'This is Madonna. Her show is perfect. There can be no mistakes'

Cue lights, music, mechanical bull: the preparations for this week's Madonna tour

In the maze of corridors that runs beneath the Palais des Omnisports, a security man is talking into his mike. "Can we get the VIPs into their seats, please? Ten minutes till the show." There's a trace of anxiety in his voice that is out of keeping with the air of calm in which everyone else is going about their business.

Through an open door you can see band members relaxing on black leather sofas. In the canteen, the choreographer is chatting away over a plate of chicken and rice. The production manager, wires protruding from his black combat gear, ambles out of his office, collecting a chewy sweet from a plastic tub by the door. The PR lady, in her pale trousers and vividly coloured top, is a picture of serenity. She's seen it all before.

The atmosphere above is different. Even with the lights still up, it's one of frenzied anticipation as 16,000 people take their places in this vast indoor arena in the Bercy district of Paris, and await the arrival of the world's greatest pop superstar. It's Madonna's Drowned World tour – her first for eight years, and her most ambitious and daring ever. And this week, after nearly a month in mainland Europe, it arrives at Earls Court in London before moving on to the States.

As a solo artist, Madonna is without equal, and her desire to put on a spectacle, not just a concert, creates challenges that have extended the boundaries of what a rock'n'pop tour can achieve.

That's what Mark Spring says, anyway. Spring is the guy in the combat gear, the production manager of the Drowned World tour, and someone whose responsibilities for making things happen, night after night, seem so immense and so frightening that you wonder how he ends up not being drowned himself.

"This is the most complicated thing I've ever done," says Spring, who, at 43, has a track record that takes in such diverse acts as Seal, Garbage, Metallica and Ricky Martin. "And the Madonna mystique figures very highly, so you have a whole other level of professionalism you have to attain. It's not that you wouldn't do your best, of course. But this is Madonna. Her show is perfect. There are no mistakes."

Which is some claim, considering just how much there is that could go wrong. The tour has more than 100 tons of equipment. There's a stage the size of three tennis courts, and as well as Madonna and a troupe of 10 dancers and two backing vocalists, just about everything inanimate on it moves too. Above the stage there's a vast "grid", comprising truss sections, chain motors, cabling, and other control devices that link, electronically or mechanically, with what's happening below. There's lighting and sound, including four huge video screens that form the backdrop to the stage. There's a mechanical bull that Madonna rides. There's the equipment needed to create flying sequences that involve aerial combat in the style of the film Crouching Tiger, Hidden Dragon. And when a run of shows ends it all has to be packed up, taken to the next venue, and reassembled in identical fashion.

No two venues are alike, of course, and after Bercy, Earls Court offers its own set of problems. "It's old and it's tall," Spring explains. "I have to build an extra grid so that everything is in the right place." Spring isn't the only one worried – not that he seems the sort of person who would ever show it. Drowned World's director and choreographer is Jamie King, a charismatic 29-year-old from LA who is to the visuals side of Madonna what arrangers and composers William Orbit and Mirwais are to her music. He remembers Earls Court from a show he did with Ricky Martin. "The spotlights are so far away. That means they're going to be huge when they get to the stage. But we've got a great lighting team."

Tours like this one – "a machine on the move" is Spring's description – create a whole economy of their own. It started as soon as Madonna decided that she would hit the road again properly for the first time since her Girlie Show of 1993. Two production co-ordinators were commissioned, along with King and Spring. The sets were built in sections by three companies. A permanent crew of around 100 was hired. This is everybody from lighting, sound and carpenters to dancers, wardrobe and make-up. Rehearsals in Los Angeles went on through April and May. Two Jumbo jets brought all the gear over to Europe, at which point production numbers doubled, with the use of locals to supplement those already in place, mainly in set-shifting roles. "When we come through town, everybody benefits," says Spring.

And there is seemingly no end to the jobs that need doing. Without giving too much away, the climax to the Drowned World show requires some vacuum-cleaning of the stage. And as the Palais des Omnisports emptied last week, there was the crew member tasked with the job, busy at it.

By then the VIPs had left. Security could remove their headsets and take a break. Until the next night, anyway.