There are three very similar swing bridges over the Caledonian Canal here in Inverness – two road bridges and one railway bridge, all working on the same principle and constructed around the same time. Yesterday I was passing by just as the bridge at Tomnahurich opened, so stopped to capture the scene on camera .
The road crosses over from left to right of the picture (or right to left, depending on the direction of travel) and the bridge sits really low on the water so boats travelling the canal cannot pass underneath without the bridge moving out of the way. The traffic is temporarily stopped on either side and the entire bridge swings open sideways on a pivot and wheel (very much like a giant heavy door opening) until it sits at right angles to the road. The boat sails on through, the bridge closes again immediately, and the waiting traffic is free to pass over once more.
During the summer months this process takes place multiple times a day, and it never ceases to fascinate me – I really love the clever engineering involved! There is a warning siren that sounds continuously to let people know the bridge is opening and closing, but amazingly the mechanical operation of the bridge itself is silent and smooth and surprisingly speedy – it only takes a few minutes. This particular metal bridge has been in situ since 1938, a replacement for a previous wooden bridge that apparently worked on an entirely different principle.
I know this is a long and boring gallery if you’re not interested in seeing a series of static images of a bridge opening and closing again, but the fault is mine for not thinking to video it in action instead – duh! Anyway, I’m hoping my swing bridge opening and closing can count as an honorary canal door for today’s Thursday Doors – I know Dan loves bridges as well as doors, so fingers crossed I might just get away with it! 🙂