Sketching Without Lines

I continue to try to use watercolors without an underpinning of a line drawing, mostly without success.  I can’t seem to figure out how to draw crisp edges with watercolors and, for complex drawings, I lose control over the drawing itself.  This is a good example of both of these problems.  This is a drawing (??) of a new pedestrian bridge over my river.  Great bridge, not so great sketch of it.  I added some pencil line buildings after the fact just to provide context.