Thanks for the update - when we were waiting for the ferry, someone said that was where Fat Teddy Killed Mary Joe - I thought they knew what they were talking about.
I drove to the bridge (Dike Bridge), I wanted to see it. It's not very long and basically takes you over an inlet called Poucha Pond that crosses to the beach. Back then you could take air from your tires and drive to the Beach. After dark, nobody would be there, Kennedy had his mind on bringing the gal to the beach for extracurricular activities, but he was drunk, driving to fast in a hurry, and as the bridge is narrow and at the time had no sides, it was not too difficult to drive off it.