22nd March 2021
Mike Ashmore (temporary construction works designer) and Buff Malaitai (crane driver) talked about their experience on the Sky Tower tower construction period stretching from 1994 to 1997.
It was after massive foundation piles were drilled 20m down to bedrock and a huge foundation slab was formed the real tower work began. Mike explained how he designed a form and working space that climbed up the tower (a jump form). This was assembled on the base slab which gave shape to the tower as it moved up in sections of 4m until the observation and restaurant deck levels were reached. The form was self-contained with toilet facilities, smoko space etc
The tower crane in the centre of the tower (‘driven’ by Buff ) also jacked itself up with each lift and was stabilised within the concrete structure.
Once the deck levels were reached, the precast concrete ‘fins’ were bolted through the tower wall. This meant the riggers had to work outside the tower, away from the safety of the jump form – but with safety lanyards.
Substantial working platforms to construct the viewing decks were hoisted separately to the jump form and were at limit of crane capacity while they gave access to the framework for the concrete deck units
After building the viewing & restaurant decks the next challenge was erecting the mast above the decks area. It was thought a helicopter could do this but was not feasible. The crane (and Buff’s driving cab) climbed up as the mast sections were inserted.
Dismantling of the crane was hotly debated but ingenious thinking came up with a solution that used a small ‘Chicago boom’ crane to lower the tower crane components down to ground level. The Chicago boom was broken down into pieces that were taken down in the tower lifts
Highlights from Buff the crane driver included:
-a lightning strike on the crane jib that transmitted down the hoist rope to a rigger on the ground who was attaching a load and holding onto the wire rope
– the view was always wonderful
– high winds made the working day a bit shaky
– a butterfly landing on the crane driver’s cab.