Track transition curves


B

bennyboots

Noob model railroader
Have any of you modern railway guys ever expirimented with implementing track transition curves on your layouts. Like on the prototype railways?
http://en.wikipedia.org/wiki/Track_transition_curve
I would like to try this on my layout that I am building but maybe it is a bad idea? I like how trains look as they lean into a curve as they traverse it. In HO scale this would be the most minute angle maybe a 1mm lift around the corner. So am I crazy to think of doing this on my layout? What do you guys recommend?
 
Transition curves provide a lateral, or radial, acceleration into a curve. If you are on tangent track, and immediately enter a fully radiused curve, you would be thrown off your feet if the curvature were sharp enough and your speed high enough. So, a transition, or more properly an 'eased' curve, or simply easement, is a gentler way to transition between straight ahead movement and curving sharply right or left with that axis of movement added. It starts as a cubic spiral curve, at first just a slight shift from tangent to turn, and then you accelerate more gently to the point where the radial movement and tangential movement are evenly matched. Soon enough, an opposing cubic spiral softens the transition back to tangent-only movement.


Do they help on our scale track systems? Yes, some...a little. Do they look good? Yewbetcha, right up there with superelevation.

Mikadowithsmoke2res.png
 
Transition curves provide a lateral, or radial, acceleration into a curve. If you are on tangent track, and immediately enter a fully radiused curve, you would be thrown off your feet if the curvature were sharp enough and your speed high enough. So, a transition, or more properly an 'eased' curve, or simply easement, is a gentler way to transition between straight ahead movement and curving sharply right or left with that axis of movement added. It starts as a cubic spiral curve, at first just a slight shift from tangent to turn, and then you accelerate more gently to the point where the radial movement and tangential movement are evenly matched. Soon enough, an opposing cubic spiral softens the transition back to tangent-only movement.
Click to expand...

You know too much stuff for your own good u know... :D
 
Actually, with easements, you can run locomotives into radii that are tighter than recommended. They may not look good with excessive overhang, but at least they stay on the track.
I know there is a formula for easements but laying your track out by eyeball engineering, you can come pretty close. It's basically a principle of a tightening curve where the initial few inches of the curve are very slight but the radii decreases as you go further into the curve, i.e. starting at 2,000" radii for the first inch of track reducing to 1,000" radii the next few inches and continuing on down to the objective 36" radii. Some layouts may not have the room for this kind of engineering so it is more of an incentive to look for the opportunities to expand your right of way. As Selector's picture illustrates, this is much more appealing to the eye than a sudden, roller coaster type turn that a lot of layouts are forced to employ using snap track.
 
Benny, you start by discussing 'easements' but then reference angles and leaning trains which implies super elevation. Both are useful in modeling, but go really easy on super elevation. It doesn't take much.
 
Some track design programs like Xtrakcad have options to do easements in the design. I started mine that way but with my limited size I had to remove them.
 
Yes, super elevation can be achieved with just a thin piece of cardboard under the outside edge of the cork roadbed. Ya need to line it up so it is directly under the outside rail of the track. Running a belt sander over the installed cork roadbed is another method but ya can't control the amount of lean as well as putting materiel under the cork.
 
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