At the rate the sea level is rising, UP is going to have to do something about Elkhorn Slough fairly soon (institutionally speaking - within 25-50 years). Caltrans and TAMC would still like to do the Prunedale Bypass, some day. Why not get the bunch of them together to build a new freeway with a railroad line in it, similar to the 138 (High Desert Corridor) project near LA. All you need is money ... though IMO a better place to throw tunneling and relocation money in the short term is LOSSAN past San Clemente and/or between Sorrento Valley and Old Town.