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Yes, I can hear the question forming on your lips: “Why are you talking about the Thames Barrier when June is supposed to be royal month, Mrs Nix?”  Well indeed.  But think back to that lovely royal flotilla we enjoyed on the telly a fortnight ago.  How come all those hundreds of barges managed to go in a straight line up a tidal river? Because this Monarch is the first one ever who can control the Thames’ tide, that’s why.  Once a year (usually in October), they test the Thames Barrier – this year it happened in June so the flotilla could float unimpeded. Relive the best bits here for those who missed it: http://www.youtube.com/watch?v=zHF7viVJnJg&feature=related

In some ways this is a great shame, because the Thames Barrier annual test is usually considered the main event rather than second spear carrier in the school play of life.   Let’s start with the science bit. The Thames Barrier was built over a period of ten years from 1974-1985 in response to a flooding which took place in 1953, drowning 300 people. It took a long time to design, because they wanted to find a design which (unlike the medieval London Bridge) would not mess about with the Thames’s own micro climate and would allow water traffic to pass through.  Eventually they happened upon the ‘silver sentinel’ design, so reminiscent of the nun’s scrum of the Sydney Opera House, and set to building it. It has been used in anger 85 times since 1985.  When it was first completed, they only had to raise the flood defences three times a year.  These days they are raised five times a year, and they estimate it will need to be raised 30 times a year by 2025.  The Thames has been quietly been going up by about 4mm a year, and so needs more bolshy management than once it did. Spouse says the fact that this great nation, and particularly the London end is slowly sinking into the sea can’t be helping (apparently our tectonic plate on which Merrie Olde Englande sits is on the move).

An hour and a half after I set off I was trundling through the retail and industrial parks of the deepest darkest East of London, and was clinging to my iPhone map app in much the same way as the man lost in the desert clings to his water bottle. Eventually I happened on signs to “the vista cafe and visitor centre,” and followed them relentlessly through the back streets and car parks until I hit my quarry: the famous silver sentinels standing guard over the river.  I was immediately unimpressed.  I took my photo at the top of a small mound, and overheard another lady saying the same sort of thing.

“I thought the silver things were supposed to turn around when the Thames barrier was raised,” said I.  “I know,” she said.  There was a pause.  “Still, good we’ve seen it,” she said. “Yes”, I said, deeply unconvinced. And off we set, both feeling obliged to have a proper look having travelled so long and far.  What I had not understood, you see is that it is not the big silver things that keep the river back in times of trial, it is some very boring but extremely large sheets of steel, all of which are attached to massive wheels which rotate when the flood defences need to be raised (they displayed a very helpful poster which explained).

I wandered down by the concrete walkway of the Thames path.  A very nice uncle helpfully explained to his nephew that there was a red line which showed the height of the Thames when it was unconstrained at flood.  It turns out that it is not really central London which is at threat as much as the Home Counties further up the river which are lower and form a flood plain for the Thames.  London and the Thames Valley is shielded by flood not only by the Thames barrier but a host of locks and other flood defences all the way up the river.  And as I walked closer and closer to the barrier, and saw a group of people being taken on a tour, and how ant like they looked as the wandered about the defences, I suddenly realised just how big the barrier is, and quite what a feat of engineering it must have been.  I overheard a security guard telling a man to walk to the other side of the barrier to see one of the barriers being lowered again.  I trundled across.

On the ‘sea side’ of the barrier all was complete calm.

On the ‘city side’ absolutely watery chaos had broken out, as water flooded tempestuously through the underside, and the seagulls congregated to eat the fish that were being flung to the top by the sheer force of the weight of water.  In celebration of the annual test, a large crowd had congregated to watch, and a member of staff had been prevailed upon to deliver a presentation, with microphone and dodgy loudspeaker.  As I approached he’d entered the q&a portion of his session, which was an unusually one sided affair, running something like this:

“Does anyone have any questions, any questions at all (long pause).  Don’t feel you have to ask a question, do let me know if there are any observations you’d like to make… (long, long pause).  That’s an excellent question! How high is the Thames Barrier? It’s (speaker cuts out) metres tall.  Any other questions that anyone wants to ask at all…?”

This went on for some time.  Looking at my watch I was sorry I couldn’t stay for longer.  I had neglected to go to the visitor centre despite it costing only £3, and I did not go to the Thames Barrier Park or the floating church either (we will eventually, but that day I had to dash back to west London to support the beloved at something completely different).  But fear not, we will return here, fair readers, because although engineering is not my first love, and it does take an inordinately long time to get there I do think that the Thames Barrier is a thing that one becomes more impressed by the more you learn about it, and that is a rare thing indeed.

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