Q:What is the min Radius for 1990's ERA

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gottaBreal

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Sep 13, 2006
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Im going to be running some Thrall 89' Tri-Level Enclosed Auto Carrier's and some Intermodal trains and wanna make sure I have large enuf turns so they look good rather than look like toy train.....im thinking 28" and 26" being the min for the Helix.

Thanks guys ill soon post my ideas for my 2 level layout.
 
I would suggest laying out a circle of track at 26 inches to see how those auto racks handle it. I don't think you can get away with less than 30 inches with 89 foot cars. You need to test at least 2 hooked together. They may go around the tighter radius singly, but then derail when hooked together.
 
gottaBreal said:
Im going to be running some Thrall 89' Tri-Level Enclosed Auto Carrier's and some Intermodal trains and wanna make sure I have large enuf turns so they look good rather than look like toy train.....im thinking 28" and 26" being the min for the Helix.

Thanks guys ill soon post my ideas for my 2 level layout.
Click to expand...


For long wheel base engines and cars I suggest 30"-36" and nothing less then 28"
 
Depends whether they have body-mounted or truck-mounted couplers. With truck-mounted, you can go as low as you said; with body-mounted, as others said.

However, for a helix, there's another concern. Since you'll have to build it to clear double-stacks, 26" and 28" sounds like it could result in a rather steep grade between levels. Often, a helix needs a larger radius than what your equipment actually requires. Of course, this depend on how long of trains you intend to run, and with what motive power.
 
Well I dont think I can fit 36" in my layout since I only have a rather small area. Also looking over the cost per 89' Tri-Level Enclosed Auto Carrier's and cost per 3 unit container train I could do those for alot less.

So if anyone has those Walthers 3 unit container sets let me know if 28" is ok for them to run.
 
28" should be fine. I have 26" - 30" radius, and run Athearn Auto-Maxxes with no problem.Though the spacing looks a little tight, and there is some unprotypical hangover, the still negotiate the turns. Like you though, I don't have the room for 40" radius.
 
The NMRA recommended minimum radii is here: http://www.nmra.com/standards/rp-11.html

The Layout Design Special Interest Group rule of thumb is a minimum radius of 3x the car length (measured over the coupler knuckle faces) for reliable tracking; 4x for improved appearance; and 5x for automatic coupling to work reliably. The rule of thumb assumes 2 of the longest cars coupled together with body-mounted couplers. The 3x rule for 89 ft cars would give about at least a 36" minimum radius for the helix, and ideally 48" out in the open.

You could probably get away with less as others suggested by using truck mounted couplers. In my experience, you can get generally get away with about 2.5X length for minimum radius, but the tolerances for misalignments in track, misgauging or wobbling of wheels, coupler mountings that are less than spot on, etc, all become much smaller. Also going below the 3x recommendations sets you up for string-lining with long trains (especially in a helix), and of course pretty poor appearance. Less than 2.5X can be done but requires undeframe and detail modifications, and truck mounted couplers. Long trains don't work.

Due to the growth in car lengths and train sizes modeling modern era in HO convincingly requires much bigger spaces than we are used to thinking of. If you do the math, modeling modern era in N takes just as much space as modeling transition era in HO.

my thoughts, your choices
 
ok i would like to run these 3 sets on the layout....will they handle those curves?
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Working the 3X formula in reverse, a 9" long car will operate successfully on a 27" radius curve. 9" in HO = 66 scale feet. So knowing the length of the prototype should give you the answer.

You really are the ragged edge for success trying to do a modern-era layout with 26-28" radius curves. Some suggestions:

1) change era to when cars were 70 ft or less

2) change layout plan to 36" minimum radius

3) switch to N scale - note 80ft cars in N need 18" radius curves according to 3X rule of thumb

4) modify rolling stock to or buy rolling stock with truck-mounted couplers. Build/use a test track and test every car and locomotive on your sharpest curve before putting into service on layout. Be prepared to shave underbody details that interfere with truck and coupler swing. Be prepared to weight cars and/or run short trains to prevent string-lining. Test the helix thoroughly before covering it up.

All the items, especially the testing, are essential parts of #4 when you are trying to approach the 2X length radius mark. Modern era rolling stock is about twice the length of transition or earlier era rolling stock - means you need a lot more space to achieve the same result.
 
gottaBreal said:
ok i would like to run these 3 sets on the layout....will they handle those curves?
09320000003944.gif
Click to expand...

I think that well car is designed for one double stack of a 40' container on the bottom with a 42',45', or 53' container on top. You are probably looking at 9" -10" in ho scale. If you choose to use double stacks & husky stacks, but forego the 89' autoracks, piggy back flats, or the latest 90' reefers, you can do fine with 26"-28" If you try to run the longer cars, you need to build some test tracks with "S" curves, to see how they work.
 
Alright....thanks alot guys for all your help. Im starting to think I will push back the ERA a few years so I dont have to worrie about buying a Warehouse to be the home of my layout.
 
gottaBreal said:
Alright....thanks alot guys for all your help. Im starting to think I will push back the ERA a few years so I dont have to worrie about buying a Warehouse to be the home of my layout.
Click to expand...
You need not push your era back..Just forgo the long wheel base cars and model general freight trains..I know the auto racks,pigs/stacks and auto part boxcars make a interesting and grade looking train but,so does the other modern cars.
 
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