It’s 10 degrees above zero in Minnesota, but the fans and players at Super Bowl LII this Sunday won’t have to worry about it: a closed roof overhead at U.S. Bank Stadium will be keeping everyone cozy.
Architectural firm HKS Sports and Entertainment, despite being based in Dallas, knew enough about cold weather to make the roof work in the North. The clear plastic ethylenetetrafluoroethylene(ETFE) top lets light in while keeping the elements out. While a retractable roof that is only opened about four to five times a year can cost $75 million to construct, the $1.13 billion stadium uses a fixed roof. Will the 70,000 fans think it’s worth it?
Designing a $1.13Billion Stadium
U.S. Bank Stadium is built on the same site as the Vikings’ old home, the Metrodome, but stands at twice the size. The inside is made up of wide concourses, high-tech lounges and five of the world’s largest pivoting doors.
To improve getting to the stadium ahead of game time, the site is now better connected to Minneapolis’s transportation infrastructure so that fans and staff can walk for miles to the stadium without going into the open air. One-third of patrons are expected to hike to the stadium via public transit.
HKS also ensured that the stadium itself would be able to survive Minnesota’s harsh winters by creating a sloped roof that prevents snow from building up. While the 60 percent of the roof made of ETFE, with its high R-value and reflective silver pattern coating, will encourage the snow to melt more rapidly, the other 40 percent is a hard deck roof that can sustain the weight of snowfall.
ETFE, most notably used in the Water Cube for the Beijing Olympics, is relatively cost-effective and self-cleaning. 10ft x 300ft panels were made in Germany before being shipped to the site, rolled into place and pumped with air, upon installation.
The material has the added benefit of allowing light in even on cloudy days. It’s also so acoustically reflective that U.S. Bank Stadium is known as one of the loudest stadiums in the NFL. The inside-out effect created by the ETFE is further amplified by the five massive doors located on the stadium’s glazed wall, which is meant to make fans feel outdoors even more.
The inside of the stadium is bigger than it appears from the outside. One-third of the space is built below grade, which allows for the seating of 66,000 fans and up to 4,000 more seats when big shows, like the Super Bowl, roll into town.
The building’s exterior is made up of zinc, though glazing on some portions have animal rights activists concerned that this could endanger birds. For this reason, the Minnesota Sports Facilities Authority will deploy an infrared film made by 3M if animals are hurt by the surface.
Technology also is placed at the heart of the fan experience: 1,300 access points provide stadium-wide Wi-Fi so that patrons can use smartphone apps to navigate to their seats and order concessions.
Uniquely, U.S. Bank Stadium is the first NFL stadium to use LED sports lights, which consume 75 percent less energy than traditional lights and reduced installation loads by 37 percent.
Building a $1.13Billion Stadium
Before construction began, Mortensen, the firm behind Frank Gehry’s Walt Disney Concert Hall, created an elaborate virtual model of the site. More than a fun consumer experience, the models built for the project were meant to ensure that the project would be completed on schedule. In fact, the project was completed six weeks ahead of schedule.
Mortensen used Revit to define the geometry of the structure and Navisworks for more complex areas. Obviously, having a complete 3D model of what the site would look like, including each material and element type for each project team, freed the builders from having to visualize what 2D drawings would look like in the physical world.
Among the tools used for modeling the construction phase of the project was the use of lift drawings, which included the exact dimensions and placement of each of the stadium’s concrete elements. The senior surveyor for the project could then match the model with the actual site to ensure each element was placed in the exact location as determined by the original 3D models.
300 pre-cast concrete panels were used for the snow catch basin, allowing the various trades to coordinate off-site and, thus, in a more controlled environment where quality could be closely maintained and work could be safely performed. Additionally, because they could be poured horizontally within the off-site warehouse, there was greater control over the flow of the concrete. Once built, the panels could more quickly be assembled on-site. In some cases, there were geometries that may not have been possible to pour on-site.
Financing a $1.13Billion Stadium
U.S. Bank Stadium is the first fixed-roof stadium built in the NFL since 2002, the opening of the Detroit Lions’ Ford Field. It has been a long time coming for the Vikings.The owners have been fighting to replace the Metrodome since at least 1999, when former owner Billy Joe “Red” McCombs requested state funds from then-governor Jesse Ventura, who was not at all friendly to the idea.
The new stadium has been funded by a combination of sources, including a combined $498 million from the state of Minnesota and city of Minneapolis and $608 millionfrom the Vikings. While Vikings management has increased ticket prices in order to foot its portion of the bill, the public has contributed to its portion through a combination of appropriation bonds and taxes, which include cigarette and gambling taxes—so far paying for $36 million of the project.
When large projects such as this are taken on by local governments—whether it’s an arena for the Super Bowl or Olympics—the argument provided by officials is that they will boost the local economy. However, sports economists, in most cases, believe the benefits of publicly funded stadiums don’t outweigh the costs.
Sports economist Victor A. Matheson, from the College of the Holy Cross in Worcester, Mass., for instance, has said that Super Bowls in particular generate between $30 million and $130 million in economic activity for the host city. Matheson told The New York Times, “All of the economic stuff, if you’re lucky, is going to wash.”
Matheson, however, does point out that cities do gain an immaterial benefit from hosting these mega-events. “We actually do get measurable impact from people’s satisfaction right after a city has hosted the Olympics, Super Bowl or World Cup,” Matheson said.
As the fans crowd into the U.S. Bank Stadium for Super Bowl LII, it’s possible that not only will they be satisfied, but so will the city around it—at least temporarily.