Thanks for the quick reply Bob2. Passenger service over the Dumbarton right of way seems like a good idea. Even at inflated Bay Area construction costs, rebuilding that bridge (and double tracking) seems much cheaper than tunneling. Too bad CA HSR did not choose Altamont Pass and the Dumbarton route, but that's a new thread. Alas, things that seem obvious and a good idea in California (e.g., SMART, in my backyard, another separate thread), take too long and cost way more than projected / sold to voters. Enough for now, thanks again!