Turnout Number that equates to a 22"R track curvature?

[rbryce1]

I would like to insert a Bachmann turnout into a bend that needs to be a 22" radius curve.  I know a #5 turnout matches up well with an 18" Radius.  Does anyone know what turnout number equates to a 22" radius?

[rbryce1]

Well, I find that a #5 equates to an 18" curve as I thought and a #6 equates to a 33.1/2" curve.  Looks like a 22" curve just missed the boat on this one.  Don't suppose anyone has seen a Bachmann # 5.3 turnout??   

Didn't think so.   

[J3a-614]

Unless you have a space problem, or perhaps a geometry problem (sectional track may only fit certain ways--an advantage to flex track and hand-laid track is that it isn't tied to specific fits), I would go ahead and use the No. 6 turnout.  It will give you an "easement effect," starting the curve gradually, then sharpening a little more before going into the curve.

Real railroads found out long ago that "eased" or "transitioned" curves really improved operations.  Their surveyors and civil engineers use curves from tables to lay out their easements, which usually follow the mathematical formula for a cubic parabola.  For us, that's a lot of fuss and bother, and the real easements used can be incredibly long; some easements would look almost like tangent (straight) track in the space we have for our models.  The reason for this is that train speed and the time it takes to transition at that speed from the tangent to the curve or back are important; particularly for passenger trains, you don't want to go directly from straight to curve, it will make for quite a jerk.  Some roller coasters, particularly older wooden ones, don't have eased curves, and you feel a shock going into a turn (of course, that's part of the thrill of a roller coaster). 

Fortunately, we don't have to worry too much about live passengers in our trains (unless you're concerned about a spider riding as a hobo or something).  For us, a turnout leading into a curve, or a section of track about double the radius of the curve and about as long as the longest piece of equipment that will run through it will work and look fine.  Those who work in flex or hand-laid track have used things like bendable sticks to lay out such curves; the results using that technique look and work great, because you don't have a fixed radius for any length in your easement or transition, which is how a parabolic easement comes out.

Surprisingly, it is possible to run longer cars around a smaller curve with an easement than to run around some larger curves without one.  The reason for this is that coupler swing and the angular mismatch between cars is greatest when one car is in the curve and the other is still on straight track.  In an easement, the greatest angle approaches more gradually, and is not as severe for a given radius, as the cars are following through a gradually increasing curve, instead of going into a curve all at once.

Anyway, if it fits, use the No. 6.  If you get to do so, even as a temporary mock-up, observed how smooth a train runs between the straight track and the curve, compared with going directly into a curve.  Believe me, it's easy to see, and it makes the train just flow into your curve.

[J3a-614]

At the risk of sounding too technical, here are some links to discussions on eased or transitioned curves:

http://www.modelrailroadforums.com/forum/showthread.php?t=3396

http://modeltrains.about.com/od/layoutconstruction/ss/easements.htm

http://modeltrains.about.com/od/layoutconstruction/tp/curve_easements.htm

http://modeltrains.about.com/od/layoutconstruction/tp/track_curves.htm

http://cs.trains.com/TRCCS/forums/p/74981/902263.aspx

http://www.trackplanning.com/easements.htm

Hope this helps out.

[jward]

a 1/2  section of 22"r should be pretty close to a #5. this is assuming you want to use said curve section to bring a track parallel  to the straight route through the switch. if you are looking for a drop in replacement, there is none.

[rbryce1]

Yes it is a drop in replacement, and I'm afraid you are correct, there doesn't seem to be one.  I will have to re-think the feature.

[MilwaukeeRoadfan261]

I had the same issue and have found that an atlas snap switch does the trick.

[rbryce1]

My problem is, the layout is 98% complete and I used all Bachmann Nickel Silver track with pre-formed roadbed, and I pretty much need to stay with that.  I know I can probably use cork roadbed under the turnout and try and adapt it to look like the Bachmann roadbed, but then I have a Nickel Silver and brass track combination, which I don't want. 

Hey Bachmann --- I've got a great idea for a new product!!  Right and Left Turnouts using a 22" track radius.   

[jward]

atlas no longer makes brass track. their 22"r switches are nickle silver, but i don't think they're available in code 100 so you'd have a rail height issue with ez track. they also have a 30 degree curve which doesn't match up well with bachmann's 22 1/2 degree full and 11 1/4 degree half curves. 

have you tried using anyrail? it's a cad type layout design program which has an ez track library. you can design your layout on the computer and tweak it until everything fits. since the demo version only allows a limited amount of track pieces to be used, you can redesign just the affected area.

[Jhanecker2]

Life-Like makes a 22" radius turnout  in Nickel silver if you add their transition adapter track before  & after, you might get close to what you need .  Checkout Walters's reference catalog under "tracks" J2.

[Doneldon]

rb-

Many (most?) model railroaders paint the sides of their rails a rusty brown to look like life. If you did that,
the narrow ribbon of mismatched metal would become almost unnoticeable.
                                                                                                              -- D

[rbryce1]

Thank you and all are great ideas, but my track layout is 95% complete including sidings, inclines and bridges and the locations for a lake and river.  Far too late to re-arrange things.

The siding I wanted to insert was actually an afterthought and is not really required in the overall plan.  It would have just looked cool with an old steam engine I purchased and a construction crane car I have.

I'm afraid that all the methods for getting the turnout in the existing curve will have more negative consquences than not having the turnout at all.

I'm sure something will come to me for using this new setup.

Again, thanks, lots of good ideas, just too late to incorporate them.

[Joe Satnik]

Dear rbryce1,

The closest you are going to get is the Atlas Code 83 turnouts:

544    22" Radius Snap Switch Left Hand - Manual
545    22" Radius Snap Switch Right Hand - Manual
546    22" Radius Snap Switch Left Hand - Remote
547    22" Radius Snap Switch Right Hand - Remote

Straight length = 10.5" (vs. 9" for 18"R Snap Switch and Bachmann Remote)
Offset length = 2.05" (vs. 1.51" for 18"R Snap Switch and Bachmann Remote)
Radius = 22" (vs. 18" for 18"R Snap Switch and Bachmann Remote)
Degrees of turn = 22.5 degrees (vs. 20 degrees for 18"R Snap Switch and 30 degrees for Bachmann Remote)

The straight length difference will add 1.5" to your layout.  This can be compensated for by reducing a regular straight along that side from 9" down to 7.5", either by cutting, or by using 4.5" and 3" straights.

The most important feature is that the turnout's geometry has a true 22"R curve with 22.5 degrees of turn, which precisely matches a Bachmann EZ-track regular 22" curve.

If you don't understand what the "offset length" is, you can see it by laying a regular 18"R-30 degree curve on top of a Bachmann Remote turnout.  You will see the offset length at the points end of the turnout.

Obviously, you will need to buy transition joiners (Atlas #551) and cork roadbed to match up with the Code 100 EZ-Track.

Hope this helps.

Sincerely,

Joe Satnik

Edit-orial comment: My thoughts are that Atlas should have made a 22" Radius Snap Switch in Code 100 within a few years after the intro of the (18"R) Snap Switch, which may have been in the mid 1950s.   

[jward]

joe,

the true track 22r has a 30 degree turn. it is also the only one illustrated on the atlas web site. the non roadbed 22r switch is obviously different than the true track one in terms of geometry.

[Joe Satnik]

Dear jward,

Thanks for the heads up.

Wow, Atlas sure isn't standing still.  They've done both versions of the 22"R turnouts since 2009, my most recent catalog.   

I wasn't sure how they were going to solve the "wide track bed forces a longer divergent route" problem, as there is no pretty solution for it. 

According to the Anyrail.com track CAD program,

Atlas HO Tru-Track (Code 83 with roadbed) 22"R turnout numbers 482 thru 485:

Straight length = 10.5"
Offset length = 2.05"
Radius = 22"
Degrees of turn = 30

The geometry problem is how to get from 30 degrees of turn back to a multiple of 22.5 degrees. 

Turns out Atlas offers 1/3 22"R curves in Tru-Track, which has 7.5 degrees of turn. 

Two 1/3 curves = 15 degrees of turn, which can be added to 30 to make 45, which is a multiple of 22.5 degrees. 

Another problem with 30 degrees of divergent route is making a reasonably close parallel siding.   5.89" on center distance is about 40 scale feet, which is triple normal yard spacing. 

A 22.5 degree divergent route (non-roadbed Atlas 22"R turnout) yields 3.36" on center distance, which is under 23 scale feet. 

Hope this helps.

Sincerely,

Joe Satnik