as a double stack well car. It's good to see you're looking carefully at this, now. Instead of finding out by accident later.....! Boxcab E50
Mike, If you think you EVER will run doublestacks, it'll have to be higher. Very wise to consider this now, rather than wait until later when you can do nothing. In my experience, the Con-Cor doublestack (converted to MT trucks and couplers) with two Con-Cor containers is the tallest thing on the railroad. Don't forget Atlas is coming out with the articulated autoracks later this year; I understand these may even be taller, but until I have them I can't say for sure.
I think the LBF Sky box cars are the tallest cars out there right now.If you have one of them it will make a good clearance checker.
I use a double stack car to check clearances, plus a little lee-way. Not sure how much clearance above the car is neccessary on the prototype. On my previous model railroad, I had one place which was VERY tight for a double stack car! Don't think it would have been allowed in real life
i added a strip of balsa at the bottom of each pier just to be on the safe side... I think it was 1/32". There's a nice clearance space now, even over my above my triple deck auto carrier
Check with your local Hobby Shop and see if they have an NMRA N-Scale Track Guage. This is an item that every layout builder should have. It will tell you if you have enough overhead clearance, if your track gauge is ok, and if your switch points are in gauge. if the hobby shop doesn't have one for sale, aska round for a local member of the NMRA, they can order one thru the NMRA Headquarters.
I'd be safe and make the clearance 51mm/2" if you can. A loaded double-stack with 9'6" containers is around 21' scale or 42mm/1-2/3" high. As mentioned above the skyboxes are higher again, probably closer to 22' scale. These measurements are from the top of the rail, BTW.
