Super elevation on a branch line

[airwolf crazy]

Greetings all,

 My new layout is a branch line off the Main line of the PRR in 1940 -50.  The branch is in a valley with access down the mountain and by the valley floor.  This branch is serviced by the PRR.  I cannot imagine that any of these trains will run at full speed as they would on the Main.

 My question is would the curves on the main branch line be super elevated?  If so, would they be elevated as high as the curves on the Main line?

My layout is HO, around the walls, and in a 10'x 16' room.  The min. radius is 22".

 Thanks,
Christopher

[johncolley]

By all means check out Joe Fugate's Siskiyou Line videos. His Coos Bay Branch coming through the coast range is slow moving but the superelevated curves are a thing of beauty! Watching 3 SD9's growl their way up the mountain and leaning through the curves is the most realistic modelling I have ever seen. Enjoy! John Colley, Port Townsend, WA

[dehusman]

airwolf crazy

My question is would the curves on the main branch line be super elevated?  If so, would they be elevated as high as the curves on the Main line?

Superelevation is based on speed.  Track of the same speed would have the same superelevation, regardless of main line or branch line.  The higher the speed the more superelevation.  If your branch has a speed of 45 mph then you might use 1/2 the superelevation on a 60-70 mph main.  If its only a 25 mph branch then the superelevation would be negligible.

[tomikawaTT]

Prototype superelevation is determined by three things: curve radius, intended track speed and Federal fiat (the FRA has rules which specify maximum superelevation.)

If your branchline has curves sharper than those on the mainline, it might very well have the same superelevation, even though track speed would be slower.  OTOH, if the branch has the same curve radii as the main but has a lower speed limit, then the superelevation would be less.

Model superelevation is purely cosmetic, but there is nothing that says, "Well engineered railroad," like a nicely superelevated curve.  In my own work, I superelevate about 1mm across the rails (or 1/16 inch measured at the tie-ends of Atlas flex.)  Superelevation increases from zero at the actual point of tangency to full at the actual point of curvature, in proportion to the tightening radius of a proper spiral easement.  Without such an easement, superelevation exaggerates the sideways lurch where tangent meets curve.

Chuck (Modeling Central Japan in September, 1964 - with eased, superelevated curves)

[airwolf crazy]

Greetings,

 Thanks for the replies.  I have now been told on two other forums that the lower the speed, the lower the elevation.  I also need to research PRR speed rules for branches.

 John, I do have Joe Fugate's Siskiyou Line videos and, of course, I totaly forgot about the small amount of elevation he shows.  I want to watch that again and see if that footage is the main or the Coos Bay branch.

Chuck, wow what an answer.  :-)  The Main line is off my layout.  A hidden staging and a fiddle yard are the two entry points (the rest of the world) to the main branch line.  The min. curve is 22" which I am sure is tighter than the Main but I get your point.  Flex track is being used so there should be some "natural" easement.  I have not done the calculations for easement as MR has published a few times.

I see I need a bit more research.

Thanks folks,
Christopher

[cuyama]

Easements will be much more important for reliable operation than will superelevation (which actually might negatively impact the model on curves that tight due to stringlining). If your interest is in prototype appearance, you porbably won't have room to run-off (decrease gradually over a distance) the superelevation very convincingly with curves that sharp on the model.

Not to say it can't be done, just that it's often tougher to make it look right in the model, IMHO.

Byron
Model RR Blog