The western tower, along with the first three deck segments, were built at the same time and completed in mid 1993. During construction the three deck segments were supported by scaffolding and then, when tower construction was completed, the first stay cables were installed.
Single strand showing the seven galvanised steel wires
The stay cables were constructed from multiple wire strands surrounded by a black polyethylene sheath supplied by Vinidex Pty Ltd.
The individual strands, 15.7mm in diameter, consist of seven galvanised steel wires waxed and covered in polyethylene.
The number of strands in each sheath varied - increasing in number from 25 to 74 towards the centre of the bridge.
Wire strands within cables.
Polyethylene sheath ready for joining.
12m lengths of polyethylene sheath were welded together on the deck and an initial wire strand drawn in. The sheath and strand were then winched into place and the initial strand fixed into the anchor points and tensioned to its predetermined load. 3.
Cable strands within the polyethylene sheath and the drawing wheel.
Joined length of polyethylene sheath ready for placement.
The remaining strands were then individually drawn into place through the polyethylene sheath from the deck level using a drawing wheel.
After being secured in an adjustable anchorage point in the tower head, the strand was cut to length and fixed at deck level.
A hydraulic jack at the tower top was then used to set the final strand tension to match that of the initial strand. 1.3.8.
The cable drawing wheel.
Tower anchor points.
Cable stay anchor points - eastern end.
Anchor points under the deck - western end.
Stay cables are numbered viewed from the spiral ramp eastern end
Initially the stay cables were subject to serious vibrations. Experimentation using heavy ropes tying the stay cables diagonally back to the deck reduced the problem.
A permanent solution replaced the ropes with thin spring loaded stabilising cables between the stay cables and the deck.
The spring failure safety link shown below was added later.