Architecturally speaking, retractable roofs vary greatly from stadium to stadium in shape, material and movement. For example, Miller Park has a fan style roof, while Toyota Stadium in Japan has an accordion-like roof. Most retractable roofs are made of metal, while some, such as the roof of University of Phoenix Stadium, are made of water-resistant fabric. Interestingly each retractable roof differs in these aspects with the Safeco Field's the only one in North America that does not form a climate-controlled enclosure when in the extended position; rather, it acts as an "umbrella" to cover the playing field and spectator areas during inclement weather, with no side walls enclosing the stadium.
The latest retractable roof design on the Mercedes-Benz Stadium in Atlanta raises the roof yet again with regards to design, construction and operation. It is worth watching the video footage.
A video showing the incredible feat of installing the retractable roof on the Mercedes-Benz Stadium in Atlanta has been released. The footage gives a rare insight into the meticulous planning and sheer scale that is involved in such an undertaking.