Easements and turnouts

[rcato]

Good Morning,

I am a beginning model railroader.  I have only room for a 5x9 or 5x10 table top.  I will be using 18" radius curves.  I want to have easements. 

- Can this be done using 22' radius sections or should I use Flex track?

- Can the 5x9 handle a 22" radius curve okay?

 

Thanks,

-Ron

[rcato]

Forgot.

If I use easements on an 18" radius curve (22") in conjunction with a turnout, what size turnout should I use.

 Thanks,

-RC

[bogp40]

Unless your plan specifically is calling for the 18", you should go for a larger radius. The layout width of 60" will allow a maximun radius of up to about 24" with easments. This is keeping the tangent (straight sections about 3-4" in from the edge of the benchwork).  Using flex track gives you the advantage of coming off the turnout and ease into the now larger radius. The easments should be longer than your longest piece of equipment. Even though this is not a huge layout, these larger turns and easments will allow you to run larger equipment, (Articulated steam, passenger  and longer rolling stock).

Smaller radius can be run on an inside track or sidings, small yards etc to the inside of the main.

The 5ft width may pose reach problems unless you can access the backside of the layout/ table. If the room permits, an "L" or "U" shape would work better. Generally a max of 3ft width is a comfortable reach. Ends can always "bulb" out to the 60" as you want for the larger radius. This is why you will see the "dogbone" look to many plans.

[wjstix]

To determine what will fit a given width layout in HO, subtract 4" (you need a couple of inches clearance between the edge of the layout and the track) and then divide in two. So for your 5' wide layout, 60" - 4" = 56", divide by two gives you 28" radius curves. You might want to go down a little to say 26"R to give yourself a little more room around the edges, but 28" would be the absolute max. (This is before factoring in easements.)

With sectional track, you can use a larger radius curve section to make sort of an informal easement. If you're using say Kato Unitrack, you can have a section of 31"R curve leading into a 26" radius curve for example. It helps but it's not really as effective as using "real" easements where you start at a very large radius curve and 'ease' into the tighter curve.

Since you describe yourself as a "beginner" you might find doing the easements and such a little hard for a first layout. I'd suggest looking at the Unitrack option...in fact, I'm using it on my new layout, and I've been in the hobby since 1971 !! It looks good and is easy to use - plus you can test out trackplans before making them permanent, giving you a chance to change or add things.

[IRONROOSTER]

 Yes, using 22" radius sections with 18" sections will give you an easement effect.   This will make a half circle wider than using all 18" radius although I am not sure by how much, but less than using all 22" sections.  Normally, an easement has a continuously decreasing radius using a cubic spiral, but is more complicated to lay and requires flex or hand laid track. An easement this way usually requires about 1/2" to 1" extra on each side depending on how you lay it out.

However, in your case with a 5' width, I would consider skipping the easements and go with the wider  22" radius - a half circle would be 44" across on the center lines and you have 60". 

If you use the Atlas #4 turnouts you'll be fine as these are really #4.5, otherwise use #5's.  Atlas snap switches are NOT #4, they are curved leg switches and the curve is 18" radius.

Enjoy

Paul

[markpierce]

The easement should start one car length before where the curve would have started without easements and continue another car's length further into the curve before coming to the fixed radius curve.  That is two cars' worth of easement at each curve end.

[wjstix]

One thing to consider is I think a lot of beginners in HO believe 18" and 22" radius is all that exists for railroad curves!! True if you Atlas snap-track you're limited to basically that, but you can use Bachmann EZ Track or Kato's Unitrack which have a variety of curves (in track with roadbed included, saving a step in construction).

In HO, generally 18"R is considered "sharp", 24"R is "conventional" and 30"R is "broad".

As I noted before, on a 5' wide layout you could use 26" R curves. Generally if you want to run full-size passenger cars with body mounted couplers (like Walthers  cars for example) the sharpest curve you can use is 24"R - although the larger the curve, the better the cars will look. I would try to avoid No.4 turnouts which are very sharp too. No. 6 turnouts will accomodate large passenger cars or engines with ease, and look good doing so. (No.5s are a good compromise if the line you choose offers them.)

p.s. with turnouts, the higher the number, the broader the angle of the switch.

Kato Unitrack

[WSOR 3801]

 Atlas does make 24" snap track, in code 83.  Might be worth looking into if running Walthers passenger cars, espcially 6-axle.  It is very easy to fudge flextrack into a curve that is just a little bit too tight. 

The Super Dome and Skytop that I have go through an Atlas #4 just fine.  The Skytop makes it around 18" radius, but looks awfully silly doing so.  The Super Dome needs 24"; it binds up and derails on 22".  If room is available, #6 switches work better. 

Here is my yard lead.  A #6 off the main, and tracks 1 & 2 have #6s, to lessen the S-curves.  After that I used #4s.  The lead runaround uses a #4, no S-curve. I can shove into these tracks way too fast and things stay on the rails.

[gerhard_k]

A true easement goes from infinite radius (a tangent, or straight line) progressively to the curve radius; its average radius is about twice the final curve radius. So, a 22" curve is much sharper than you want, if you are looking to use a single fixed-radius track section as an "easement" for an 18" curve - I would go for 36" or maybe 30". In any event, it's only a poor approximation.

If you're not using a Uni-Track type system, consider soldering (with rail joiners) an 18"-long piece of flextrack to the last piece of your fixed curve track, and then form an easement in this flextrack piece, using the bent-stick method or just your eye. The critical thing will be to allow the last few inches of the easement piece to achieve a very shallow radius, because it really needs to have a very gradual transition from the straight to minimize the "lurch" of entering the curve.

The additional radial distance will be 1/2" to 3/4" beyond where the simple 18" curve would end up. The larger impact upon your track plan will be that the curve is, in effect, 9" longer than the simple 18" curve, and on the typical space-challenged layout, this will eat up linear length that will force sidings etc. to become shorter - not what most small layouts can afford.

So - make your trade-offs and don't fret too much!

- Gerhard

IRONROOSTER

 Yes, using 22" radius sections with 18" sections will give you an easement effect.   This will make a half circle wider than using all 18" radius although I am not sure by how much, but less than using all 22" sections.  Normally, an easement has a continuously decreasing radius using a cubic spiral, but is more complicated to lay and requires flex or hand laid track. An easement this way usually requires about 1/2" to 1" extra on each side depending on how you lay it out.

Paul

[tomikawaTT]

Many years ago Ed Ravenscroft pioneered the use of fixed-radius 'pretend it's an easement' sections.  The ratio (curve radius = 1) for his 'easements' was 1.5 to 3 to straight, with each section as long as the longest car to be operated over it.  For an 18" curve, this would make the sections 27" and 54" radius - WAY larger than 22"!

Quick and dirty true spiral easements have to be laid with flex track.  Simplest:

• After locating your curve with sectional track, remove the section that would have connected directly to the first straight section of your non-eased tangent.  Measure the chord of that arc, on the centerline half way between rail ends at each end of the section.
• Measure the same distance along the tangent away from the curve.
• Offset the tangent outward approximately 1/25th that measured length.  (If you measure 9" the offset would be 3/8".)
• Where the tangent and the curve would have met, mark 1/2 the offset.  The centerline of your easement will pass through this point.
• Anchor flex track (fixed rail to outside of curve) along your tangent line, then curve inward until it mates with your curved sectional track. line.  Use a loose piece of curved sectional track to assure that there isn't a substandard-radius kink at the curved end of the easement.

Sectional curves make laying an exact radius easier.  Flex is less expensive for tangent track, and is the only way to form true spiral easements or to lay curves of other than standard radius.

Chuck (Modeling Central Japan in September, 1964 - with flex track and hand-laid specialwork)