Vikings stadium: Doors, shadows and more

You came at me from all sides Tuesday with questions on the Minnesota Vikings' stadium design. I had a few answers but jotted down most of your thoughts for further pursuit. Let's use this post as a jumping-off point for what I consider the most relevant and pressing issues.

  • Pivot doors: The design calls for five glass pivot doors on the west side of the stadium, and many of you want to know how they will work. Here's what I can tell you: Each of the five doors is 95 feet tall on a stadium that is 205-270 feet tall at various points. There will also be louvers on the east side of the stadium to help air circulation, but from what I understand, the west side of the stadium isn't really a window in the way we discussed before the unveiling. The area above the doors is transparent but fixed. Regardless, fresh air can still enter the building. The team has wind tests scheduled to help establish a protocol for leaving the doors open.

  • Shadows: The Vikings bill the stadium as having the largest transparent roof in the world, so many of you are asking about shadows that would presumably be cast down to the playing field from the support structure. In a news conference Monday night, stadium designer Bryan Trubey of HKS said there should be "no shadow line from hard structure" and that the stadium will be "a completely open and totally illuminated building." According to Trubey, the roof structure is relatively light, allowing for smaller and less frequent structural pieces to support it. From the team's release: The stadium will have the "lightest and most efficient roof structure in the nation for a major new stadium, which will include a single large steel super truss providing primary support for the main long span roof."

  • Noise: How will the clear ethylene tetrafluoroethylene (ETFE) roof perform acoustically? Will it amplify crowd noise? Absorb it? And how will it impact the public address system, a big complaint of fans in the Metrodome? According to Trubey, the roof surface is "a moderate kind of acoustic material" and is "not very reflective." It's possible we won't know the crowd noise answer until the stadium opens.