Vikings' challenge at U.S. Bank Stadium: Replicate Metrodome noise

Three years ago, the Minnesota Vikings abandoned one of the NFL's most established home-field advantages. They moved out of the Metrodome, a compact structure that facilitated acoustic mayhem on game days, and built a cavernous replacement that is nearly twice as large but with the same fan capacity.

So as the Vikings inaugurate U.S. Bank Stadium with a preseason game Sunday against the San Diego Chargers, a major issue lingers: Can it possibly provide the same competitive advantage as the Metrodome? Can it be as loud and disruptive to opponents? And if not, did the Vikings sacrifice some of that benefit for design and revenue-boosting enhancements?

I've been fascinated for years by the impact of raucous CenturyLink Field in Seattle, where the Seahawks are 78-34 and 49-63 elsewhere since 2002, and wondered why other teams in a copycat league have not sought to emulate that advantage on their own terms. In digging into the issue, I've learned it's more complicated than simply replicating Seattle's conditions. Regardless, most of the stadiums opened after 2002 have failed to provide a similar advantage.

Here's what I can tell you about the Vikings' new home: It has a relatively intimate setting relative to its size, boasting seats as close as 41 feet from the sidelines. Its upper deck is cantilevered to bring it closer to the field than it otherwise would be, and its irregular roof is projected to reflect more sound toward the opponents' sideline than it will toward the Vikings'side. The partial transparency of the roof will create shadows on the field during the afternoon, and five doors measuring between 75 and 95 feet tall could add wind and cold air to the mix -- all elements that coach Mike Zimmer has been busy studying this summer.

Ultimately, though, one of U.S. Bank Stadium's chief architects acknowledged the same mitigating factor voiced by the designers of CenturyLink Field and other new stadiums.

"It's really, in the end, all about how much the fans yell and scream," said John Hutchings of HKS, Inc. "If the people from the state of Minnesota come to a Vikings game and scream at the top of their lungs, this stadium will be pretty intimidating. If they sit back and are more passive, then I don't think it is going to come across as intimidating to opponents as it could be."

The true roots of a franchise

Nationally, of course, Minnesota is associated with cold and snow. The Vikings are remembered in their 1970s heyday for playing outdoors at Metropolitan Stadium.

But for three decades, the Metrodome -- where it was 65 degrees every day -- was the statistical crux of the Vikings' success. Take a look at the first chart, which represents the largest disparities between winning percentages at home and on the road. It represents home-field advantage better than home winning percentage because it scales for elite teams that win everywhere they play.

During the Metrodome's existence from the 1982-2013 seasons, the Vikings had the second-highest differential between their home and road winning percentages. (They had a .644 winning percentage at home and .404 on the road.) Only the Kansas City Chiefs, who play at the loud and disruptive Arrowhead Stadium, had a larger gap.

Whether it was real or imagined, genuine or piped in and amplified as opponents sometimes alleged, the Metrodome forced opponents to adjust in unfavorable and often unsuccessful ways. And believe me, that mystique is a top priority for Zimmer and the rest of the Vikings' football operations staff at U.S. Bank Stadium.

"They came to me during the planning," Zimmer said, "and really the only thing that I wanted was noise."

During a conversation this summer, Zimmer revealed one secret -- or perhaps just engaged in some engineer-level gamesmanship with his team's oppoennts -- about the stadium's roof.

"Supposedly," Zimmer said, "it will reverberate more to the visitor's side. That's what I've been told."

Indeed, the home and visitor sides of the roof are covered by different material and are angled for easy snow melt and removal. The one angled toward the visitors' sideline is covered by a transparent substance known as ethylene tetrafluoroethylene (ETFE). The side that angles toward the Vikings' sideline is metal, from which sound-absorbing lapendaries hang.

"That could be advantageous," Hutchings said, "depending on who is doing the yelling."

A burst of sun and air

Zimmer made clear this summer that he wanted his players "focused on blocking and tackling and not worried about the stadium." But like any NFL coach, he has spent plenty of time thinking about it himself.

In addition to the noise factor, Zimmer commissioned a study on the shadows cast by the steel beams that support the ETFE side of the roof. At the time of our talk in late July, Zimmer had 66 time-lapsed photographs of the sun setting through the ETFE on his desktop computer.

"I don't think it's going to be a very big factor," Zimmer said. "It's very light in there, but it doesn't look like there will be a whole bunch of shadows until later in the ball game."

Sunday's game is a noon Central Time kickoff. The preseason finale is Sept. 1 at 7 p.m. CT, giving the team two different environments to study the shadows' impact. They're likely to be at their most notable at the end of early games or the start of 3:15 p.m. CT games.

Meanwhile, Zimmer is intrigued by the doors as an opportunity to let in cold air and maybe a wind current.

The doors face west and are subject to the same rules as retractable roofs in other stadiums; a decision must be made 90 minutes before game time on whether they will be open or closed. Early wind testing revealed no discernible air speed on the top of the goal posts, Zimmer said, but the results could be different with fresh air flowing and 66,655 fans in the building.

Zimmer has considered leaving the doors open during late-season games to make the building less comfortable for opponents, but Hutchings said that option wasn't discussed during the design process and suggested it would have unfavorable consequences. An experiment seems unlikely but possible.

"We never intended on a December day to let the frigid weather into the stadium," he said. "I'm not sure it would be a great fan experience, especially for those on the lower bowl near the doors. It would get pretty cold there, but stay warmer on the other side. We never had that discussion -- to create that kind of environment. I suppose it could be done, but I don't think, based on all of the heat and air conditioning that has been placed in that building, that they would consider it."

Time to find out

The stadium has hosted one sporting event and two major concerts this summer. Team officials sat in the stands in July for a Premier League soccer match between AC Milan and Chelsea, which drew 64,101 fans, and recorded a high of 106 decibels -- not too far off from the 112-116 decibels they typically recorded on the Metrodome field for Vikings games. The current world record for stadium noise, according to Guinness, is 142.2 decibels at Arrowhead in 2014.

"It wasn't a real scientific study," said Bryan Harper, the Vikings' vice president of content and production. "But we were there, so we measured it, and it was a positive indication that this building is going to be loud. It's much bigger than the old one, that's true, so you just don't know for sure until you get in there and play a game."

The second chart illustrates recent trends among home-field advantage at NFL stadiums. You'll notice only one that opened after 2002 in the top 12: MetLife Stadium for the New York Jets. (It hasn't worked quite as well for the New York Giants lately.)

Most notable to me is that the Dallas Cowboys, who play in another HKS-designed stadium, have the NFL's worst ratio between home and road winning percentages over the past three years. AT&T Stadium is among the league's most celebrated marvels of design and technology, but it often feels like a neutral site for the Cowboys. The team has won at a better percentage on the road during this time period.

One theory is that high ticket prices combined with personal seat licenses in new stadiums have pushed out rabid fans and shifted the demographic into a more corporate environment. The Cowboys, for instance, had by far the highest Fan Cost Index -- as determined by Team Marketing Report -- of any team in the NFL. In 2015, the average family of four spent $634.80 for a typical trip to a Cowboys game including tickets, parking, food and souvenirs, according to the analysis.

The theory diminishes the impact of design and size and focuses on the makeup and desire of the crowd itself. If that's true, the Vikings feel confident they can maintain the advantage they've carried for decades.

"Our fans are educated," Harper said, "and that's half the battle right there. I'm very confident that the building was designed in a way that is going to make us really proud to have that home-field advantage and have crowd support and have the effect of noise on a game. It's going to be great to see. It's still an unknown until we get in there, but we're certainly looking forward to it."