I traveled to Australia to give several workshops on ERDAS IMAGINE that included basic Image Processing tools, Photogrammetry and 3D Visualization. One of the questions that I was asked during a presentation was "is it possible to create bridges in 3D?". At the time I answered "no, it is not because the elevation data would not allow it and you can't see what is under the bridge from the perspective of an aircraft".
On my plane ride home I did some thinking and figured out a methodology to include bridges in an 3D environment using photogrammetry, 3D feature extraction, making some graphic and raster edits, and then including that in a 3D visualization environment. 
This is the result.Here is the fly through!
