What is a reasonable and realistic grade for HO scale fly overs? I want to model a fly over a yard, or something simular and I have not been able to find slope or grade for this sort of thing. I believe 3 1/2 inches of clearance is needed to pass over autoracks and double stacks.
For very short distances you MIGHT get away with 4% or even a little more, depending on your motive power. But you may be severely curtailing your train length, however…
For most modern locos, 2% is a good safe number for a reasonable length train. 4% or more will normally result in severe traction problems not to mention a really phoney look. In real life, roads attempted to keep grades below 1%, but few of us ever have that much space for inclines. In plain english you will need a ramp 12 feet long on each side of your flyover and longer would be better. If you are willing to run shorter trains, 8ft will work, but not well. J.R.
I used the Woodland Scenics 4% incine sets. They are steeper than most people want but the only thing I could fit on my small layout (9’x8’) I got the track laid this weekend and have been running my train to test it all out. I do have a couple problem areas to work out…but not the inclines.
I would keep it about 1.5% to no more than 2% grade…a 1.5 grade will be approx. a 1/4" rise every 16"…the 31/2" is standard height but if you want to run a consist of double stacked container trains then i wouldn’t go under 4"…had to tear down an overpass once that was built at 3 1/2" then rebuild it to 4" because the container trains wouldn’t go under it at 31/2"…chuck
A fly-over usually has a short, steep grade. Sustained grades should be as shallow as possible, but since an entire train isn’t on a fly-over grade at once (at least on the rpototype), a much steeper grade can be used.
I have a 2.7% grade on the ‘hill’ - There is 270 degrees of 22" radius at the end of the climb. This limits my P2K GP9’s to about 11-12 cars weighted to the NMRA standards. My BLI USRA Heavy 2-8-2’s can handle about the same load. My Spectrum 2-8-0’s can handle about 9 cars at most on that grade. I also have a Spectrum 4-6-0 and it will handle about 7-8 cars on the grade. Then there is my Atlas RS1 - that thing is heavy and will pull 20+ cars up the hill!
Jim Bernier
Would my engines be okay with a 2% grade of about 48 feet in length to climb about 12" in height with 24" Radius Curves? I have mostly P2K, Athearn, Atlas and Kato diesel engines, and as far as steam, I have an old ( About 12 years old) Rivarossi Challenger, a couple of Bachmann Heavy Mountains, and a couple to 3 IHC Premiere’s and a Reading 4-8-4 from Precision Craft. I am only planning on 15 car trains (Maybe an occasional 20 max, but probably not too often, cause I don’t think I can get a 20 car train to fit in staging). Will this do or should I shorten the train lengths; also I am planning on 4 engine lashups, except for the steam. I might be able to go less with the overall grade, but not too much that I can figure, and I don’t really have room for 24" Radius as it is, so to go wider is probably out of the question. But I don’t wanna destroy any of my locomotives either.
– Thanks
----> Mark
Another way to reduce the grade is to have the lower track on a grade also. The lower track will go down while the upper track goes up until you reach the overpass. This will effectively cut the grade % in half.
Doug