SR 520 Portage Bay Bridge Extradosed design concept - Portage Bay and Roanoke Neighborhood from Montlake Playfield
This hybrid of the box girder and cable stay designs uses towers and cables to support a span over the bay. This is lighter on the environment, thinner, and creates less shadow than the girder type. The towers are shorter than a cable-stay. The cables and towers are more visible than with a girder bridge.