'Mantis' pops up at Eden Park

These structures have been nicknamed the Praying Mantis. Photo / Greg Bowker

Fletcher Construction was yesterday erecting the second roof beam on Eden Park's new south stand.

Site manager Brent Fleming said 16 roof beams would rise on the new stand in the next few weeks.

The stand is being built for Rugby World Cup 2011 and will be finished next year.

Each roof beam has a span of 33m and is assembled in a number of sections.

The first structure to be hoisted to level eight of the stand via tower crane is the structural support section, which is bolted to box girders. This forms the base of the beam.

These structures with enormous pole legs have been nicknamed by workers the Praying Mantis.

The second part of the roof beam is the 33m-long arm which spans from the back of the stand to the front.

Each of these arms is being bolted to that first cantilevered section.

Fleming said the 16 beams were some of the largest and heaviest put up in New Zealand.

They are being built by Grayson Engineering in Manukau and Eastbridge Engineering in Napier and are being trucked to Eden Park.

Grayson, established in 1972, employs about 90 people and says it has one of the best equipped structural fabrication, plate cutting and mechanical fabrication workshops in New Zealand.

Eastbridge is privately owned and specialises in the supply of steel bridging, towers and poles and heavy steel fabrication.

Rainer Hagspihl, manager of structural steel and precast for Fletcher Construction, based at Eden Park, said each beam weighed 27 tonnes.

"The rear sections are 12.2m long and weight 12 tonnes. The cantilever section is 25m long and weighs 18 tonnes and the tips are 5m long and weigh 2.5 tonnes," he said.

The beam-building job was split between the two engineering firms for expediency. "In order to meet our site programme, they had to split it up."

The builder and more than 40 subcontractors are working from prefabricated buildings around the site's perimeter.