The joint venture had 10 derrick cranes on the decks and used a mobile crane for both fronts on Tsing Yi, says chief engineer Ayala. We had the capacity to accelerate due to the fact that we have an erection system that had never been asked previously to go the limit. At Ting Kau, we were on the limit. By coincidence, Freyssinet finished work at the Tagus River cable-stayed bridge in Lisbon last winter. Working on four cables simultaneously at each of six cantilever ends, Freyssinet first erected each stay's high-density polyethylene sleeve around a single strand.
Strands comprise galvanized steel wires, which are protected by wax and hdpe coating.
The contractor then added more strands, up to 55 per cable, stressing them individually with its computer-controlled Isotention system from the pylon top. According to Freyssinet, it typically erected 28 cables a week, including 12 at the main tower. The third factor contributing to the schedule delay was foundation construction. The central tower required construction of an island in mid-channel, formed by placing 502,000 cu m of rock and sand. Work at the Tsing Yi tower foundation proved more difficult.