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Brilliant barrier

On its 25th birthday, the Thames Barrier has a lot to celebrate. It is still looking good and operationally it is not showing its age. Alexandra Wynne heads to east London for an early birthday celebration.

Tomorrow it will be 25 years to the day that the Queen officially declared London’s Thames Barrier operational. Behind its iconic stainless steel cladding is a combination of great engineering and rigorous maintenance which could enable to barrier remain operational well beyond the end of its design life.    

The barrier was designed to last until 2030, but it is now conceivable that it could still play a part in protecting London from flooding into the 22nd century.

Not that this comes as a surprise to the man charged with managing the barrier, Environment Agency Thames tidal flood risk manager Andy Batchelor. He says the success of what he calls the “moveable wall of steel” is in part due to its simplicity.

We don’t take any component apart that takes more than six hours to put back together. If it is going to, we close the gate.

Andy Batchelor, Environment Agency

“Resilience and reliability are the two key words,” he says. “It was built using already proven, tried and tested technology. They didn’t use anything that was state of the art at the time and that philosophy has carried through to today.”

Although it is somewhat simple in its technology, the engineers behind it used great foresight and paid great attention to detail. There were 13,000 pen and ink as-built drawings for the structure.

Each of the barrier’s components has its own maintenance schedule and work is based on a “planned preventative system”, says Batchelor. The idea is to maintain or replace any component – not too early – but before it breaks down. As for the stainless steel cladding, it has never needed cleaning.

For the other parts, there is a strict “six-hour” rule in place, which means that the barrier can always be in an operational state. “We don’t take any component apart that takes more than six hours to put back together,” explains Batchelor. “If it is going to, we close the gate.”

To date, the barrier has been closed 114 times. And despite being on the project in various guises for all of his 30- year career, Batchelor says: “I still get a high every time we close.”

But he says it is a shame that the barrier is often out of the limelight. There have been no horror stories about a flooded London because the barrier has always done its job as it did during two of its closures in November 2007. That month stands out in Batchelor’s memory because it is a reminder about why the barrier was conceived.

I still get a high every time we close

Andy Batchelor, Environment Agency

The idea for a barrier gained momentum in 1953 when more than 300 people died after extreme weather combined with the tide to create a storm surge which flooded the east coast of England. In November 2007 another storm surge began sweeping inland causing damage and chaos down the east coast towards London.

“You could see it could be a replica of what happened in 1953,” says Batchelor. “But we had that great feeling that over 50 years on we have better forecasting and warning systems.

But if the barrier and its associated defences weren’t there, it could have been a repeat.” The Thames Barrier is the largest component of a bigger scheme, which includes other barriers at Barking and the King George V docks as well as 195km of flood walls upstream and downstream.

It may well have to accept a smaller role in protecting London and the surrounds of the Thames Estuary beyond 2030 as bigger flood defences are developed. But Thames Barrier will remain a star performer.

History

Serious flooding in London in the early part of the 20th century led to the development of the Thames Barrier.

  • 1928 14 die in London floods
  • 1953 Floods from storm surge kill 300 and destroy 24,000 homes and properties
  • 1954 Waverly committee recommends barrier to prevent flooding in London
  • 1966 Sir Herman Bondi’s review leads to the decision to locate the barrier at Woolwich. Charles Draper produces final design
  • 1974 Go-ahead for £230M (1973 prices) construction programme.Costain/HBM/Tarmac is the main contractor. Tarmac’s contracting arm is now owned by Carillion
  • 1984 Thames barrier officially inaugurated by the Queen     

How it works

There are nine concrete piers with 10 gates spanning about 520m from bank to bank.    

There are four, 61m long main rising sector gates that are over 20m high and 3,300t, two 31.5m long rising sector gates and four falling radial gates next to the river banks that remain above the river.    

Individual gates can be closed in 10 to 15 minutes but closing the whole thing takes 1.5 hours. This allows for equipment checks and stops the potential risks posed by reflective wave.    

The gates close in pairs from the outside into the centre and are rotated to closed mode from their resting position flush with the river bed. This protects central London from storm surges.       

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