I got stuck on the non-downtown side of Shanghai once because I assumed that I'd be able to walk or bike across at least one of the bridges. But I couldn't find any way to get across. I had to wander around until the metro opened back up in the morning to get back across (and make it to flight in time).
When i first visited Shanghai in 1989, there were no bridges or tunnels between the Bund sid eof the river and the Pudong side, only the ferries. (pudong was mostly farms.) The ferries are less used now, but there are still some in operation, incluidng some that run 24 hours a day:
