Q10. Is it true that the grass soccer pitch at the Sapporo Dome moves by floating on air?

A10. Yes, it's true! It is called the "hovering soccer stage" and is the first such system anywhere in the world.

Sapporo Dome has two arenas, one indoors and one outdoors. When the indoor arena is being used for baseball, the natural grass soccer pitch is left outside, allowing the grass to grow well. When the dome is used for soccer, this pitch is moved inside using a hovercraft-like mechanism.

Here is a more detailed explanation: First, the seating behind center field in the indoor baseball arena automatically retracts 90 meters (99 yards), opening up a gap. The "hovering soccer stage," floating 7.5 centimeters (3 inches) above the ground on air pressure, is wheeled through this gap and into the dome at a speed of four meters per minute. The baseball pitcher's mound automatically withdraws into the ground.

The soccer stage measures 120 by 85 meters (132 by 93 yards) and weighs 8,300 tons, but when it is floated it weighs only one tenth of this, light enough to be able to move it on wheels. The bank of seats for watching soccer then moves automatically into the gap left by the baseball seats. It takes about five to seven hours to complete the changeover from baseball stadium to soccer stadium. What happens to the artificial turf used for baseball? It is rolled up and put away in storage.

There are a number of guided tours of Sapporo Dome, but unfortunately none of them include watching the soccer stage being moved. It cost 42.2 billion yen (325 million dollars at 130 yen to the dollar) to build the dome.