Quote Originally Posted by renf View Post
I believe I have seen references to early versions of architectural drawings for the bridge across the Straits of Mackinac. One version, I think, had a deck designed for rail traffic....
From Wikipedia:
The preliminary plans for the bridge featured a 3-lane roadway, a railroad crossing on the underdeck of the span, and a center-anchorage double-suspension bridge configuration similar to the design of the San Francisco – Oakland Bay Bridge.