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Superelevation

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  • Member since
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Superelevation
Posted by PDizzle on Tuesday, January 25, 2022 2:12 PM

I am building a new N scale layout.  I will superelevate the mainline curves.  Where the mainline makes a small turn (say a 15 degree turn) should superelevate the short curve or just leave it flat? 

If I transition the superelevation at either end of the curve, there isn't much space left in the middle, even with 20" radius curves.  Aside from operational issues, what is prototypical? 

Thanks for any advice. 

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Posted by 7j43k on Tuesday, January 25, 2022 2:45 PM

Superelevation doesn't happen just in the curve, but NOT in the straight.  It has to build up to its max height over a distance.  This "build-up" section usually shows up in the curve's easement, where the curve goes from being straight over to its true radius.

They kind of go together.

There will be a point where, based on the lengths of the easement, that the true radius never happens.  Suppose you have chosen a length for your easement of 12".  You might find that when the two easements, the "in" and the "out" are shoved together; you don't need any of the true radius at all.  Building on that concept, you might find you can get your curve by using only half of each of your easements.

This would mean that, because your superelevation is built into your easements, you might not get to full superelevation, but only rise up to a fraction of it before you start to come down.

That's all for the prototype.  And for people who like to model the prototype as closely as possible.

Model trains don't need superelevation.  So any you put is is just "art".  As long as you don't get carried away.

My point is, in this case, you can put as much in as you wish, and looks good to you.

If you are also doing easements, as it appears you might, I recommend going with what the prototype does, as described above.

 

 

Ed

 

  • Member since
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  • From: Wyoming, where men are men, and sheep are nervous!
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Posted by Pruitt on Tuesday, January 25, 2022 2:56 PM

I superelevate all my mainline curves, regardless of their length.

I start the superelevation about four to six inches away from the beginning of the curve, to reach maximum superelevation about six inches into the curve. The length of the superelevation is dictated solely by the length of the curve.

  • Member since
    February 2008
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Posted by kasskaboose on Tuesday, January 25, 2022 3:00 PM

Superelevation looks cool but I've not done it.

Here's a thread you might enjoy discussing the benefits of superelevation:

https://cs.trains.com/mrr/f/88/t/1603.aspx

https://cs.trains.com/mrr/f/88/t/1603.aspx

 

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Posted by jjdamnit on Tuesday, January 25, 2022 3:02 PM

Hello All,

You might want to take a gander at this thread...

Superelevation

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

  • Member since
    February 2005
  • From: Vancouver Island, BC
  • 23,330 posts
Posted by selector on Tuesday, January 25, 2022 5:31 PM

PDizzle

I am building a new N scale layout.  I will superelevate the mainline curves.  Where the mainline makes a small turn (say a 15 degree turn) should superelevate the short curve or just leave it flat?

I like main line running most and spend most of my time developing the main run and its adjacent scenery.  I won't have an unsupered curve on my main line.  The real rails don't, and neither do I.  I will admit that it sometimes seems more of a pain and an invitation to vexation with short curves, but they'll always look more gee-whizzy in photos and with your eye down near track level when you watch a train go through there.  Personally, it's worth the effort to me.  Once done, and running well with all rolling stock, it's always a source of pleasure. 

PDizzle

If I transition the superelevation at either end of the curve, there isn't much space left in the middle, even with 20" radius curves.  Aside from operational issues, what is prototypical? 

Thanks for any advice. 

 

If a curve is really sharp, the prototype reduces speed....AND supers the curve. Maybe not a full 5-6" difference to the outer rail as would be the case for 50+ mph speeds, but 3" or 2".  With yard speeds, there would be no point.  But since our layouts' mains are horribly compressed and full of compromises of all kinds anyway, why not go to the trouble to put a bit of noticeable super into even short and shallow curves?  It's not like you have forty other curves to enjoy the effect someplace.

If it's a very short curve, start the super transition well back, make it gradual, and then reduce it again after only a couple of inches of arc at the apex of the curve.  It MUST be gradual or you'll get derailments, and it will have to be very consistent...no undulations or dipping outer rail anywhere along this effort.

One other tip: you can mock this up somewhere, try to make it stiff and unbendable so that you have veridical results from trials, and then run all items, all configurations, trailing and shoving, at all speeds through this arrangement.  If it works well, and you can duplicate it faithfully on the layout, you should enjoy the effect tremendously...and confidently.

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