# Banked Curves



## Bill4373 (Jan 3, 2008)

I am building a new layout. I am considering banking the curves by increasing the height of the outside rail by 1/8" for about 8 feet and then another 1/8" into the curve so the outside rail curve would be 1/4" higher than then the inside rail.

Any ideas, concerns, etc.

.


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## JackM (Jul 29, 2008)

Bill - 

In Fall, 2009, when I was just getting started in G scale, I asked about banked track. You might be able to find them by searching for "superelevated" in this forum. Or perhaps in the Beginner's forum. 

From my early experiences, I'd suggest you go very slow. Even with my minimum curves at 16 ft. diameter (okay, I sometimes cheated a bit), I found that some of my curves would bank themselves if I wasn't paying attention when bending the rail. As a result I had to re-do some that simply looked toooo banked. Race cars look good on a NASCAR banked oval, but trains are relatively much taller. It doesn't take a lot of tilt before it takes on a toyish quality. 

On the other hand, a Bullet Train would look very cool..... 

JackM


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## Greg Elmassian (Jan 3, 2008)

I'd normally ask you what radius, but let me tell you, it's a bad idea... it can be done, but the vertical easements, and the poor suspension systems on most large scale locos. 

Now, correctly done, and carefully done, and with large radius curves, and locos and cars with good suspensions, it can work. 

Regards, Greg


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## rpc7271 (Jan 2, 2008)

I've banked a lot of my 16' dia curves. I have used LGB #18000 curved sectional track and LGB flex track at about a 16' dia. All of my roadbed is poured reinforced concrete. To bank the curves I have cut 1/4" x 1/4" balsa strips. The strips are glued to the concrete roadbed with silicon caulking. The strips are located under the outside rail and not at the edge of the ties. This location helps protect the balsa from the elements. When glueing the strips down they are hald in place by putting spare bricks on them to hold them in place for 24 hours. The balsa strips are then sanded for a smooth grade and the end ones are sanded from 1/4" to nothing to form a smooth transition from level section to a superelevated section. The track is then glued in place by filling the hollow space in a tie every 6" with silicon caulk and weighted down with the same bricks previously used for the balsa strips for 24 hours until the caulk sets up. The flex track is easier to place superelevate than the sectional track. Because the sectional track is designed to be used level when you place it superelevated it tends to fight you because it is less flexable. Please note that this method works because I have concrete roadbed and can glue everything in place. I have had superelevated curves on my RR made this way for over 6 years now with no problems. The balsa strips are as good as when I placed them. The trains sure look neat going around those curves.


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## NTCGRR (Jan 2, 2008)

I had them on 20' dia for a year or so and it was not worth it for long trains. plus you don't really notice it unless your looking straight on. 
just my thoughts.


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## Greg Elmassian (Jan 3, 2008)

Marty, can you go into the problems that made it "not worth it".... I think the information would help... not a lot of people have experience with this. 

Greg


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## Chris Scott (Jan 2, 2008)

*banked/super elevated raised track? *



03 Mar 2009 04:05 PM

Some time back a G1MRA member wrote a Super Elev. tech analysis for the G1MRA Journal&Newsletter. Conclusions; 1. The effects do not scale; 2. SE of no benefit in our scale; 3. Can cause excessive wear to wheels/rail. I believe the scale calculation resulted in a 1-3 degree elevation. 

The other curve mitigation method (other than larger radius curves) is curve easement. Easement seems to me the better solution than SE. Easement may reduce the curve radius a little, if your maximum space is limited, but the benefit to running would be worth it.


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## aceinspp (Jan 2, 2008)

Any time you are going to use super elevation you must remember to use spirals approaching the full body of the curve. This entails adding a gradual rise in elevation at the very start of the curve. It is not done on tangent track. Basically this why it does not work well in scale RR. The effect and benefit is not worth all the calculations and it would be so minimal. As our trains do not have the necessary suspension this also contributes to problems of derailment. Later RJD


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## Bill4373 (Jan 3, 2008)

This is my 3rd layout following the concept by Chuck Walters, Nov/Dec 2002, Steam in the Garden magazine, except the cross boards are composite boards, using a 20 feet diameter, code 332 track. 

So the whole track would be on the same "plane" not putting sticks under the outside rail. The last 8 feet straight section would be raised 1/8" on the outside and then the first curved section would be raised another 1/8" on the outside, thus making the outside edge of the composite boards 1/4" above the inside composite boards with the rest of the curved sections being at the same plane with the previous curved sections. Then reversing them upon the completion of the curve.
.


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## chuck n (Jan 2, 2008)

My thought is that unless you are running your trains at very high speeds, scale 70+ MPH, you really don't need super elevation (SE). At the speeds most of us run our trains, there is a problem with them falling off the track on the inside of the curve if there is any super elevation, especially if the curves are tight and the train is long. The purpose of super elevation is to keep the train on the track at high speed when going through a curve. Like the banking of corners at a race track allows the driver to maintain speed without flying off. We just don't achieve the speeds necessary to require the SE. That is unless you are running an Acela through LGB R1 curves at scale speeds.

I have been at some train shows where the Lionel layouts could have used SE, as their trains were going at multiples of their maximum scale speed.

Chuck


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## Bill4373 (Jan 3, 2008)

I received enough replies off-line that I'm not going to bank the curves.....appparently not worth the effort...thanks for the input

.


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## Semper Vaporo (Jan 2, 2008)




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## Greg Elmassian (Jan 3, 2008)

Funny! Like you cannot "bank" the track because it won't fit in the ATM deposit slot... 

Greg


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## Doug C (Jan 14, 2008)

"...trains were going at multiples of their maximum scale speed..." 

The times I see any MR train going that fast I just call them all ---- "lionel" !! 


imho, 
doug


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## Madman (Jan 5, 2008)

I don't see the argument for *not* banking curves. If someone wants to bank curves, why not. When I had my Lionel Hi-Rail layout, in the basement many years ago, I banked the 072 curves 1/4" on the outside rail. Looked great with the GG1 pulling a string of passenger cars at high speed. And I doubt that it wore any of the wheels in excess. In fact, I would think the opposite. It also allowed me to run at high speed throughout the entire layout. So go ahead and *Bank away*.


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## Greg Elmassian (Jan 3, 2008)

The arguments/warnings were already listed above. What you are doing is creating a cross level / warp situation. Done right, with easements it works, but not all of our models have suspension systems that can handle this. Most people who have tried it have had problems. 

I volunteer you to test it out ha ha! 

Greg


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## Madman (Jan 5, 2008)

As a matter of fact, I have tested it, as I stated with my Lionels. They have no suspension. Our large scale trains have more suspension just in the truck play. It doesn't take much engineering skill to super-elevate a curved section of track, no matter the scale. Just some common sense will do just fine. I don't feel that someone should be told not to do something that they want to do. Let the experimenting go on. It's the best way to learn and maybe come up with some new ideas.


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## Greg Elmassian (Jan 3, 2008)

He asked for opinions... he got them... 

Your lionel trains have huge flanges, short wheelbases and were built for extremely tight curves. Most G scale stuff is not that "hearty"... So go ahead, like I said, I volunteer you! 

Not everyone wants to experiment, I read the forum for years and took in a lot of advice before I ever posted or laid track, and I'm glad I took the consensus of opinion. 

Again, not saying it's impossible, but it's not a slam dunk, you have heard from people that have tried it. 

Greg


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## Madman (Jan 5, 2008)

I've already volunteered myself, way before this topic ever came up in these forums. Some curves on my railway are banked. I've run large and small locos and cars. Never had an issue. I too read all about garden railways in journals. However, I learned more by doing than by what others wrote. But that's my way of moving ahead. Like I said, some of us need the written word to proceed, others of us need to see it in the flesh.


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## NTCGRR (Jan 2, 2008)

Been busy. 
I stopped doing mainly because ,as I said, you don't see it unless your at the right spot. then if you had a long train stopped on it, it would string line a few cars because even 20' dia is too sharp compared to real trains. 
Next would be where to start the bank for the longer engines. the Dash-9 s have a less forgiving frame and one wheel would ride up on the outter rail coming off. 
Like I said , it just was not worth the effort. Someone else may think it is. 
level(side to side) insures better running. 

Just finished my 2nd 1" scale switch last night. all my 4 3/4" track is level side to side.


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## Madman (Jan 5, 2008)

Example of nicely done super-elevated curves; 

http://youtu.be/Q7ML7X0WA-U


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## Greg Elmassian (Jan 3, 2008)

Not to get into an argument, but watching this, you can see the abrupt transition into the banking where the car quickly and sharply heels over. Does not look realistic to me, and I doubt you could run long trains through something like this. 

But to each their own. 

Greg


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## Madman (Jan 5, 2008)

I thought that I *was* watching a long train run through the curves, in the film. I'm not trying to raise an argument, but I fail to see what the issue is with building these curves. The train goes into them nicely, without any problems. Everything looks nice to me. Then, I am not a rivet counter.


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## Semper Vaporo (Jan 2, 2008)

I AM a 'Rivet Counter' and the superelevation in that video looked just fine to me. The curves are much too sharp, but what superelevation there is in them is smoothly transitioned from/to the tangent tracks. There is one place where the track seems to have "tented" but that was on a tangent track just before the long bridge, not associated with curves or superelevation.

I TRIED to superelevate my track, but because I let my track float in the ballast and because my track was so light it would not sink into the ballast but would "rise to the top" after I poured ballast over it after a train had passed over it a couple of times -- any superelevation I tried to force the track to conform to soon disappeared or would sometimes invert to be the wrong way (sub-elevated? Supra-elevated?). When the track would take on a superelevated state all on its own due to thermal expansion and ballast settling (and birds eating the balast!) the effect was pretty nice to see.


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## Chris Scott (Jan 2, 2008)

1. A prototypical superelevation scaled to Gauge One (1:32, nominal =>15' radius curve) would be so small/little as to be visually undetectable. 


2. A Gauge One (1:32, nominal =>15' radius curve) visible superelevation would scale to a prototypical superelevation which would cause the train to roll over, or depending on speed resemble a velodrome.
Compact Version: 
RE: Modeling true-to-scale superelevation: 1.) If it's real it's not visible; 2.) If it's visible it's not real.



As long as the above two axiomatic formula results are accepted without equivocation or objection, then bank your curves to your hearts content, as much as you want and for beauty in your eyes.


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## Totalwrecker (Feb 26, 2009)

You scale an angle? Say a typical superelevation creates a 1 degree angle off perpendicular, wouldn't the angle still be the same in scale? 

I allow superelevation to happen as I sculpt my right of way with sectional track floating in ballast. I use 1/8th " as an offset, I like the hint of a lean as my choochoo digs into a curve.... 

Happy Rails 

John


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## Semper Vaporo (Jan 2, 2008)

The (U.S.) FRA max superelevation is 6-inches, but it is seldom over 3-inches.


A forumla used to calculate superelevation is:

Superelevation in inches = 4 * speed * speed / radius

60 mph on a 4800-ft radius curve results in 4*60*60/4800 = 3-inches.

Just to PLAY with some numbers....



In 1:32 scale that is equivalent to 150-ft radius with a superelevation of 3/32-inch.

Typical 1:32 scale curves are a whole lot less than that! Reverse the process, assume a 7-ft radius in 1:32 is then a 224-ft radius prototype.

Fat chance you'll get an SD90MAC to go around that curve and stay out of the dirt but plug it into the original formula:

60 mph on a 224-ft curve: 4*60*60/224 = 64.28-inches... UHHHHH..... That is 5-FEET,4.28-inches! Standard gauge is only 4-ft, 8.5-inches! That SD90MAC is on its side sliding between the rails!

How about a 20-ft radius? 20*32 = 640-ft prototype radius ... 4*60*60/640 = 22.5-inch superelevation!

How about a 40-ft garden radius? 40*32 = 1280-ft prototype radius ... 4*60*60/1280 = 11.25-inch superelevation!

How about a 80-ft garden radius? 80*32 = 2560-ft prototype radius ... 4*60*60/2560 = 5.625-inch superelevation!

How about a 150-ft garden radius? 150*32 = 4800-ft prototype radius ... 4*60*60/4800 = 3-inch superelevation!


Just playing with numbers to see what happens.


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## NTCGRR (Jan 2, 2008)

Heres one photo of the south banked curve. you can see it in the hopper. But unless your camera is level and in the currect spot you can't tell its half bubble.


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## TheFishGuy (Feb 1, 2011)

Posted By Semper Vaporo on 02 Dec 2011 10:57 PM 


The (U.S.) FRA max superelevation is 6-inches, but it is seldom over 3-inches.

 
A forumla used to calculate superelevation is:
 
Superelevation in inches = 4 * speed * speed / radius
 
60 mph on a 4800-ft radius curve results in 4*60*60/4800 = 3-inches.
 
Just to PLAY with some numbers....
 
 

In 1:32 scale that is equivalent to 150-ft radius with a superelevation of 3/32-inch.
 
Typical 1:32 scale curves are a whole lot less than that!  Reverse the process, assume a 7-ft radius in 1:32 is then a 224-ft radius prototype.
 
Fat chance you'll get an SD90MAC to go around that curve and stay out of the dirt but plug it into the original formula:
 
60 mph on a 224-ft curve: 4*60*60/224 = 64.28-inches... UHHHHH..... That is 5-FEET,4.28-inches!  Standard gauge is only 4-ft, 8.5-inches!  That SD90MAC is on its side sliding between the rails!
 
How about a 20-ft radius?  20*32 = 640-ft prototype radius ...  4*60*60/640 = 22.5-inch superelevation!
 
How about a 40-ft garden radius?  40*32 = 1280-ft prototype radius ... 4*60*60/1280 = 11.25-inch superelevation!
 
How about a 80-ft garden radius?  80*32 = 2560-ft prototype radius ... 4*60*60/2560 = 5.625-inch superelevation!
 
How about a 150-ft garden radius?  150*32 = 4800-ft prototype radius ... 4*60*60/4800 = 3-inch superelevation!
 
 
Just playing with numbers to see what happens.


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## chrisb (Jan 3, 2008)

I find it interesting what was stated previously about using a spiral curve for the transition. The spiral is a curve which the raduis goes from infinate(straight) to the radius of the circular curve (20 foot for example) to be used or evetually zero. 
Its been along time since I dealt with sprials and they were on the interstate and not rail.


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## Greg Elmassian (Jan 3, 2008)

Interesting, since most modern highways use constant radius curves with very little or no transitions. 

Country roads, and onramps will often be spirals. 

The reasoning on the highways is simple, when you think about it, and you can prove it to yourself. 

Regards, Greg


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## noelw (Jan 2, 2008)

We bank most of our curves using a Train L binder to get the approx curve a little larger than what we want and then pull tracks in a little. That will make an easy bank. Then we ballast with sand and mortar to hold its shape of you curve. Making a transition curve work great, but not with section track from a straight to a curve track, that doesn't work well.......This little bank is OK here with Dash 9's and hwt. pass cars so far. 

This is what we do and it becomes a natural curve with a slight bank.

Get a chance..... watch the middle of this video to see Train coming in to a curve. Works for us., but like Marty said if you aren't down at the level of the train it doesn't mater anyway. 

http://www.youtube.com/watch?v=eos4VufcRQs&feature=related


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## rpc7271 (Jan 2, 2008)

All interstate highway curves are superelevated and have a spiral cure at the entrance and exit of each curve except for anything curve less than a 1 degree curve per AASHTO (American Association of State Highway & Transportation Officials) standards. Most curves on state owned highways will also meet this requirement also. By the way the RRs invented the spiral curve and were the first to use them.


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## Greg Elmassian (Jan 3, 2008)

All I can say is the spiral is very short... when I come into a turn, I turn the wheel and hold it steady through the entire curve. If it was not a constant radius curve this would be impossible. The very short time taken moving the steering wheel from straight to a fixed position in the curve means that either the transitions are very short, or maybe it's a side effect of going 85 mph. 

I don't doubt there is some short easement, but it's not extensive like what we try to do when we have enough room in trains. 

Greg


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## Totalwrecker (Feb 26, 2009)

Greg, we've been here before. Remember I asked if you snapped your wheel to that constant curvature or do you ease into the curve. Yes roadway spirals are shorter, rubber is more responsive than steel on steel. 
Our toy train easements are longer due to poor tracking by ridgid wheel bases and lack of mass to keep them pressing into the track. For me super elevation helps mute the snap turn of sectional track. 
Happy Rails and Seasoned Greetings 

John


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## Greg Elmassian (Jan 3, 2008)

Yep, I think we both agree, there are spirals, and they are short. 

Completely agree on all points you made. 

Greg


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## Cougar Rock Rail (Jan 2, 2008)

I really like the look of banked curves, but you have to be careful where you apply it for the reasons outlined by others above. Here is a picture of a spot on my layout where the track is slightly banked. I didn't even try to do it on purpose, it just naturally wanted to do it so I left it and it's now one of my favourite spots to watch trains on. BTW, I'm using LGB 3m flextrack and bend it with the Train-Li bender:


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