I am going to change my 4x8 board design and add side shelves, so I need to create an overpass to exit the board. I think I will need about 4" over a length of about 8' and wonder the best way to create a slope on top of plywood? I have thought about using something like foam board but wonder how to SMOOTHLY create that gradual slope to hold the roadbed securely?
I am probably missing something really fundamental, but this is my first idea so would appreciate any advice/criticism of the plan. The 4x8 must stay as it is cantilevered in my garage so I can fit in my truck when I leave the country. The wife won't allow me to "play" any place else.
Cheers, Jake
Jake, that works out to 4%, and is considered very steep, even for a model railroad where space requires us to make compromises. If you want to be assured of better looks and an easier time for your engine, consider using 1.5" extruded foam for the surface of your layout...or at least that part of it. It will allow you to dip the nether rails by about 1" sort of like an overpass in some towns. The train runs at grade, or climbs a bit to the overpass, but cars are forced to descend a ramp and then climb out the other side on the pavement. You can do this with the foam, but with rails passing over rails. The net is that your climbs are all that much more manageable.
I would suggest Woodland scenics inclines. An easy way to achieve what you are after.
Magnus
I would suggest Woodland Scenics inclines and risers too. Easy way to add grades, plus if you raise all the track on risers and inch or so, you can also have the track that will be going under the other track drop down a little bit, perhaps allowing you to drop your grade to 2-3%. At 4% you're going to notice a significant drop in the amount of cars your engines can pull, perhaps only 50-60% of what they would pull on level ground.
http://www.woodlandscenics.com/ Look under "Foam System" and then "Inclines".
I'm partial to the plywood-cookie-cutter method for sub-roadbed. Smooth vertical curves are easy to achieve.
Mark
Woodland Scenics inclines. On a plywood or flat foam base, these really work. I used them for my roundhouse scene. It is 5x9 and I ran the incline all around the edge to get the track to go over itself.
Here is one pic that gives a hint. I covered the whole thing with plaster cloth and white paint.
Selector -thanks so much for answering me, sorry to be so long in getting back but I was traveling back from Guatemala and trying to think about my next step.
I also read about the Woodlands Scenic ramps and may look into that but what you say makes me think again. If I use the 1.5" extruded foam base over the plywood, then does one carve it out to create slopes like you suggested for the upper-pass/over-pass area?
I guess I am having trouble figuring out how to make fairly subtle changes in elevation and keep a sound, solid roadbed?
Maybe I am having too much time to think about this instead of trying something.
wjstix - thanks for the link. I like the idea and think you and Selector are correct that I do not want a 4% grade. A dip before and after the overpass bridge would sure help.
Jake, to answer your question about creating the nether ramps, two of them, you would use a wire brush to score the ramps and try to be even and gentle to the extent you can. You scrube away very little, in back and forth strokes, near the top of your ramp (don't forget to build in a curved vertical easement...you dont want an abrupt kink in your tracks at a lip...you want about 6-8" of a curve into your full grade, whatever that grade is. You scrub more away further "down" and then you must transition at the nadir where the crossing takes place, and begin to climb again.
The wire brush is a coarse way to get started, but you could finish with a small, long, sanding block and about 80-120 grit. Check freguently with a flashlight shining at the side of an inflexible straightedge, say a smallish level, placed on the area you are finishing. If you see a lot of light under the level, then you have a dip there.
You don't need perfection, just something reasonably close so that your trains aren't rollercoastering their way up and down the ramps. You can use plaster as an overcoat and screed it, like you would a cement pour, to get it to a true grade, or just use cheap acrylic latex caulking smoothed as a cover sub-roadbed. It will support your trains well once it sets.
Others may have better ideas, and hopefully they'll post.
ARTHILL -
The plaster cloth is a great idea. Can't believe I didn't think of it. Thanks.
- Harry
jake9 wrote:I am going to change my 4x8 board design and add side shelves, so I need to create an overpass to exit the board. I think I will need about 4" over a length of about 8' and wonder the best way to create a slope on top of plywood? I have thought about using something like foam board but wonder how to SMOOTHLY create that gradual slope to hold the roadbed securely?I am probably missing something really fundamental, but this is my first idea so would appreciate any advice/criticism of the plan. The 4x8 must stay as it is cantilevered in my garage so I can fit in my truck when I leave the country. The wife won't allow me to "play" any place else. Cheers, Jake
Jake, since you have a 4x8 your choices for a grade are rather limited. On my first Bear Creek and South Jackson I had twice around design with the town at a +5" elevation compared to the lower level. There were a pair of about 5% grades going between the levels.
While 5% sound horrible for a grade it's not as bad as some are saying because it's a short grade. Only 8' of cars (14+ loco) will be on it at one time. The rest of the train (if its a long train will be on flat lands (or on a grade going down).
4" in 8' is just about 4%. But remember, you can't just have a abrupt change at the top and the bottom from flat to sloped (or vice-versa). You'll need to make a gradual change between flat and sloped areas. This is especially necessary at the top of the grade. And even more so if this is on a curve so that your locomotives (especially and steamers) don't do an imitation of a whale breaching (leaping partly from the water) as they crest the top of the grade then fall back (hopefully) onto the tracks. Allow about 2' to transition between sloped and flat (and that's a bare minimum. If you have any long wheelbase steam engines they may not like it even with the 2' vertical easement (fancy name for the transition area between flat and sloped).
On my 4x8 the grades where just about no prolem at all. There were times when I ran trains around in a circle on the layout that were long enough so the engine on one part of the twice around was in front of the caboose on the other part. With careful trackwork (and you should be careful anyway even if there's no grade) you shouldn't have derailments.
Heres a link to my 4x8 layout web page. 4x8 layouts don't have to be flat...
This picture shows where the 5% grades - one down, one up - passed each other on my layout.
I'd say "go for it" (if you were looking at a 20' grade of 4% I'd say something different unless you were modeling a logging railroad).
Regards,
Charlie Comstock