Flying Junction / Flyover grade

[rrinker]

I want to include a junction between two double-track mainlines using a flyover. Has anyone incorporated one of these int heir layout? What sort of a grade did you use to get the required vertical seperation? My authority in these matters, John Armstrong's Track Plannign for Realistic Operation mentions using "steeper than average" grades in the "3 to 5 percent range". Just wondering what anyone else has done here, and how well it works.

--Randy

[canazar]

Randy,

Well, here is a rule of thumb for grades.. for a 3% grade you would need 100inches to come up 3". I have a bridge of a upper line that runs above my other main lines. I "just " got away with 3 inches of height. I still had to go back and shim it another 1/8 inch when i ran my double stack intermodal cars. First time around I stuck a container right into the bridge. DOH! Only good news I doubt I am the first to do it. <GRIN>

We have some modules in out HO club that have some stupid high grades on them. But they work due to the fact the trains are short, and the grades are short less than a couple of feet. 100" is over 8 feet. That a lot of grade for an engine to work.

Good luck woth it. it may be alot of work, if you have the room, it would be cool. I love it when I have 2 or 3 trains running under the bridge with one coming over the top one. Great railfanning site!

Best Regards
John Kanicsar

[Anonymous]

Another aspect that makes a flyover more convient is if you have the lower track drop and the higher track rise. This way you can get the 3-4 inch seperation in half the distance. So for a three percant grade each track would need 4 feet from the flyover to get to the desired height. With a 4 percent grade your looking at 3 feet from the flyover. This way you have a steeper grade but it is for a shorter distance then if you went one track level and the other raised. Hope this helps
Andrew
Edit-I was assuming HO scale for these calculations