If its freight trains you're after, you won't find many in the immediate Bay Area. Your best bet is to take Amtrak out to Stockton and walk three, or four blocks down (East) Hazelton St to the crossing. Not a great neighborhood, but during the day it is okay....I've done it several times without problems. There is a nice park with views of the crossing where you can get out of the sun. August will be hot in Stockton. You can walk from the park to the former Espee station, catch a San Joaquin to Sacramaento and return to Emeryville on a Capitol, making a circle and not retracing your steps. The activity at the crossing is very intense and it is far and away the best place in Northern California for freight trains, available by using public transportation. There is also a free jitney that circles downtown Stockton and stops at both the former Santa Fe and Southern Pacific stations.

By the way....the Barnes and Noble at Jack London Square has closed.