580 in Marin County was Highway 17 from 1958 till about 1990. It was upgraded to an Interstate as soon as Cutting Boulevard was upgraded to a freeway in Richmond. Its a good thing they did that. For a few weeks after the big Quake of 1989, Bay Bridge Commuters were forced onto the San Rafael Bridge and the San Mateo bridge, if they wanted to cross the Bay using a car. The Richmond San Rafael Bridge is about 40 years old.
Here I580 is approaching the bay in 1991.
This is the first sight of the bridge on I580 East.
The bridge starts out low and gets high in the center section. It is one of the taller bridges across the bay.
This bridge was used as a detour of I80 in 1989 after the quake.