Olympic authority unveils its designs for 2012 stadium

The most eagerly awaited design for a construction project in recent British history was unveiled on Wednesday by the Olympic Delivery Authority.

By chance, the announcement coincided with another keenly anticipated Olympic event: the submission of Balfour Beatty’s tender for the aquatic centre. That bid weighed in at £200m.

During the Games the £496m stadium will have an upper tier of seats and a cable-stayed roof covering two-thirds of the 80,000-strong audience. It will be surrounded by a fabric “wrap” illustrated with designs and topped off with a steel crown.

After the Games the stadium’s upper tier and roof will be dismantled, with the lower tier remaining as a 25,000-seat stadium for legacy use. Steel and materials used for the temporary structure will be recycled.

The design-and-build team for the stadium is made up of Sir Robert McAlpine, architect HOK Sport and structural engineer Buro Happold.

But Alison Nimmo, the ODA design director, said an iconic design such as Norman Foster's arch at Wembley Stadium would not have fitted with the ethos of the stadium. She said: “Do you invest in so-called big names in architecture, or do you ensure legacy by taking a more fundamental approach?”

Meanwhile, Balfour Beatty, now the sole bidder for the aquatics centre, has given its tender to the ODA. Sources close to the aquatics centre bid said that, together with construction of a neighbouring bridge and plaza, the building of the centre will cost about £200m.

This is far higher than the bid book estimate of £100m, but that does not take in the construction of the surrounding infrastructure. A timber roof is being considered for the structure although it is understood that it resilience is the subject of ”security concerns”.

It is understood that the centre, like the stadium, will become a design-and-build project after the guaranteed maximum price is agreed. Construction is expected to start in July.

The latest project cost estimate for the stadium is £496m, but neither Rod Sheard, HOK Sport’s senior principal architect, nor John Armitt, the ODA chairman, was able to name a build cost at the design launch.