I'm not even sure what you're talking about then, because Disney Way doesn't have a bridge or even a proposed bridge. Also none of this goes across Anaheim Blvd either. So I really think you have your streets mixed up here.
Also we have a recent example of how long a parking structure and pedestrian bridge will take with Pixar Pal and its bridge, as it was completed within the last decade. Even using your example of the DTD bridge, that didn't take more than 18 months if I recall correctly.
Bottom line I don't think the EGW Pumbaa structure and the Harbor pedestrian bridge will take much longer than 18 months from start to finish. Other stuff with the EGW project like monorail realignment and such may take longer, but not the actual parking structure and bridge, in my opinion anyways.