Easements

N

Nomad

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Sep 26, 2006
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Elks Plain, Washington
Help please. I am using easements for the first time and don't know how to draw them for my track templates. If I have easements set at 24" radius and draw a 24" curve, does that mean there is no easement? And what if I have a 22" curve. How do I draw that out with a 24" easement?
I found a post after doing a search, but the info went right over my head. Did not make a bit of sense to me.
Loren
 
If no one posts to this before I get back to it, I'll try to answer one I get home to my references, so I can get it right.
 
Are you doing this on a computer, paper, or plywood?
What I do is offset the curve by half the gauge and ease from there, allowing a coach length or more each side of the end of the circular curve.
e.g.if you want a 24" circle, draw a 24.25" circle from the tangent and also a 24" circle with the same center and gradually work your way from the straight to the curve, starting about a foot before the end of the straight and ending a foot into the curve.
 
David, thanks for the reply. What I am trying to do, is make cardboard templates that I can lay on my table and then draw the curve that way. With 2' wide tables, I really can not use a yard stick as a compass.
Anyhow, my understanding of an easement would be to draw a 24" curve, a 22" curve outside the 24, and connect the two so you would start with a broader curve first, then ease into the smaller curve. Am I way off base with this idea?

Loren
 
Never mind.

I Googled easements and found:

trackplanning.com/easements.htm

Has an animated desc and a good text desc-at least I think so.

Have a look too, at the gizmo I use - 'A radius gauge' under Tips and Tricks.

All you are trying to do is to touch the circle with a straight line -the tangent point.
So lay out your radius and slide a straight edge carefully until it touches the circle.
 
An easement may also be known as a spiral curve - that is the radius is gradually, but constantly, tightening until it reaches the desired "nominal" radius.

One way to think of this (and to roughly approximate it) is to visualize some sectional track: straight, then a 22" radius curve, then some 18" radius sections, followed by another 22", then straight again. The songle section of 22" radius curve at each end acts as a crude easement.

Hope that helps.

Andrew
 
grewsome said:
With 2' wide tables, I really can not use a yard stick as a compass.
Loren
Click to expand...

You can still use a yardstick for laying out the radii on your layout: you simply need to use a second piece of wood ( 1"x2", or a strip of plywood, or even a second yard stick will work), screwed to the layout, near the edge, and extending out into the aisle. Pick a spot to be the pivot point on the outer end of this piece, and away you go. You may have to adjust the position of this extra piece in order to get the ends of the curve in the proper place, but this will allow you to experiment with varying radii.
I've seen the formulae for determining easements, and it made my head hurt just looking at them. You can simulate an easement if you use flextrack for your curves: lay out the radius between the endpoints of the straight track at either end of the curve, then using a piece of flextrack long enough to complete the curved section (solder several lengths of track together if necessary, doing so with the track straight) spike it down at the mid-point of the curve. Bend the free ends so that they overlap the straight track already installed leading up to the curve, making sure that the centreline of the as-yet-unspiked track does not bulge past (to the outside) of the centre-line you've drawn at your chosen radius. I did all of my curves using this method, judging "by eye" how much track to spike down at the middle of the curve, and where to fasten the free end to the already-installed straight track. If you make the connection right at the point where your drawn radius intersects with the straight, you'll have no easement. Instead, pick a point on the straight somewhere back from the drawn beginning of the curve - the further back, the gentler the easement. You can vary the degree of easement on either end of the curve, too, if the situation requires it. Once you've selected the point, cut off the excess from the ends of both the straight and curved track, install some rail joiners and make the connection, then spike down the balance of the curved track.

Wayne
 
Maybe someone could post a photo showing how to do easments the John Armstrong way. He explains it in the Track Planning for Realistic Operation book.:thumb:
I have seen this question several times and most pepole don't want to do the math to figure the cubic spiral. His way of doing the easements is very simple and easy. Maybe it is time to make a Academy show and tell on this.
Any takers?
 
Back in the early-mid 70s (I think) Model railroader had an article on easements. I think they used a cubic curve. Part of the project was a huge foldout with various easements drawn out on it for transfer to templates. The templates included radius marks so that they could be used to ease between two curves.
 
Notwithstanding I posted the address of a site that deals directly with the easement thing, AND provided details on a jig to employ, I must say:

Do your roads run more smoothly today than years ago, before formulae with two or three variables was introduced!

Even *For Real Roads* squeal and shudder in turns that have been shot, laid out and bent with the most sophisticated powerful machinery known.

The simplest and best solution to a problem that has grown up and is now eating it's young, is to use that horrible flex track for all curves.
Even if you soldered twenty lengths of flex together, you will have to deal with the same length of too long sliding track for any given radius.

It does not matter a whit whether the radius is 24 inch on a 4x8 or 30 feet on a 15,000 square foot club layout, curve must meet straight.

Template drawings are created with precise and accurate CAD, but at some point you gotta nail some track down and at some point your radii must transition to a straight line.
I don't care how many MRR articles have been penned or how much mumbo jumbo is cast about, you're gonna hafta eyeball it and test run, test run and test run.

When a comet is caught by the gravitational pull of a planet or star it is flung into space at a tangent and continues on a course that descibes a hyperbole. The gravitational pull of the star or planet affects the course of the comet which would, if there were no gravitational effect, move away in a straight line.

This easement thing replicates that phenomenon.

For every unit of forward movement of the comet, there is a formula to determine the radius of the arc, the radius' center point in space and the length of the arc the comet has travelled or will travel through. It's a mathematical deck of cards, a real ice breaker at cocktail parties, but that's how the spaced out guys plunk the shuttles down.

In most, if not all derailment and coach or car swing out problems on curves, the culprit is too much car or coach extending beyond the center point of the trucks. The reason logs on the truck in front of you swing into your lane is because the center line of the axles under the logs is 30 feet from the end of the logs, not because the road builders didn't know about easements.

Now we can close this thread and put the dead horse icon on it.
 
Chaprral,
Am I to understand that you don't belive in easements? The real railroads use them.
I too use them on my layout, they sure help. No more toy like jumping when the trains make the transition from straight to the fixed radius. IMO they are worth the effort to use.
 
Of course, the big difference is that instead of going from zero radius to 18" radius in zero
length, the easement provides a gradual transition from straight (infinite radius) into the
18" radius. The improvement in the appearance of an operating train, from what someone
recently called the "Lionel Effect", where a car jerks into the curve, to a smooth entry to the curve, is quite dramatic, in my opinion. (whatever that's worth!):D :D

Do your roads run more smoothly today than years ago, before formulae with two or three variables was introduced!
Click to expand...
Easements are best laid out with a thin bent stick. :thumb: No "variables" required!!:D
And even with sectional track, using a larger radius section to enter an leave the curve
provides a beneficial easement!
 
I call to the stand, doctorwayne.

doctorwaye, can you tell us what you do vis a vis 'easements'.

You can simulate an easement if you use flextrack for your curves: lay out the radius between the endpoints of the straight track at either end of the curve, then using a piece of flextrack long enough to complete the curved section (solder several lengths of track together if necessary, doing so with the track straight) spike it down at the mid-point of the curve. Bend the free ends so that they overlap the straight track already installed leading up to the curve, making sure that the centreline of the as-yet-unspiked track does not bulge past (to the outside) of the centre-line you've drawn at your chosen radius. I did all of my curves using this method, judging "by eye" how much track to spike down at the middle of the curve, and where to fasten the free end to the already-installed straight track. If you make the connection right at the point where your drawn radius intersects with the straight, you'll have no easement. Instead, pick a point on the straight somewhere back from the drawn beginning of the curve - the further back, the gentler the easement. You can vary the degree of easement on either end of the curve, too, if the situation requires it. Once you've selected the point, cut off the excess from the ends of both the straight and curved track, install some rail joiners and make the connection, then spike down the balance of the curved track.
Click to expand...

Until I invented the gizmo I did just that, using 2 inch dressmaking pins into the foam to hold the track along the center line.
When I put the gizmo on the layout lines, I wasn't impressed with the straight end of it laying parallel along the edge so I bent it into a very gentle curve and re-marked the center line of the track.

Relying on doctorwayne's evidence and realizing what I had unwittingly done, I now say yes, I do believe in easements.

Weasel clause: But I did it for asthetics adhering to a MRRing rule about avoiding track paralleling an edge.
 

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