To keep the 66,000-tonne deck from being heavier, designers specified thin resin road surfacing, says Henrik Polk, Cowi's chief project manager. Since each tonne of deck weight needs 1.8-tonnes of cable steel, every tonne counts.

The cables are so large that each uses 42% of its capacity just to support itself, says Chris Walker, project engineer with Flint and Neill, a Cowi subsidiary. A total of 171,000 tonnes of cables is required, he says.

Because of the cables' 1.27 m diameters, an innovative tower-top saddle design has been developed, says Walker. A conventional single-trough saddle would need to be huge to contain each cable's 349 strands, he explains. The towers will have flat, multigroove saddles that contain groups of strands that exert only vertical forces.