Kniwt is right, it is legal from Novato to Mare Island at least. It is probably the fastest way to ride across the bay from Novato since you CAN'T ride on the SR/Richmond bridge. If you were riding for pleasure, this probably isn't the way you'd go, but for commuting, it's short length makes it very appealing. The "scary" factor depends on the time of day. The rumble strips are a pain to avoid, but they also give you a little more protection against cars veering into you, plus they give you a audible warning if someone's swerving towards you. If you travel this route early mornings or late evenings, there's not too much traffic. Just be WELL lit and keep you wits about you; if you hear a car on the rumble strips, be ready to MOVE. I don't go to Vallejo or the east bay that often, so I've not had the opportunity to ride this route yet, but I'll post here when I do and let cha know how it went.