I'd say your contours are pretty good overall.
What I'd do is push the foreshortening more, especially on the top loop there would be a pretty hard kink in the cylinder. I tried to make it flow more evenly and pushed it a bit further away from the viewer, looks more like a fluid motion to me.
The other thing I noticed is that it didn't look like you drew your ellipses all the way through. A lot of them look like they should be more rounded on the borders of the tube.
And one last minor thing. Make sure the left "railing" of the bridge is the same height (or even smaller, considering there would need to be space for the floor) as the right side.
Aaaand another thing that came to mind while writing: Probably could have pushed the sitze of the tail at the bottom due to perspective (Circles in blue).
Keep it up, I love you work =).