I'll raise (No, I am not sorry for that pun.) you the
Bourne Railroad Bridge that spans the Cape Cod Canal near Buzzards Bay. I took that in 2016 as we exited the Canal on our way from Boston to Marion where we were to drop the boat off as we were the delivery crew. According to my navigational charts, it has 500 feet of horizontal clearance and 135 feet of vertical at mean higher high water. Since it's a railroad bridge, it spends most of its time in the up position. Occasionally careless types
hit the span causing much mirth amongst those who know how tall their boats are and the state of the tide.
3 types of channel bridges -
1 the lift aerial version pictured
2 draw bridge where one side pivots up and out of the way
3 swing bridge in the middle of a wide channel (would not work here too narrow a channel)
I'll add a couple more:
4. Double-leaf Bascule bridges where there are two movable spans that join in the middle to bridge a channel.
5. Side-draw bridges. These are largely obsolete now, but there used to be on in Boston where the movable portion of the span was on rails so the span could be opened by moving it diagonally in relation to the fixed portions to clear the channel.
There used to be a magical spot (at least magical to the engineer) on Boston's Fort Point Channel where you could see all at once save for having to turn one's head. Most are gone now, victims of progress, but when the side-draw bridge got replaced the made it up to look very much like the original save that now it's all fixed-span. Here's the "
"side-draw" replacement bridge showing the rails upon which once rode the moveable spans. If one scrolls northeastward in the image towards the harbour, the next bridge used to be a top-mounted-counterweight Bascule, the next one is very new, and the final one is a swing bridge that's now sadly rusting away in a permanently-opened position.
