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Verticle Easements

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  • Member since
    February 2005
  • From: Vancouver Island, BC
  • 23,330 posts
Posted by selector on Wednesday, March 20, 2013 11:03 AM

Besides the solid understanding that an easement is needed on both ends of the contiguous grade, you must also keep your eye on the ball.   Or, in this case, the clearance/height that you desire to attain when you reach the acme of your rise.  Nice long vertical transition curves will look and perform great, particularly for the sake of couplers staying hitched and for the locomotive's traction, but what happens in between them?  You still have to get that planned height differential at the top, and the 'easements' eat into that work that the contiguous/consistent grade is meant to achieve for you.

Do you have the length left between easements to get the height you need?

Crandell

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  • From: Central Vermont
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Posted by cowman on Wednesday, March 20, 2013 8:26 AM

Thank you all for your input.  I think I would have had it about right, but some of the information clarifies and solidifies my ideas, so I should be very close when I first lay the grade.

At this time I am not trying to achieve an up and over, so I can be generous with my easements, top and bottom.  If I do decide to so an overpass, I'll make sure to have a sufficient easement. 

I am not using cookie cutter and I know that equipment can make a big difference.  I am doing transition era, with a loco fleet from 2-6-0 to 4-8-2 and four axle diesels.  When I put the grade in  place I will be sure to test the easement throughly with all the locos, before putting the final touches on securing it in place.

Thank you again,

Richard

  • Member since
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  • From: huizen, 15 miles from Amsterdam
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Posted by Paulus Jas on Wednesday, March 20, 2013 3:02 AM

tomikawaTT

 Let me make it a bit more general:

The vertical easement needs to be four times as long as your longest rigid piece of rolling stock.

IMHO this is not correct. The length of a vertical easement depends, besides the length of your longest piece of equipment, also on the steepness of the grade. The length of an easement should be one carlength for every percent of change of grade. With a 4% grade the length is four carlength. with a 5% grade five carlength etc.  By drawing the grade as a tangent the required extra length is about half the length of the easement.

In my drawing I made a red-coloured remark: the percentage of the grade and the length of the easement (in carlength's) should be the same.

BTW the above figures are conservative.

The construction method of Tomikawa is full prove. It is maybe old school, when it comes to building inclines with vertical easements the L-girder with cookie-cutter style plywood method is hard to beat. Adding or replacing a joist or re-adjust a riser is all you have to do.

Smile
Paul

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  • From: Southwest US
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Posted by tomikawaTT on Tuesday, March 19, 2013 4:31 PM

Paulus Jas gave a very good example of one specific vertical easement.  Let me make it a bit more general:

The vertical easement needs to be four times as long as your longest rigid piece of rolling stock.  This could vary from a few centimeters (!% grade operated over by teakettle 0-6-0Ts and ore jimmies or JNR 4-wheel freight stock) to preposterous (do you really want that loaded Schnabel car to climb a 5% grade???)

As a general rule, to handle all HO rolling stock, allow 13 inches (330mm) car length.  That still won't help the Schnabel car, I'm afraid.

If your layout has cookie-cut plywood subgrade, that will form a natural easement if secured at the points where the easement ends - and beyond, in both directions.  If the level surface and the grade formers are foam, you can make a pair of templates by making a drawing similar to the above on cardstock, bending a batten to the exact curvature.  If the curve is then cut out, the convex template will give the level to upgrade easement, while the convex side will help form the upgrade to upper level easement.  Creating the actual easements will require filling the space at the lower end with something readily formable (ground goop, drywall mud...) and attacking the upper end of the grade with a sure-form tool or something similar.  Have the Shop-Vac handy.

Chuck (Modeling Central Japan in September, 1964 - with lots of grades and lots of vertical easements)

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  • From: South Carolina
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Posted by Train Modeler on Tuesday, March 19, 2013 4:00 PM

Stating the obvious here, but you need it for the top and bottom.

I kind of like the formulas above and if you have 3 car lengths and they're long cars, then the easement will be longer.   

I also like the wooden yardstick method.  Where I clamp the yardstick down on one end and bring it up(or down) on the other end.  I have done this with some Atlas flex track on the yardstick and pulled some cars(or whatever pieces of equipment that will be the worst) over the transition section to test it.   Then I mark the height for every 3" or 4" of horizontal to get my rise over run.  It is not consistent when trying to maximize. 

It's somewhat an exponential curve at both ends.

Richard

  • Member since
    October 2007
  • From: Dearborn Heights, Michigan
  • 364 posts
Posted by delray1967 on Tuesday, March 19, 2013 1:16 PM

I've never seen a solid formula that works for everyone; the one above looks like a good start though.  What works for you will depend on car length and car type.  If the trucks are close to the end of the car, the coupler vertical movement will be less than if the trucks are set further in (long lever vs. short lever).  Like wise, longer cars will behave differently than short cars (89' flat cars or passenger cars vs. 35' hopper cars) because different amounts of the car will be on the level than on the grade.

You might want to use the above formula but add a few car lengths, if possible, to account for drooping couplers, or other such variables.  

http://delray1967.shutterfly.com/pictures/5

SEMI Free-Mo@groups.io

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Posted by Doc in CT on Tuesday, March 19, 2013 9:15 AM

1/8in in 12in is about a 1% grade (96/8 = 12).  One approach might be to to provide a vertical easement of 1/2 the final grade for the first foot or so (depends on the wheelbase and overhang of your equipment e.g. the "cow catcher").  Clearly the greater the final slope the longer the easement section would need to be.

So in your case the first foot of track should rise 1/16 in the first foot (1/2%).
You might try that and see what happens.

Co-owner of the proposed CT River Valley RR (HO scale) http://home.comcast.net/~docinct/CTRiverValleyRR/

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Posted by Javelina on Tuesday, March 19, 2013 9:07 AM

Hi Richard,

1/8" per foot sounds very reasonable. From what I've read, the formula for grade easements is similar to curve easement. As in curves, a reasonable approximation can be had using lath or other thin wood.

I'm also thinking about Linn Westcott's advice in "How to build Model Railroad Benchwork". In talking about grades, he pointed out that a layout should essentially consist of varying grades joining level areas where they would occur naturally for buildings and so on. Switch points count also. So maybe laying out the essential level areas and letting the lath show you the "natural" easements would work. Fasten a suitably long length to one level area and let it droop down to the next where it is again fastened.

Lou

  • Member since
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  • From: huizen, 15 miles from Amsterdam
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Posted by Paulus Jas on Tuesday, March 19, 2013 9:06 AM

hi Richard,

the above might help.

When you're building your layout with plywood cookie-cutter style, the plywood itself forms the easement; though you probably have to replace some joists.

( note: one carlength extra is added due to the turnout; and take your longest piece of equipment as starting point )

Paul

  • Member since
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  • From: Weymouth, Ma.
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Posted by bogp40 on Tuesday, March 19, 2013 8:58 AM

The amount of rise for the upeasing/ overeasing will vary with your grade. Generally,  the up easing should be at least 1 1/2 x the length of  your longest piece ( the length will vary w/ steepness of the grade). It will start at "0" and gradually rise into the grade. In spline or cookie cutter construction these easements will happen automatically as you bend the stock to the grade, very much the same as the "bent stick" method of easments into curves,  (keeping any seams/ splices at least one riser away) Foam and foam riser is a different story, you will need to cut, carve or place the foam/ risers to ease to the grade.

Modeling B&O- Chessie  Bob K.  www.ssmrc.org

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  • From: Central Vermont
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Verticle Easements
Posted by cowman on Tuesday, March 19, 2013 8:35 AM

Found plenty of information on easements for curves, but none for grades, but I know you need one, top and bottom.  I assume there is a maximum recommended rise per foot to get to the degree of climb you are after.  Does anyone know what that might be?

Is 1/8" in the first foot of change too much?  Should it start with more or less?

Have a friend that put in a grade and his 2-8-2 doesn't like the change in slope.  Does fine once on the grade.  Have no idea what his grade is.

Thank you,

Richard

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