Minimum Curve Radii in Staging Yard

[MGAcoal]

Thanks for all your insight -

I really was thinking that 28" was going to be the minimum, even in staging, especially with the longer rolling stock.  I recently just bought a piece of plywood, a perfect place for me to do some testing.  If all goes well, my U-shaping staging yard will be a run-though yard, almost in the shape of an elongated tear drop.  Trains will come off a helix from the upper level and proceed into the yard along about a 15' straight run.  The tracks will then begin to turn and proceed around a 180-degree curve almost in the form of a balloon, heading back in the direction they came.  They will traverse another 15' section of straight run (beside the other 15' section of straight run) ultimately meeting back up with the helix and returning to the upper, sceniked level of the layout.  If I have 8.5' to make the balloon and I start with 28" radius curves, I figure I can have 9 tracks running through the yard, maintaining 2.5" track center spacing.  I would like to have more, thus my original question about having smaller radius curves to allow more tracks on the inner part of the "U".  If I were to reserve the inner tracks of the staging yard to things like unit coal trains, could I get away with the tighter turns?

More thoughts welcome.

Mike

[loathar]

I agree with the 28" minimum. Especially if your going to be backing trains into a U shaped staging yard.

[trainnut1250]

Mike,

 

I'll add my voice to the chorus that says no smaller than 28".  89 foot cars overhang quite a bit on 28" radius. The combination of them on the inside and outside of the cuve will need some attention to make sure they don't cause problems.  Make sure you have enough clearance between tracks.  I know I sound like all the rest but I would test out the proposed radii with the cars and equipment in question.  On all tracks and all directions. 

I had to re-lay a section of staging track that I made too tight. Even though I checked it, I didn't check all the possibilities and one came back to bite me.  A cab forwad and a certain other loco wouldn't pass each other in a certain combination (whoda thunk??) Fortunately it was early enough to fix easily.

Be sure to keep the turnouts accessable and I would suggest kill switches for powering the individual sidings.  I used Atlas code !00 and Peco turnouts on all of my 300' of hidden track (one box of Atlas flex).  I was super careful and meticulous on this track and so far I am a happy camper.

Guy

 

[tstage]

Mike,

From what I've been able to find out, a simplistic answer would be no less than 6 times your longest car in inches for both looks and for proper coupling of cars.  (Some folks advocate a minimum of 8 times.)

For example, if your longest cars are 40' boxcars:

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40' X 12" = 480" divided by 87.1 (HO scale) = 5.51" X 6 = 33.1" minimum radius

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And that would be the inner most curved track of your Staging yard.

If we were to figure in your 89' auto-racks:

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89' X 12" = 1068" divided by 87.1 (HO scale) = 12.26" x 6 = 73.6" minimum radius

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Obviously, you would also want to have a minimum 2-1/2" center-to-center (CTC) track spacing on your curves for all radii out from that inner most track.

If we were to use the 40' boxcar for our example again, and Track 1 was the inner most curved track, here's what your concentric curved track outward would look like:

• Track 1 = 33.1" radius
• Track 2 = 35.6" radius
• Track 3 = 38.1" radius
• Track 4 = 40.6" radius
• Etc.

The CTC track spacing on your straight sections of your yard don't have to be as wide and can be reduced to 2" or 2-1/4".  Does that make sense?

Mike, in all reality, you might not be able to achieve those minimum radii for your Staging yard and you'll need to compromise a little (or a lot) because of room constraints.  Whatever you end up doing, be sure to test out your "swing" clearances on the curved portions of your Staging yard with your longest cars (i.e. your autoracks) BEFORE tacking your track down permanently.  You sure would hate to find that out after the fact.

Hope that helps... 

Tom

[selector]

As suggested, there are a great many variables. 

Let's say you have really good track laying skills and you do a bang-up job on your tightest inner curves.  Then you run 89' cars from Blue Horizon, Red flame, and Yellow Wagons and find that only the one(s) from Yellow Wagons seem to dislike the inner curves.  Is it something to do with speed, the track gauge narrowing, the quality of the trucks, the choice of couplers used, diaphragms on passenger cars, the wrong engine that forces couplers over too far....it gets very complicated.  Maybe all those offenders need is a little tuning, some deburring where the trucks swivel on their mounts.  Maybe they'll need some shaving of undercar equipment, or the steps are often a bit of a problem on tight curves.  The sill plate can cause problems.

So, it takes some thought, and some experimentation.

The best advice is to always err on the side of greater radii, all things being equal.  If you can remember to run shorter stuff on those inner curves, maybe you can get all the way down to 18", perhaps somewhat less.  The only way to know for sure is to do a mock-up and test things out.  Try the turnouts as planned and see if you run into S-curves that become the big headaches when all else works marvey.

A layout = the confluence of 1000 different, but not necessarily complementary, ideas.

[aav]

             If it were me i wouldn't go any smaller than that 28" in staging, especially on those 89 footers.  i think the minimum operating radius for those cars is smaller but i'd want as wide as i can in staging, becuase the last thing you want to be doing is constantly rerailing cars there,  especially if it's hidden or hard to get to.

[bogp40]

Hello All -

I have a quick question regarding curvature radius in staging yards.  What would be the absolute minimum curve radius I could get away with in my staging yard?  I am planning a "U" shaped staging yard and am trying to squeeze in as much in as practical.  I would like to have 2.5 inch track centers and I have the all the big rolling stock (i.e.  89' auto-racks, 85' flat cars, 86' Hi-Cubes, 6-axle diesels, and the like).  I might be able to have the smaller radius curves (inner tracks of "U" shape) spaced further apart (more than 2.5") if necessary.  I am planning on all visiable/sceniked curves having a minimum radius of 28 inches.  Any thoughts or advice would be greatly appreicated.

Mike   

It would all depend on how much space you have and how many tracks are placed. Is the 28" radius the outermost track? and all others inboard. Of coarse you know the inner tracks will have a decreasing radius. If the space dictates and even some of the inner tracks have to be down to a 20" or less radius, you can compensate for the type of equipment stored there. A hidden "U" shape is not really ideal and derailments can be frequent, I would install some rerailers on the straight sections. May help hobble a car on the ground to at least the rerailer.

[MGAcoal]

Hello All -

I have a quick question regarding curvature radius in staging yards.  What would be the absolute minimum curve radius I could get away with in my staging yard?  I am planning a "U" shaped staging yard and am trying to squeeze in as much in as practical.  I would like to have 2.5 inch track centers and I have the all the big rolling stock (i.e.  89' auto-racks, 85' flat cars, 86' Hi-Cubes, 6-axle diesels, and the like).  I might be able to have the smaller radius curves (inner tracks of "U" shape) spaced further apart (more than 2.5") if necessary.  I am planning on all visiable/sceniked curves having a minimum radius of 28 inches.  Any thoughts or advice would be greatly appreicated.

Mike