I was just watching an episode of the Discovery Channel show "Extreme Engineering," devoted to the construction of the Arizona Cardinals' new football stadium in Glendale, Arizona. As I've "discovered" in some web searching, this episode had its original airing long ago, and is now in reruns.
Here's a profile of the host, architect Danny Forster. This news release from Harvard, where Forster is a Master's student, summarizes his experience doing the stadium show:
Forster's first assignment was a new stadium built for the Arizona Cardinals football team. The 63,000-seat stadium features a retractable roof and a natural turf field that rolls out on tracks so the grass can get the full benefit of the Arizona sun between games. When Forster arrived, teams of masons, ironworkers, carpenters, electricians, and other specialists were working furiously to get the stadium ready for the 2006 season. It was up to Forster to enter this monumental hive and persuade the worker bees to explain their jobs on camera.
"There was no preparation. Everything was improvised. Mostly I would just walk up to people and say, 'What are you doing? Can I try it?' Then most of the time I would fail at whatever task it was, which adds comic value and also shows how incredibly skilled these workers are."
...In the show on the Cardinals stadium, which aired in April as a pilot, Forster watches as workers ignite a mini-volcano to fuse the steel rails carrying the moveable field, he gets stuck high above the ground in the gondola of a cherry picker, and he takes a vertiginous stroll across the stadium's thin fabric roof. One of the show's running jokes centers on Forster's fear of heights. When the workers coax him into ascending the stadium's 240-foot roof, Forster gazes out over the desert landscape nervously but with a visible sense of triumph.
And, all this done in 110 degree (F.) temperatures, which not only are uncomfortable for the workers, but also wreak havoc with the finely calibrated construction processes, due to expansion of the materials.
All television shows need to have some drama, so the show focuses on various "crisis" moments in the construction. As mentioned above, Forster gets stuck (along with his camera operator and a veteran iron-worker literally working his last day before retirement) in the cherry-picker. As Forster's further investigation shows, because the weight of the three men in the "bucket" component (555 pounds) exceeded the 500-pound limit, and the long arm was stretched out too far horizontally, there was a danger of everything tipping over; thus, the cherry-picker automatically halted, until the bucket could be lowered and brought in horizontally (this is just my recollection, I may be off a little in the details).
Another storyline is that a heavy piece of equipment has fallen from the roof onto the field, although luckily within a delineated "no walk" zone, so nobody has gotten hurt. This leads Forster to investigate what's being done "up on the roof," and he discovers the workers have been having difficulty lining up the "train tracks" for the retractable roof.
One component of rail is slightly misaligned with the others (by 1/27 inch beyond tolerance -- thinner than a credit card -- or, if I heard correctly, 0.06 degree, in engineering terms). As is pointed out on the show, even if the roof panels are able to glide along the tracks, any flaws can lead the wheels to wear out prematurely.
The people monitoring the project "on the ground" in Arizona then call Uni-Systems, the Minnesota engineering firm overseeing the construction, and get approval to accept this deviation from tolerance.
The Discovery Channel seems to re-air older shows periodically, so you may be able to see this show if you want to. Also, these shows can be purchased on DVD. Whether you see (or have seen) this episode or not, this description should give you some idea of what goes into building this type of stadium, the next time you view a football game from the Cardinals' new stadium or other retractable-roof facilities.
Also worth a look is the summary page for the new stadium at Ballparks.com. When the new page comes up, look in the upper-left corner and click by "Future" and "NFC," then on the Cardinals' stadium.