ABU DHABI // Spotting 3,500 tonnes of oxidised mild steel should be easy, but when it comes to the Louvre Abu Dhabi construction site nothing is quite what it seems.
"It's like an iceberg," says Shehab Taha, the project's senior construction manager. "You look at the dome when you cross the Saadiyat bridge, but everything is below and you cannot see any of it."
From a distance, the museum's canopy already looks like it is hovering above the galleries, but that is because of 118 temporary towers, 500 trusses, 30,000 metres of beams and 17,000 square metres of platforms and scaffolding supporting it until its completion.
In construction terms, this forest of steel is something of a mirage. Once the finished canopy has been lowered on to the four giant steel bearings that will eventually support it, all of this infrastructure will be dismantled and recycled.
"The temporary towers are a construction project in their own right," Mr Taha explains. "There is close to 5,000 tonnes of steel in the dome. The amount of steel in the temporary works – which will be removed and not used – is close to 3,500 tonnes. It's like you are building another dome below the dome."
More in keeping with a shipyard than a museum, the temporary towers cannot be seen from Louvre Abu Dhabi's perimeter but they can be heard, and like the pipes of some massive organ, each element sounds with its own discordant note.
Overhead, teams of harnessed workers lower roof beams on to trusses with a repeated hollow crash, while somewhere in the bowels of the site unseen workers beat metal with metal, producing a ringing that vibrates through the chest.
The team installing temporary tower 91 seem oblivious to the noise. They are responsible for lowering a metal column the size of a blue whale into position in the heart of the works.
Their task is made all the more complicated by the fact that the tower, which weighs 25 tonnes and is shaped like a giant golf club, has to be lowered both downwards and then sideways through a hole in a wall, a hole which was designed with just one purpose, to accommodate the tower for the next few months.
Once the tower is dismantled, the hole will be filled, and the completed canopy above will be the only testament to the fact that the mild steel behemoth ever existed.
Design features such as this can be found all over the site. As well as temporary windows, giant concrete plinths have been constructed across the site just to hold some temporary towers at the correct height.
Some "temporary design features" are, however, rather less temporary than others. To be able to deal with the enormous forces that some of the temporary towers exert on the museum's permanent walls and floors – some deliver loads of 280 tonnes at a single point – much of the museum's structure has had to be permanently reinforced.
Once it is in place, tower 91's metal foundation will sit both inside and outside a gallery. But before that can happen, the installation team need to make sure they have positioned the tower with extreme precision – working to a fine tolerance of just 10 millimetres.
The need for such accuracy can be seen at the top of each tower, where 53 of the gigantic jigsaw pieces that make up the museum's canopy are supported, temporarily, on 256 metal ball-and-socket props shaped like a human hip. As with the towers below them, each of these joints is also temporary, and once the canopy is self-supporting, lowered and finally in place, each of these will also have to be removed.
Given that their foundations have to negotiate skylights, different floors, the interiors of galleries and even flights of stairs, every one of the 118 temporary towers is unique. The largest are as tall as an eight-storey building and, depending on their location, can support as many as six props and six different supersized elements.
If having to coordinate the tower locations with the museum's architecture and canopy is the logistical equivalent of three-dimensional chess. Their installation requires a unique combination of delicacy and brute strength.
To lift tower 91 requires the might of a giant 1,600-tonne crawler crane, the only crane capable of lifting such a load and reaching the 90 metres from Louvre Abu Dhabi's perimeter into the heart of the construction site.
From such a distance, it is impossible for the crane's operator to see what is happening at the base of the tower. Instead he must rely on a "rigger", a specially trained operative identified on site by his green d hat and the walkie-talkie that is clamped permanently to the side of his head. Theirs is a special relationship, as only the crane's rigger can issue instructions to the crane operator from the ground.
At the base of tower 91, the rigger is joined by a white-helmeted supervisor from Wagner Biro, the canopy's engineers. His job is to ensure that the tower is installed with the necessary accuracy, and to liaise with the labourers and their supervisor who are charged with coaxing the 25-tonne structure into position using a combination of oversized spanners, metal levers, and the occasional burst of brute strength.
Far above the din and intensity of the building site's innards, giant platform-like bridges have been built between the towers, whose coarse construction finally gives way to the delicate geometry of the museum's emerging canopy. Up here, among cooling sea breezes, the bridges support a final level of temporary construction, a complex matrix of scaffolding that provides workers with the access they require to apply the finishing touches to the canopy.
"We have a specific period to do everything, to install the dome, the eight layers of cladding, to get the bearings in place ... and start removing all of the towers," Mr Taha explains, considering Louvre Abu Dhabi's stated 2015 opening date.
Before that process can begin, all 85 of the canopy's supersized elements have to be erected, connected together, and then wrapped in the eight-layered aluminium cladding that will help it to project what promises to be the museum's piece de resistance, Jean Nouvel's "rain of light". For Mr Taha, however, there are more immediate and pressing tasks at hand.
"Building all of these platforms is fine, but removing them will be more difficult. You won't have crane access from the top because it will be blocked by all of the cladding. Most of it will have to be brought down manually or we will have to bring in cranes below.
"Right now there is a race to put all the towers in, but there will be a race to get all the towers down."
nleech@thenational.ae
