If I remember correctly, once a hurricane evacuation is declared, Route 3005 (aka Seawall Blvd) is turned into a one-way road headed toward I-45 and the causeway. So I doubt your solution would work for my sister -- expecially since she lives on Tiki Island (between Galveston Island and the mainland, just north of the causeway). And she couldn't leave early, because she's a surgeon at UTMB and I don't think the hospital decided who'd be E-1 until Wednesday.