TEMPORARY SEATING in London's Olympic stadium was this week singled out as the key reason why the venue's revised budget is set to be double that of original estimates.
Engineers identified the complexity of building a landmark stadium with a permanent structure capable of holding 25,000 seats plus an additional 65,000 during the Games.
In London's original bid to stage the 2012 Olympics, the main stadium was priced at £232M.
But industry figures have been quoted as placing the stadium's true cost at anywhere between £350M and £630M.
Detailed designs and a revised budget were due to be released in February.
Taking the average of £490M, the 2012 stadium is on a par in terms of cost per seat with Arsenal's Emirates stadium (see box). This was also built by the Olympic stadium team of Sir Robert McAlpine, Buro Happold and architect HOK Sport.
However, removing the temporary element sees the cost per seat rocket to £19,600, more than twice the cost per seat of Wembley.
Stadium guru Stephen Morley has previously warned that reducing the stadium from 80,000 to 25,000 seats was unsustainable, because it would be left with disproportionately high running costs (NCE 6 October 2005).
'Where are these extra costs coming from?' asked one engineer close to the Olympic Delivery Authority.
'You have to say it's the temporary element, as stadiums with a similar capacity to the permanent structure tend to range between £30M and £50M.' Whitbybird design director Mark Whitby said the proposed Olympic stadium was unlike anything gone before, so it was dif ult to apply existing cost criteria to it.
The ODA would not comment directly on the costs. A spokesman said: 'Meeting the requirements of Games and Legacy and reducing the seating from 80,000 to 25,000 makes the stadium a unique design and engineering challenge.
'We have stated that we will not continually comment on speculation about the stadium cost while we are still in commercially sensitive negotiations with Team Sir Robert McAlpine.
These discussions are progressing well and we will be announcing more detail soon.' The overall Olympic budget has been con med at £9.3bn, four times the bid cost. Revised budgets for specic projects have yet to be revealed.
The cost concerns emerged in the same week that the basketball and fencing arenas became the t temporary Olympic venues to go out to tender.