... was almost replaced with this contraption:
For the love of God, it's eating the machines!
The goal of the Tower Bridge's design was to allow both road and waterway traffic to pass through, and while the elegant drawbridge it eventually became may seem like the obvious solution, it managed to elude everyone in the United Kingdom for a while. So one idea was the "duplex" bridge pictured above, which would split in two to allow one road to always be open while water traffic passed beneath it (this is ignoring the fact that both roads stretched over the same waterway).
Another was to dig a tunnel beneath the river, which doesn't seem unreasonable until you consider that this was suggested in 1876, back when a bridge tunnel was exactly as possible as lashing your coach to Pegasus and flying across the Thames.
Via Daily Mail
Just think of how many orphan laborers this project would've claimed.