The report is being carried out for UK Sport, the former UK Sports Council, by sports architect Ellerbe Beckett and will be delivered in three weeks.
The current scheme, submitted by Foster and Partners/HOK-Lobb for planning on Monday, provides for 90 000 seats for football matches and 67 000 for athletics events.
HOK-Lobb presented the scheme to Ellerbe Beckett on Tuesday. It proposes two ways to increase the seating capacity to 80 000 for the Olympic Games. Both require the construction of an athletics track on a platform raised 6 m above the football pitch in the event of a successful World Championship or Olympic athletics bid.
The first option, which involves reprofiling seating at the front, would cost £20m and would take six months to build and another three to dismantle. The second, which involves the construction of 10 extra rows of seating at the top of the bowl, would cost £57m, plus any extra planning gain that Brent Council might levy because a larger stadium would require a more robust transport infrastructure.
If Ellerbe Beckett recommends the second option to UK Sport, this may require Foster/HOK-Lobb to submit a new planning application. This would delay planning approval until after the target date of March.
