Bridges symbolize transitions in life. Whitney had some place to go when she had this dream, some huge transition to make (the GW bridge is a BIG bridge) in which she had to leave the old behind and enter a new phase in life. She was afraid to do it, however, especially since she could see that the transition would take courage because it would be rocky and swaying. Crossing over those emotional waters is often so painful that we'd almost rather stagnate in a bad situation rather than go forward toward a solution. I bet she's made it across by now, though, and has dealt with those fears.