Interesting! I wonder if the pan being flared out (instead of being cylindrical) effects the shadow? I've driven around the Durango curve many times, but my observations were always pretty casual.
Rick
I believe so too, but how do we prove it? It must have something to do with the projection of the circular barrier onto the freeway. A special case would be when the sun is directly overhead. Then it would be the quadrant of a circle (special case of an ellipse).
Other thoughts are:
1. It is a...
This is one I haven't worked out a solution for yet. It's probably not too hard. Hopefully someone can provide a clear explanation. http://rickmckeon.com/mathfun/puzzles/The%20Durango%20Curve%20Problem.pdf
rick123