I am 5’-1" tall and want to build a 4x8 (Ho scale) multi level train benchwork with a double track helix at one end of the layout for going between levels. The lower level will be a industrial yard with a turn table and maybe a locomotive round house. I will also have my neices and nephews over to watch it run and maybe operate. I am wondering what heights i should put each level at? Any suggestions would be helpful. Thanks, Roy Brownson Jr
[#welcome]
4’ x 8’ith a helix? Is the helix part of the 8’ table or is it next to the table.
Here is Helix of LION on the end of an 18’ x 5’ table (two pingpong size tables pushed end to end).
As ewe can sea, it takes up a lot of realestate. It only lifts the train about 5 inches from the west side of the table to the east side of the table, but of course a helix takes up no more square feet no matter how high it goes.
Look at the resource page on my website to see my track plans. I have three decks along the walls, but the helix and/or nolix are on the tables.
ROAR
Seeing as you are 5’ tall, I’d make the top level 48" and the bottom level 30 or 36" tall. I assume your helix will be free standing, otherwise you will have no room to build a railroad.
The size of your table sort of dictates what era or kind of layout you will build. No long distance passenger trains for you, no unit trains either.
On a 48" wide table, your outside radius will be 22" and your inside radius 18". No big locomotives or 85’ cars for you.l
ROAR.
The maximum radius you can fit in a 4-foot-wide table is 22". In HO scale, a helix needs a minimum of 4" of vertical clearance between turns (3-1/4" for the train, 1/2" for plywood base, 1/4" for roadbed and rail). The linear length of one turn of helix 22" radius is 3.14 x 22" x 2 = 138". 4" of rise in 138" of distance = 2.9% grade. That’s very steep, but doable for short trains pulled by engines with good traction. An inner track of 20" would have a grade of 3.2%. I’d use that track only for descending to the lower level.
Respectfully submitted, the issues with a helix that tight are more than just the nominal grade. There is an additional effective grade caused by the friction of the curves. The empirical estimate (dating back to John Allen) is 32/R in HO, where R is the radius. 32/22 = 1.45%, which would be added to the 2.9% nominal grade for an effective grade of nearly 4½%.
At radii that tight, 2" is not enough separation between curved tracks. NMRA S-8 would recommend at least 2½" (and even that might be a little tight). That would make the inner helix track 19½" radius or less.
More importantly, trains on a helix that tight have a tendency to “stringline”, or derail across the center of the curve, due to the build-up of oblique forces through the couplers.
Finally, the helix itself would take up half of the 4X8 surface area of the lower deck. A helix is not really a net positive for the Original Poster’s situation.
Edit: not to mention the framework needed to support the upper 4X8 sheet
My HO layout has a single track 30” radius helix that has a total rise of 10¼” at 3.55%. My locomotives that have added weight do not have any problems pulling 20 cars. Locomotives without added weigh do have problems pulling more than a dozen cars.
The helix takes up roughly a third of my 14’ x 10 layout. I used ¼” plywood for my helix supported from the sides with notched 1” x 2” pine to keep the track clearance as low as possible. Even though it was over 30 years a go when I did the design drawings and construction I still remember the surprise of how much room the helix took, it didn’t look that big on paper. I’m very happy with the way it turned out and would do it over again if I was starting over.
