Designed by Iraqi-born architect Zaha Hadid, the centre will mark the gateway to the Olympic Park in Stratford.

 

Originally estimated to cost £73 million, it is now estimated to come in at nearly four times that amount, despite the stingray-shaped roof being scaled down and redesigned amid cost fears.

 

Sebastian Coe, the chairman of London 2012, said: "The design of the roof is iconic and will be one of the lasting images of the London 2012 Games."

 

The 17,500 seat centre will host swimming, diving and water polo during the Games, but will be reduced to 2,500 seats afterwards.

 

David Higgins, the chief executive of the Olympic Delivery Authority (ODA), said: "The Aquatics Centre is on track to be a fantastic gateway to the Games.

 

"The lift of the sweeping wave-shaped roof is one of the toughest construction and engineering challenges on the Olympic Park and will showcase the world class expertise involved in delivering the venues and infrastructure for London 2012."

 

Builder Balfour Beatty was the only company left in the bidding for construction after France's Eiffel and Germany's Hochtief withdrew.

 

Hadid said: “It is very exciting to see such progress on site.

 

"This is a key milestone in the construction programme we have been looking forward to since winning the 2004 competition.

 

"The roof of the Aquatics Centre reflects the fluidity of water and will provide an inspirational legacy for all Londoners well beyond the 2012 Games.”

 

When complete the 160m long column-free and up to 90m wide roof will rest on two concrete supports at the northern end and a 28m long and 5m wide, supporting ‘wall’ at its southern end.

 

 

 

A huge 30m steel truss weighing over 70 tonnes has been lifted into place on top of the southern wall.

 

This has already been connected with the first sections of 15 steel trusses which will span up to 120m to the two northern roof supports.

 

Over the coming months steel trusses fabricated in Newport from plate rolled in Gateshead, Motherwell and Scunthorpe , will be assembled on the Aquatics Centre site and connected together 20m off the ground on three rows of temporary support trestles.

 

Once the huge steel roof frame is complete it will be lifted up to two metres at its southern end, turning on complex rotating joints in the northern roof supports.

 

The temporary trestles will be removed and the 160m long roof frame lowered on to its three permanent roof supports, which have been built with over 20,000 tonnes of concrete.

 

As the full weight of the roof rests on its supports it will slide approximately 20cm into its joints at the southern wall.

 

The roof has been designed, through wind tunnel testing and computer modelling, to stretch, twist and contract in response to the effects of snow, wind and changing temperatures.

 

Once the steel roof is in place this summer work will begin on the aluminium roof covering. Installation will then start next year on the timber cladding of the ceiling which will sweep outside to cover the northern roof supports.

 

The foundations of the permanent venue are complete and work will begin on the pool structure once the steel roof is complete.

 

The area, on a former industrial site, was severely polluted with oil, tar, solvents and heavy metals such as arsenic and lead in the soil, which had to be cleared and decontaminated.

 

Four skeletons from a prehistoric settlement were also removed. 

Related Stories:

February 2009:	Welsh steel to support London 2012 Aquatics Centre
December 2008:	Olympic Aquatics Centre construction on schedule
September 2008:	Work progressing quickly on Aquatics Centre
July 2008:	Construction starts on controversial Aquatics Centre
July 2008:	London 2012 play down fears over Aquatics Centre