I have no idea what the State plans to do with the old 520 bridge once the new one is done, but I suspect they plan to remove it.
I think we should turn it into a cross-lake park. Plant some grass, install a bike lane (even if it stops at the west end), put in some benches and picnic tables - then hope for some nice summer weather. Great place to walk, jog, or watch boats, people, cars and even the Blue Angels from a distance. Could even develop some access points to the park for boats.
NYC, Chicago, Philly, Paris and other world cities have turned old bridges, elevated rail lines and rooftops into parks. Check them out here: http://www.citymetric.com/skylines/here-are-all-city-parks-attempting-copy-new-yorks-high-line-695
Just seems a shame to tear it down. But I bet they will, and their reasons for not making it a park will make no sense to most of us.
BTW, as expected the state confirmed that they plan to remove the old bridge because it is “too dangerous to use.” Big deal. It would no longer be used by cars, so should be safer. If it’s too stormy, close it temporarily. If it starts to sink, demolish it. If not, enjoy it till it does sink. They also cite the boat clearances on the current high-rises. That of course would be easy to mitigate by removing the high-rises and accessing the “Cross-Lake Park” via the new high-rises.