Spiral Curve

[laveyb24]

I have been asked by a co-worker the best way to solve this problem but i am not familiar with spiral curves. I am hoping someone with more experiance in this area can help me out and let me know a good way to solve the spiral. The document reads as follows.



Thanks,

[TTaylor]

There are different types of spirals out there. However, if you look up spirals in Route Surveying and Design" by Meyer and Gibson or "Surveying" by Davis and Foote you can find hard to read write ups.

I am looking through my old notes for my write up of a simple step by step calculation method I used for Caltrans. So far I can't find it (drat). I'll keep looking.

FYI, you are dealing with a differential.

[Steve Martin]

It looks like the deed is referring to a Taper Curve where the degree of curvature is changing by 30 minutes for each 33' chord length.

I beleive that Tapers are usually based upon 30' chords, at least on the Southern Pacific line.

Do you have a copy of the Railroad right of way plat?

We have covered Taper curves on this forum before. I'll look at home tonight to see if I still have the old SP Taper Curve tables.

[Jim Frame]

As Tom Taylor noted, there are many ways to skin this cat. The trick is to figure out which was used by whomever you're trying to retrace.

I've attached the SP taper curve booklet that Steve Martin referenced.

Are you interested in track curves, or ROW curves?