August 16, 2018: The new home of Tottenham Hotspur FC has . Spurs' new home, and the new home of NFL games in London, was supposed to open for a September home match against Liverpool. But the project has hit delays, and this week Tottenham said it wouldn't be able to move into its high-tech home until at least October.
A statement said: "Delays are common, certainly for builds of this size and complexity. However, we are hugely frustrated that this has occurred at such a late stage. Whilst we would have been able to mitigate other areas, we simply cannot compromise safety. This decision was unavoidable."
The delay also pushed back of the debut of the stadium's retractable field (explained below), which is meant to make it easy to switch between playing surfaces for soccer and American football. The first NFL game was to be the Seahawks-Raiders matchup on October 14. Now that game has been moved back to London's Wembley Stadium.
July 13, 2018: The world’s top soccer teams want to play on a high-quality pitch made of natural grass. But the London-based club Tottenham Hotspur wants its shiny new stadium to host NFL games, too, and an artificial surface is better for the chaotic wear and tear of American football.
To make one stadium serve both purposes, engineers at Sheffield-based SCX, creators of the retractable roof systems for Wimbledon’s Centre Court, invented something out of the ordinary—the world’s first retractable, dividing pitch, rolling out the natural grass to reveal an artificial surface below.
The idea isn't entirely new. The University of Phoenix Stadium in Arizona, where the NFL’s Arizona Cardinals play, uses a similar strategy. The entire field can slide out of the stadium and into the Southwestern sunshine.
But the technology inside Tottenham Hotspur Stadium takes this a step further. The field splits into three sections for zoned maintenance and allows for the changing of the seats around the field level.
Each of the three lengthwise sections of Spurs’ pitch sits in a 3,000-ton steel tray with rails underneath. Sixty-eight electric motors spin 168 wheels to move each tray, maneuvering them under the south stand to reveal the artificial surface below.
When it’s time to move the soccer field back into place (a 25-minute process), each of the three sections moves independently until lined up. Then they slide inward to join seamlessly, engineers from SCX say. There are 33 individual trays of grass in each section, and every tray has its own under-sod layering. The natural grass fits to the tray for a tight edge, designed to knit the entire field into one unit.
When the natural grass surface in Tottenham slides into place, the touchlines, or sidelines, get transformed, too, as hydraulics raise them even with the field. Tunnel ramps also rise, allowing all three systems—touchlines, ramps and pitch—to meet at the same height.
“This is a massive and complicated moving structure,” says Simon Eastwood, SCX managing director. “All the mechanical and control system engineering skills are in-house and genuinely world class.”
When the natural grass field rolls out of the open-air stadium, the soccer touchline also disappears under the lower bowl, taking with it the first three rows of seats that would otherwise get roped off in a NFL game. The two differing sideline designs were meant to ensure the best sightlines for fans.
Danny Pickard, SCX’s lead engineer, says the technology embodies a true “engineering flair” that will come alive with the world’s newest stadium technology.
Both Kinds of Football
Even after some successful testing, questions remain about how well the tray system will work over time. For years Houston’s NRG Stadium, home of the NFL Texans, tried a removable tray system for natural grass (it wasn’t retractable, as trays were simply picked up and moved similar to arena hardwood floors). Houston abandoned the idea because some trays didn’t create a seamless connection, though the Tottenham system allows for easier care of the grass.
Although Tottenham's success remains to be seen, it won't be an uncertainty for long. Tottenham Hotspur Stadium is set to host its first soccer match in September against Liverpool F.C. visits. Then following month, the Oakland Raiders and Seattle Seahawks will do battle in the 62,000-seat venue.
Both kinds of football will have a new home in London.
Follow Tim Newcomb on Twitter at @tdnewcomb