American footballers doing their thing

Dual-use at Spurs’ stadium gives NFL a London base

Image credit: Guardian/Eyevine

We look at the technology that helped transform Tottenham Hotspur’s football stadium in London into a state-of-the art NFL venue.

Five days after Tottenham Hotspur (aka Spurs) lost 7-2 at home to Bayern Munich in the Champions League, the Chicago Bears and Oakland Raiders came to the new Spurs stadium to play an NFL (American football) match. The following Sunday, so did the Carolina Panthers and the Tampa Bay Buccaneers.

Spurs were (losing) away at Brighton when the Bears and Raiders played; the subsequent international break meant there were no Premier League matches the following week.

The Spurs stadium, which opened last April, had been designed to take advantage of times when there’s no football of the round-ball kind. Around 60,000 NFL fans turned up for each game. The NFL were able to take their game and their brand to a whole host of new fans and sponsors. And Spurs made millions, not just from the lease arrangement, but also from food and drink sales – £1m apparently, from beer sales alone.

It was, as money men and life coaches say, ‘a win-win’. And by the time bottom-of-the-table Watford arrived on Saturday 19 October to draw with Tottenham, the stadium was back to normal. No sign of any NFL paraphernalia, nothing to upset the football diehards.

NFL has been played in the UK before, at Twickenham rugby stadium and Wembley. In fact, there were two more NFL matches at Wembley in October and early November. However, when NFL comes to Wembley, the teams play on a pitch and in a stadium designed for football. Or rugby, at Twickenham. The Spurs stadium is the first football stadium to be transformed into the sort of venue that NFL teams would come across in their own backyard.

“Advances in technology and engineering enable us to physically transform the stadium back and forth,” says Christopher Lee, the stadium’s project director, from Populous.

Designing such a stadium was far from straightforward, though. Football and NFL might look like similar games, in that players run about with a ball on a green pitch. However, the two sports organise their events very differently.

For a start, NFL pitches tend to be narrower than football pitches, with different markings and lots of colour. And, whereas football managers, their staff and substitutes sit in pitchside dugouts, NFL teams have huge entourages, including lots of very tall players, who tend to stand in their allocated areas.

Playing in a stadium designed only for football, NFL fans can’t sit in the front tier of seats, as they would be unable to see the action. “The stadium owners lose revenue as they can’t sell all their seats and the ground loses atmosphere with the front row a long way back,” says structural engineer Rob Amphlett of BuroHappold Engineering, who came up with the concept for the Spurs retractable pitch.

Amphlett adds that the NFL also likes to put a lot of colour into its pitches. “When they can’t paint the grass because it will be used for football a few days later, it detracts from their branding,” he says. “NFL can superimpose its markings on to the screens for TV viewers, but those fans at the ground don’t get the whole live NFL experience.”

To deal with all this, the Spurs stadium has two pitches: a retractable grass football pitch and a synthetic NFL pitch underneath. In the USA, many NFL pitches are synthetic.

Naturally, the stadium is in the football mode most of the time. But for NFL matches, the operators slide the grass pitch into a storage area called the cave, underneath the south stand, where it can stay for up to ten days in its own artificial environment. Here, pink LED grow lights, an irrigation and cooling system and robot mowers maintain it in good condition. The pitch’s mechanical vacuum systems used for drainage are disconnected for the move and reconnected once in the cave.

First, the grass football pitch is divided into three pitch-long steel sections, each weighing over 3,000 tonnes. These are able to slide between the columns in the south stand – columns built to support the weight of the 17,500 fans that the stand holds.

Amphlett explains that operators run a knife along the joints, providing a half-metre gap between the three sections. Each section has 68 electric motors and 168 wheels, computer coordinated, and the sections slide out, sideways, on two steel sub-frames. The top frame slides over the lower frame, which has three rails with steel wheels at regular centres. There’s an embedded guide rail that stops the pitch skidding off to the side as it moves. These rails are covered with Astroturf before the NFL game begins.

All this takes around 25 minutes. But there’s a lot more to do to get the stadium into NFL mode. The NFL pitch is 1.6 metres lower than the football pitch, which means that when the stadium is in NFL mode, fans can sit in the first row of seats and see over the heads of the tallest players pitchside.

There are other stadiums with sliding pitches. When Amphlett was researching the Spurs concept he looked at FC Schalke’s stadium in Gelsenkirchen which, with its retractable roof, transforms into an indoor stadium for ice hockey, boxing and live music, and at Lille FC’s Stadt Pierre-Mauroy, where the football pitch splits in half with an arena for tennis and basketball underneath. “We decided that for our purposes, it would take too long to move the pitch [in this way] and cost too much,” Amphlett says. There is an aspiration at Spurs to have a football match and an NFL game on the same day.

Spurs' new London stadium

Image credit: THFC

Holding more than one sport in a stadium is becoming the norm in many parts of the world, as owners try to maximise the amount of time their asset is actually being used. In Australia, for instance, any combination of AFL (Australian Rules Football), soccer (our football), the two rugby codes, cricket and athletics may take place in any one stadium.

For designers and engineers, this basically means making the spaces inside the stadium big enough to accommodate the well-attended sport in such a way that it makes the venue appear full for events where the capacity is lower.

That could mean wider public concourses, refreshment kiosks with individual supply lines for beer and other beverages not connected to one main supply line, seats that can be removed or hidden for a sport which pulls a smaller crowd and put back for the more popular code. Also, stands could be built that enable more seats or other infrastructure to be added in the future, either temporary or permanent.

Some stadiums, like the Gold Coast, are built with potential future events in mind. Metricon is an AFL stadium, completed in 2011, which was built with the potential to accommodate athletics, should the area succeed in its bid for the 2018 Commonwealth Games, which it subsequently did. “Removable seats at the northern end of the stadium enabled an international-sized athletics track to be installed and quickly returned to AFL mode in a few weeks, after the closing ceremony,” says engineer Ian Ainsworth, Brisbane buildings leader at Arup, who worked on the stadium.

In some places, stadiums are purpose-built to accommodate non-sporting events. The Singapore National Stadium, opened in 2014, was designed as much for live music events and Singapore’s National Day celebrations as it was to hold T20 cricket matches, football and rugby tournaments and the opening ceremony for the 2015 South East Asia Games.

Amphlett thinks that cultural differences between the UK and Australia make multi-sport stadiums of this sort work better Down Under than in the UK. “Australia is highly regionalised, with big cities and not much in between,” he says. “In the UK, sports clubs are dotted around and like to have their own assets. If you share, the venue is run by a stadium operator and the clubs lease it, which is less lucrative for a club than having its own stadium.”

Pete Ackerley, chief executive of the British American Football Association, would like to see a different sort of multi-use at lower league football stadiums in the UK. Ackerley, who previously led junior development for both the England and Wales Cricket Board and the Football Association, thinks smaller clubs should replace their grass pitches with synthetic ones (something the Conference National League currently allows, but not the Football League) and hire them out to the local community. “It would make good business sense for smaller clubs and they’d make enough money to replace the pitch every few years,” Ackerley says.

The Tottenham stadium, with its two bespoke modes, is a slightly different sort of multi-sport stadium from anything that has been built before. “Historically, when stadiums are shared between two sports, each has to compromise in some way, over what it needs,” says Lee at Populous. “In this stadium, each mode is as good as perfect.”

To the NFL, a game isn’t just a sporting contest, it’s an event, entertainment, a fan experience. As a sport it combines strategy, physicality and athleticism. As an event it is the ultimate stage-managed drama – a short 16-game season, leading up to the big one: the Super Bowl. Fans around the world can find high-quality coverage on TV, the internet, social media.

All this means an NFL stadium needs lights, sound and, most of all, high-tech communications to get all that razzmatazz out to “the thousands in attendance and the millions watching around the world”, as Michael Buffer, the famous American ‘Ready to Rumble’ boxing announcer, used to say.

“The NFL doesn’t want to adjust its operational approaches just to go to a different stadium,” says Jack Treble, a BuroHappold technology expert who worked on the Spurs stadium. “They need a lot of technology and systems that sit alongside the sporting match itself.”

In the Spurs stadium, that means receivers in the roof to pick up information from sensors in the players’ jerseys and send it to analysts’ laptops at pitchside, and an IT system that enables the NFL to operate their sky cam and Spurs, their Champions League spider cam. “Pitchside advertising boards open to enable NFL players to run on from the right part of the stadium,” says BuroHappold engineer Hannah Davy. “The media area can be redesigned to fit cameras and platforms into the places needed to follow an NFL game, which when in football mode are covered by seats.”

Treble adds: “The stadium has spaces for each sport and then flexible spaces that can be set up for either sport.”

The stadium’s audio-visual system is also designed to accommodate both sports. The sound system uses loudspeakers and also sub-woofers to provide a low-frequency enhancement. High-quality integrated audio, video and lighting help drive the kind of emotion and atmosphere people want during a match.

“It gives the stadium the sort of rock and roll feeling that the NFL likes,” says Eddie Thomas, director at SSE Audio Group, who designed and installed the audio system.

He adds: “Announcements and video footage sit on different networks, so we had to design a software plugin to allow the different technologies from several manufacturers to work together on the single-network platform.”

Thomas believes this is one aspect of the Spurs NFL project that could quickly catch on at stadiums across the UK. “A lot of money comes from corporate hospitality,” he says. “People want to be able to play iPhone music in boxes, interact with TVs and choose their own channels.”

Former England cricketer Kevin Pietersen once told me that T20 cricket will eventually replace five-day Test and domestic three-day cricket, because T20 is more entertaining and that’s what modern fans want. Whether watching Johnny Ordinary and his mates smashing a few fours and sixes on pitches that are rigged to suit the batsman is more entertaining than watching, say, Pietersen blast 150 on a spinning pitch in Sri Lanka, where no other English player can lay bat on ball, is open for debate.

Not everyone watches sport for its finer moments, and whether diehard fans like it or not, sport now competes for people’s time and resources against theme parks, cinema complexes, other family days out, and, of course, against televised sport.

This, inevitably, is changing the way sport is delivered to live audiences, even in a place like the UK, with its tribalistic sporting culture.

“Over here you’ll get a backlash even when stadiums are renamed,” says Dr Alex Fenton from Salford University, an expert on football and social media, “but if there’s a market for it, it’ll happen whether fans like it or not.”

Already we have cheerleaders at rugby league games, US-style drafts in cricket, and LED screens as pitchside advertising boards. There will be more of this change as sport tries to engage with new generations of fans brought up on social media, American TV and online culture.

Football’s controversial VAR system, for instance, might lend itself to using big screens or fans’ personal devices for replays as video-refereeing decisions are being made. Once the sport’s rule-makers choose to make the referee’s decision-making processes more transparent to the public, that is.

Fenton thinks that beacon technology, enhanced stadium Wi-Fi and Bluetooth with better apps will be essential in the near future, to enable clubs to gather data about what their ‘customers’ want from their ‘stadium experience.’

“There’s scope within the stadium design for Tottenham and NFL to incorporate new innovations as they become available,” says Treble. “Enough space, cabling infrastructure, positions to plug things in, bandwidth on the network can be upgraded.”

Some of these technologies might start appearing more quickly should the NFL decide to run a London franchise from the stadium. Hopefully, Spurs would have won a few more football matches by then, too.

The basics

A beginner’s guide to NFL

• A match lasts four 15-minute quarters, with each team allowed three timeouts per half.

• The ball is oval.

• Eleven players from each side on the field at any one time, but a team is made up of 45 players, with different roles.

• NFL teams are allowed unlimited substitutions

• The offence: A team’s attacking players, who attempt to move the ball forward and score touchdowns.

• The defence: who stop the other team from scoring by tackling the ball-carrier, intercepting passes or causing fumbles.

• Special teams who play in kicking situations.

• One team gets four chances (downs) to advance the ball 10 yards, to get another four chances, with the ultimate aim of getting the ball into the opposition end zone and over the goal line for a touchdown.

• This is achieved by either running with the ball until tackled, or throwing the ball downfield to a team-mate

• Most scoring comes from near the defending team’s end zone. A touchdown can be scored from anywhere on the field.

• If the offensive team fails to move 10 yards within four downs, they lose possession.

• Touchback: When the ball travels into or is downed in the end zone following a punt or kick off. The ball is then placed on the 20-yard line for the receiving team’s offence to start their possession.

• Plays are called by the head coach or quarterback.


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