They have a port authority who will drive your vehicle across the bridge for you. That one is the Mighty Mac. One one side of it is Lake Huron and on the other Lake Michigan.
http://www.iment.com/maida/family/paul/rvtrip.htm
We had the RV prepped for months before we left. A gentleman from TX came with a dish in his trunk so that we could communicate TO the web, as well as receive. There were 5 separate workstations built into the walls so that we could settle down in multiple places to be on the computers. Paul had built me my first digital video editing setup, so I did that while he spent his time searching the internet for lower bridges with higher guard rails. It really was all rather funny. When we finally got back, someone had to park it for him in the driveway, and it’s never moved since that first trip. I consider it a house addition.