Easement rule of thumb

The rule of thumb is the easement length should be twice the length of your longest car.  So, 23” for your 11.5” car.

Thank you Ken. I'll round it

Thank you Ken.

I'll round it off to 24 inches.

I will be needing another two easements later on both sides of a small bridge.

Easement

Deem,

Your question about length of easement spiked my curiosity so I checked my track planning book by John Armstrong and his recommendation was 25 inches long with an offset of 5/8ths of an inch.

Bill

Easement calcs, templates

John Armstrong’s book is excellent overall, but the easement table is pretty limited (after all, putting in enough tables to cover all radii and length would use a lot of pages).  You can do better in several ways these days with what’s online.

If you want to use the bent stick method, check out  https://www.eldoradosoft.com/easements.htm which has some recommendations and a formula to calculate a good offset for a given length and radius.  Using your 42” curve and 24” length, the offset should be 0.571”, or about 9/16”.

The other way is to use the postscript easement calculator liked to here:  https://model-railroad-hobbyist.com/subscribers-only/run-like-a-dream/trackwork#easements

Either way works fine, it’s not all that critical.

I'm having a hard time trying

I'm having a hard time trying to figure out how to mark/locate the tangent and offset plus where is the start and finish of the transition.

Hi Bill, I'm going to have to

Hi Bill,

I'm going to have to figure out how to mark the offset and the tangent on a scenicked surface.

Use the ballast (Luke...)

Dear Deem,

From the pic, it looks as if the ballast line (and the yellowish ??? between the ballast and the green grass),
along the straight portion of the turnout at right,
forms a pretty parallel-to-centreline offset line, which could be used as a reference?

AFAIK, basic tangents only need an inch or 2 offset from the centreline in order to create a practucaly easement?
(I'm sure Joe F's "Run Like A Dream : Trackwork" book will have something to say about this?)

Happy Modelling,
Aim to Improve,
Prof Klyzlr

Make a template?

Maybe making a template would help?  Draw out the easement full size on a piece of cardboard, cut it so the track centerline is one edge.  You can temporarily tape pieces of cardboard/paper to a large flat surface like the floor and use a piece of scrapwood, or maybe a broom handle or anything that’s more than 42” long as a compass to draw the curve, extend the offset , and draw the tanget, then use the bent stick method to lay out the actual easement.

Prof Klyzir, Is the length

Prof Klyzir,

Is the length between these two lines the transition? It is about 25 inches. The white gauge is a 42" radius.

Ken, So the long black line I

Ken,

So the long black line I have put in is the tangent? 

The short line with the arrow pointed at it, the offset? 

I'm still trying to figure out where the drawn 42" radius will go? Right up against the short line?

Laying out the easement

That turnout is straight (not a Y) right?  The easement doesn’t start until the track is no longer straight.

The point of tangent would be where you start curving the track, at the frog end of that turnout.  Get a yard stick and lay it out along the straight track, and set it so the end of the ruler is half the easement length past the tangent point (12” in your case).  Mark that point.  Use a square to get a right angle from the track centerline at that point.  The center of the curve is somewhere out along that line.  You can find exactly where by measuring out the radius plus the offset (42 9/16” in your case). You can use that center to draw out where the curve is, and continue it to at least halfway through the easement.  So, now you have the point the easement starts at (the point of tangent), and the curve, and you have the point halfway through the easement that’s in line with the tangent which is the offset (9/16”) away from the curve.  Halfway between that point and the curve (9/32”) is the track centerline at the center of the easement.  Measure the other half of the easement length along the curve and that’s the other end of the easement.  Use a piece of rail or something to line up on the tangent, the halfway point, and the curve, and there’s your easement.

I appoligize for the wordy description, it’s actually pretty easy to do.

Black lines

Yup that long black line is the tangent.  The arrow you drew points at the end of the easement.  Measure half the length of the easement further straight along that black line (past the actual track), and that’s the middle of the easement, the point at which you measure the offset to the curve.  And the point from which you can take a right angle and be in line with the center of the 42” radius curve.

I’ll draw a bit of a visual aid tomorrow morning if the above verbiage isn’t clear.

Prof Klyzir, That yellowish

Prof Klyzir,

That yellowish is cut down grass. That will be filled with cork roadbed.

I tore up the track because I want to widen the radius for my passenger cars and self propelled ones, but kept the homasote underneath.

Ken, The turnout is

Ken, 

The turnout is straight. 

Very informative and I'll have some more questions for you, but I'm calling it a night and will get back to you.

I've updated my line by what you have told me.

Thanks.

That is very kind of you to

That is very kind of you to draw a visual aid for me. I look forward seeing it.

  "I tore up the track

Hi Dee,   I'm curious, how do you plan top significantly change the curve radius if you leave the homasote where it is? As for the easement , don't sweat it. Your 42 inch radius is a wide curve for HO scale so the cars will look fine going into it as is. Just draw a right angle line from the end of the straight track and measure 42  1/2 over and draw your 42 inch radius curve from there, relax the curve for the first 24 inches to blend from the tangent to the 42 inch curve. Flex track will form a natural easement by it's self if you let it relax at the end of the curve. Since the radius point will fall in the aisle in your case you will have to put something temporary there to measure from. A heavy piece of furniture might work if you can clamp a board to it in the right spot, or perhaps clamp a board onto the benchwork extending it out a bit beyond 42 inches.  An even  easier way to create the easement is to just draw a template of a larger radius curve say 60 or 70 inches and use that for the first 24 inches of the curve ,switching to the 42 inch radius at that point. ....DaveB

Diagrams

An overview diagram.  The little angled line represents the turnout you have just before the curve.

Zoomed in on the easement part.  The short red line is the offset.  You extend the tangent half the easement length past the start of the curve (12" in your case), then at a right angle to that measure out the offset (9/16" in your case), and then another 42" to the center of the circular curve.  Use a pencil and string (or a trammel, or a large compass) to draw in the circular curve.  Measure 12" from the offset line along the circular curve to find the other end of the easement.  The green line is the bend stick method easement.

This NMRA datasheet has a nice illustration of doing the bent stick method for drawing out the easement once you have the various points located:  https://www.nmra.org/sites/default/files/d3b3.pdf

Hope that helps.

DaveB, I am going to trim off

DaveB,

I am going to trim off a little bit of the homasote on the inside and add a bit on the outer part. I ran out of homasote and liked the nice job I did on laying it and decided to keep that section of it.  

I'm just figuring out how the flex track forms a natural easement. I just did it with estimating the points. I regret giving my tripod away, as I could have used it for making the radius.

On the right is an easement to a short 36" radius I did by eye ages ago. And on the left a n easement to a 42" radius. 

  "I am going to trim off a

Hi Dee, Yeah that's what i'd do if most of the homasote is still in good condition. If you are only moving the track over a little bit the rails might still end up over the original homasote with just the end of ties hanging over. In that case just some foam carved to ballast angle can be slipped under the end of ties as there is no load on them. You track work looks nice and flowing with those broad curves....DaveB

Very helpful Ken and

Very helpful Ken and especially in regards to understanding the method.

I will set up a board or something I can put a stick on to make the radius. I  drilled a pivot hole in the stick and 42 inches from it another hole to put a pencil in it. I just need to get something take a tremble point.

Thank you so much for the drawings; they are a keeper.

Thanks DaveB,I will soon

Thanks DaveB,

I will soon have to get out my passenger cars; that will be the real test to see how nice the easements are to the broad curves.

I extended the transition

I extended the transition more to make the passenger cars look better on the curve.

To do this I needed to have the 42 radius curve near the back edge of the layout, which I can live with.

I needed to have the 42 radius curve near the back

Hi Dee,  How will this affect the placement of the bridge as you go farther around? Keep in mind that the curves will look less sharp when viewed from the layout level. From overhead they appear sharper than they do from where you will normally be viewing them.  42 inches would be considered a broad curve for HO scale. My S scale layout has 46 inch curves on the mainline and 27 inch in a couple of industrial areas( the prototype was originally a trolley line when built)....DaveB

I think I will be OK

I think I will be OK DaveB,

I am entertaining the idea of cheating a bit by putting in a very large radius throughout the bridge instead of having long easements on each side of a straight track on the bridge. As you said, curves will look less sharp from ground level and I'm hoping this is the case for the bridge.

I am only pining down the flex track temporarily to experiment. Hopefully get some temp power to it for a session before laying roadbed down.

I'm please with the easement and you can see how much wider the new easement and radius is by looking at the homasote roadbed exposed on the left of the track.