MICHELANGELO, the Italian Renaissance artist and sculptor Michelangelo wrote:'a bridge ought to be constructed as though it were intended to be a cathedral, with the same care and the same materials.'That was nearly 500 years ago. The Tsing Ma bridge, five years in the building, will last 120, even taking account of our aggressive climate. The materials are not elegant marble, solid granite or sturdy oak, but the man would have approved of the care and precision that has gone into what will soon become South China's greatest landmark.
It will be the first and last marvel every passenger arriving and departing from Chek Lap Kok will experience: the gateway to Hong Kong. A slender apparition in the far western harbour that is designed and destined to be the oxygen bypass for the city's hardening arteries, Kai Tak and the KCR.
As a cathedral is grand, so this bridge will be an impressive monument. There is an eerie sound way up there, on the towers 206 metres above the waves of the Ma Wan channel. It's a whispering metallic twang, the resonance of the strings of a giant sitar. It is not dissimilar to the sound of vibrating rails presaging the approach, some kilometres away, of a train. That's the sound of good news,'says an engineer. Work is going according to plan: one of a pair of self-propelled Dayglo-red spinning wheels is transporting, marginally faster than the Shau Kei Wan tram, four pencil-thin wires across the great divide between Tsing Yi and Lantau. Before they are finished, the master builders, the Anglo Japanese Construction Joint Venture and their 1,100 workers - ex-Gurkhas from Nepal, men from Malaysia, China, the Philippines and Hong Kong - will have seen to the transporting of enough wire to stretch around the Earth four and a half times.
A suspension bridge is like a washing line, a cord with a sag. It's a matter of working out how thick the line has to be, and how strong the supports, to hold up how much washing. In this case, it's a lot.
The spinning wheel rolls a loop of eight wires at a time. When it has done this 45 times and made 360 individual wires - these are ready to form one strand. The cable needs 91 strands. It will then be just over a metre thick. There are two of them, they weigh 28,000 tonnes and from them will be suspended the deck which will carry cars, trucks and trains to and from the world's most disputed airport. No bridge in the world will carry such a load for such a distance. The whole show will withstand winds of 300 km/h.
Making the cable is called spinning, a misleading term. The cable is not twisted as in a tread, or a rope. Each wire within each strand runs parallel to its neighbour for the entire length, from anchorage in the bedrock on one side, over the pillars to its anchorage on the other side, two kilometres away. The tension of the whole cable is determined by the adjusted tension of the very first of the 33,400 pencil thin wires. Between them they form a 'cantenary', the natural shape of a washing line, without any clothes. It's a word that doesn't feature in many dictionaries but it can also be applied to the the curve of a gold chain hanging naturally from a woman's neck.
