Is it possible to make a bridge with two levels??
(https://www.sc4devotion.com/forums/proxy.php?request=http%3A%2F%2Fimg826.imageshack.us%2Fimg826%2F5150%2Fgoldenbridgemanhattanne.jpg&hash=e54e603f6a9bc22b1a5d819d55f23fed927a785a) (http://img826.imageshack.us/i/goldenbridgemanhattanne.jpg/)
It is possible, just look at jeronij's Tsing Ma bridge, but no one has found a way, yet, to make both hieths functional, although I think there has been work going on to try and figure it out.
Robin
The best way would be to use double-decked road, but this isn't out yet, nor in project so .. &mmm
First of all, this bridge isn't in New York nor it is called Golden [Gate], I assume you meant it. It's Bay Bridge is San Francisco ;)
Second, I'd like to add that you could easily build a normal highway/avenue/road bridge, then a subway tunnel below it and the connect the subway with normal rail ;)