It would require a bridge that allowed a sailboat to get under it. The bridge that used to be there was a temporary bridge used to trolley military supplies back-and-forth between the Dorchester Armory, and the now defunct Squantum airfield. It was destroyed soon after World War II. Squantum airfield is now known as Squantum point park so that’s another thing that would make your idea impossible, creating a new roadway through a park would be in violation of mass general laws, article 97, which prohibits construction in designated Parkland, without special legislation.