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The modern stadium looks a little bit like a matchbox. Push on one end and out slides a tray. But rather than matches, the tray contains soil, drainage, water pipes and grass; in other words a completely irrigated sports field. It weighs a little more than the matches and their flimsy wood and paper container however, being a solid concrete trough more than 1m deep and usually, as the cliched comparison goes, the size of a football pitch.
That at any rate is how the Dutch constructor Hollandsche Beton Groep, envisages the 21st century stadium. And HBG is well into realising the second and largest version of the vision for Shalke Football Club at Gelsenkirchen in the middle of Germany's former industrial heartland, the Rurhgebiet. A first - as it were prototype - model at Arnheim in the Netherlands has been operating for two years.
The company has three other projects under way. One is design and management of a smaller football stadium in Rostok in former east Germany. And HGB is advising on two others, one at Coventry in the UK, now in the design stage and another in the Irish capital Dublin, according to Frits Bakker, one of the engineers responsible for special concept developments at the firm's Dutch headquarters.
There could be many more to come. The stadium market is booming in Europe. Football teams increasingly want all-seater stadiums, especially as standards for international facilities become more stringent. If as expected, the 2006 Soccer World Cup championship comes to Europe, many new stadiums will be needed, especially if the venue is Germany which has not rebuilt since the mid-1980s.
Single sport stadiums, owned by football teams or tennis centres now want a new kind of multi-functional arrangement, sometimes called the third generation. Then rock concerts, exhibitions, boxing matches, and so forth can be staged to supplement the takings from the weekly football.
'They have greater openness and more facilities on the stands, ' says Bakker. Part of the concept is the walk-around concourse lined with shops and food outlets. Usually too, there is a ring of private and corporate boxes.
To stage such varied programmes, a stadium needs to be fully enclosed to make it more controllable for the increasingly important demands of television. But which different types of staging or surfaces can be placed.
Bakker thinks the concrete trough is the better answer because the pitch sits completely outside the stadium for most of the week. The grass is therefore exposed to a normal weather regime. The move into the stadium takes six hours.
There were teething troubles at Arnheim but HGB has now perfected the system, he adds. The concrete trough containing the playing surface is supported on a number of short concrete legs - about 380 at the Arnheim stadium.
Each leg is tipped with a teflon pad which slides along steel bands set into the concrete base of the stadium. The pads are changed after about 50 slides. Wheels were considered but pads are cheaper.
The key item in the process is a special push unit patented by the firm. It looks like a small locomotive and has grippers which clamp on to rails running in troughs between the steel slide bands.
Hydraulic jacks then push the pitch forward for about 1m before the clamps are released, the jacks retracted and the locomotive pulled up before it clamps on again for another push.
At Arnheim it was discovered that inertial effects meant greater power was needed to start the process and the locos have had to be beefed up. The firm says operations have gone perfectly for the last eight months. At Gelsenkirchen (see box) units will have 450t push power and three out of four will suffice to move the pitch.