This article was taken from the March 2014 issue of Wired magazine. Be the first to read Wired's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
Battersea Power Station's four chimneys are nearly a century old. Time for a refresh. "They're in quite poor condition," says Jim Solomon, a structural engineer at Buro Happold and a consultant on the £8 billion redevelopment of the site. The steel wads that reinforce the chimneys' concrete are corroding badly, which means all four 103-metre-tall stacks must be replaced.
Usually, the new funnels would be assembled off site and hoisted into place, but the power station's Grade II*-listed status prohibits this. "They have to be constructed as the existing ones were, using concrete mixed on the site and cast on a daily basis," Solomon says. "It's a fairly novel situation we have here." The painstaking process starts in March and will take five years. This is how it will work.
Bring out the lasers
To reconstruct the chimneys exactly, a laser will scan the inside of the southwest stack from a working platform at its bottom. The 3D model will form the basis of construction drawings for all four.
Line the chimney walls
Loose tiles that line the inside of the chimney must be stabilised. A rig will lower engineers inside, so they can first clean the surface, then line it with a temporary membrane.
Munch your way down
A self-climbing motorised rig uses hydraulic breakers with jaws to crush the chimney into 15cm pieces, which fall down a funnel. The rig works its way down the chimney, "munching" as it goes.
One goes up, three come down
Once the first chimney has been rebuilt to a height of 25m, the other three can then be simultaneously taken down. When finished, one of the stacks will contain a lift to a viewing platform.
Cast the new chimneys
Demolishing the chimneys will take five months. After that, a rig carrying a reconfigurable mould will cast the new chimneys'
1.22m-tall sections in situ. Each section will take about two days to set.
Hang the cradles
Once the casting rig reaches the top, it will be replaced by a maintenance system containing cradles for workers to paint the chimney. Navigation lights for aircraft and a copper lightning ring will be installed.
Cut it out and take it away
A 1.22m-high section of a chimney will be removed in one piece.
The rig (3) will crunch down to the level of the piece, and a powered wire-saw will separate it, allowing a crane to lift the chunk to the ground.
This article was originally published by WIRED UK
