What is the minimum clearance i should have under a bridge so i can cross another track under it?
That depends on the equipment you are using…if you’re running double-stacked containers you probably want at least 24 scale feet clear over the rail.
So without double stuck container 2.5" should be enough?
2.5" might be too close. Find your tallest piece of rolling stock, place it on a piece of track and measure how tall it is. If it will clear the 2.5" mark, you’re home free as long as you don’t buy anything taller than that clearance.
Don Z.
3" may not be enough.
My big steamers will go into my cut-down HO tunnel portals that are now 2.9" above the rail tops at the apex with room to spare…about 1/2", to be exact. So, if you want factual advice, 3", plus or minus 1/4", is the bottom line to give you both looks and some security for future advancements…minus the double-stacks, of course. Sticklers for scale will advise that for true prototypical appearance, the minimum above rail tops is 3.5", or close to that.
I agree, 3.5 inches.
Athearn doublestacks take 3.75" . I have 4" clearance on my layout and no problems. I had to modify the Walthers doubletrack truss bridge because the douublestacks wouldn’t fit.
I may be pushing it (Especially if I get another engine any higher), but I have two bridges and they are 2 3/8 " high…close, but enough.
Quote-Athearn doublestacks take 3.75" . Wow! That’s tall. I just measured an Accurail tri level auto rack with a malibu van on top and it was a hair under 3".
NMRA standard is 3 inches above the railheads - but that was set before double stacks were introduced.
The best idea is to measure the highest piece of rolling stock you propose to run and add 1/4 inch. If you are stuck in the transition era, 3 inches should do - unless you have a model of Anzio Annie that you want to haul around.
Chuck (modeling Central Japan in September, 1964)
I’m using 3 1/2 inches, which leaves a little less than a 1/4 inch clearance.
USE the NMRA track gauge and…make sure your containers are completely seated in the well cars. The other posters are correct, NMRA standards are tight in this one area.
Tilden
In the real world bridges are suppose to be 18 feet high or so, so, that means the bridge should sit around 4 to 4 and a half inches above the rail. Also back in the days with many cantalever bridges they were all 18 to 19 feet high. So this means the railroad bridge would need to be about the sma height if not higher.
Happy railroading[(-D]
James
I use a 2x4 as a clearance guage.