Artist's rendering of what the completed bridge will look like. Note the light rail trains running to the right of SR-520. Presumably the bridge is being constructed to accomodate the planned Link Light Rail expansion to the East Side of King County. Note also the red circle on the side of building 43. That's my old office, which provided for a great view of the project. Rendering taken from the City of Redmond's web site.
From Bridge Construction