o gage bridge approach

There is enough play in the track joints that this can happen. I don't know what brand of track you are using. I would draw a circle with a compass or use a stick to make one. Make the track follow the line.

if you measure your circle, how big is it at the center rails?

Sounds like you are trying to make a 180 degree turn using 72 inch diameter track with a 12 inch elevation at one end?  You laid out the track on a flat surface and everything lined up.  You elevated the track and the track was offset ?  The principle is similar to creating a grade with striaght track.  As you increase the grade, the length of track required to transverse the grade increases.   My suggestion also is to ease in and out of the grade both in elevation and radius to be successful.

It is gargraves which I have used for years,but never elevated,serious learning curve here. Thanks everybody !

WhenI layed it out it was true to gargraves factory sheet

do you have a picture of your area your working on?

And trying to rise 12 inches in that short a distance isn't making things any easier...

---PCJ

My error. The grade starts b4 the curve. I'm actually starting out at 4" then the o72 radii goes to 12" so I have 8"" in about a 8% grade I think. But I am really thankful for all the replies and great Idea's.Thank you everybody 

Not sure why your are going up to 12 inches.  If you can do less that would reduce the grade.  Ease the grade, for example make it 2-4-6-7-6-4-2 for an average of 5% maybe.  If you try to go in and out of a 7% grade with long length cars the wheels will lift off the track in the valley.    Also, ease the radius.  Use something larger than 072 in and out of the grade to reduce drag.

YO That is great info already know now that this isn't going to work will try your numbers. Thank you !!