On January 30, athletes train at the Ice Ribbon, China’s National Speed Skating Oval, in preparation for the Beijing 2022 Winter Olympics.

The saddle-shaped roof of Ice Ribbon adopts a single-layer cable network structure, which is the largest such roofing of a stadium in the world, with a long span of 198 meters and a short span of 124 meters. The ice layer is surface by direct cooling with carbon dioxide, which can keep the temperature variation across the ice surface within 0.5 degrees Celsius. In addition, there is a 4K high-speed camera for live TV broadcast.