ENGINEERS WERE still investigating how a 50t steel rafter on Wembley Stadium's northern roof canopy dropped 500mm at one end last Monday, as NCE went to press.
The 30m long rafter, labelled R24, should have been temporarily connected to a steel girder or leading edge beam. This skirts the edge of the northern roof which overhangs the football pitch.
Welders were preparing to permanently weld the rafter to the leading edge beam at the time of the collapse.
Temporary steelwork arrested the rafter's fall and prevented it from hitting workers below.
The rafter is part of the northern roof canopy which also supports part of the stadium's moveable roof.
Work around the rafter stopped as soon as the collapse occurred at 8.35 in the morning.
All 3,500 workers on the site were evacuated in accordance with main contractor Multiplex's standard procedure following incidents.
The Health & Safety Executive was notifi ed of the incident but decided not to attend.
Workers returned to site on Tuesday but the area around R24 was cordoned off.
Multiplex managing director Martin Tidd said that the connection failure was not due to a design fault and that steelwork contractor Hollandia and designer Connell Mott Macdonald were working on a 'safe methodology' for the erection of the rafter.
The rafter has now been secured in position but will have to be jacked back to the correct height before being permanently welded. The stadium is two months behind programme.
A revised completion date has not yet been set.