Two things jump out at me: are there really that many bridges in need of maintenance in the Bay Area? Caltrans is making a big investment (e.g. Bay Bridge, Benecia etc).
I am also amazed at how much freight still comes into SF/Oakland and New York. Perhaps the "SF" traffic is actually Pittsburg and Stockton and I just can't see it clearly at this resolution.
The port of Pittsburg is teensy and the port of Stockton is specialized. Container traffic at Oakland is pretty heavy and many cars are offloaded at Vallejo. There are also the oil terminals at Richmond and elsewhere.
One note about the bridges: Basically, any elevated section of road seems to qualified as a bridge. That's why you can follow the interstates on the map; they're full of overpasses.
A lot of the NY freight is probably going into Port Newark-Elizabeth (Which is considered part of the Port of NY and NJ) but the resolution isn't high enough to show that. So there's probably not nearly as much freight going into NY proper as there looks to be.
I am also amazed at how much freight still comes into SF/Oakland and New York. Perhaps the "SF" traffic is actually Pittsburg and Stockton and I just can't see it clearly at this resolution.