Human Flower Project

106 Million Players:  Super Turf ‘08

James Wandersee and Renee Clary give us the scoop on the Super Bowl’s portable field-in-a-pan. No matter which team wins, this history of athletic turf is unbeatable. EarthScholars, Rah!


Archimedes applying his (super) lever to the globe

Image: via Chris Rorres, Drexel University

By James H. Wandersee and Renee M. Clary

EarthScholars™ Research Group

Archimedes, the ancient Greek mathematician and inventor (280-211 BCE), once boasted, “Give me a place to stand and I will move the Earth.” He was, of course,  talking about his levers as force multipliers and the amazing things they could do.

Surely Archimedes was exaggerating about moving the Earth, though.  No machine could ever do that.  Or, could it?

On February 3rd, 2008, the world’s television-viewing public will have a chance to see the first-ever Super Bowl to be played within a new kinetic architectural marvel—a stadium designed by Uni-Systems® to make the Earth literally move—at least a good chunk of it!

The new University of Phoenix Stadium in Glendale, Arizona, is a modern sports wonder, not only of stadium design, but also of horticulture and turf-grass science.

Given the stadium’s location in the warm Southwest, heat build-up, high humidity from the plants’ transpiration, and uneven sunlight reaching the field through the roof aperture would certainly limit the arena’s usefulness if Bermuda Grass and Ryegrass turf were grown inside this dome.  The stadium would also require supplemental incandescent lighting (as does the Bull’s Eye Bermuda Grass used in the Arizona Diamondbacks’ baseball-only-facility, Chase Field,  in downtown Phoenix). But University of Phoenix Stadium is the first dome to have—along with a retractable roof and full air conditioning—a retractable 94,000 sq. ft., playing field of living grass!

The retractable field scoots on nearly 550 traction-drive wheels, riding upon 13 rails embedded in the concrete floor. Guide wheel assemblies on the center rail maintain the field’s alignment as it moves in and out. Seventy-six one horsepower motors drive the field through the stadium’s southside doors at a rate of about 11 feet per minute (1/8 mph).

CMX Sports Engineers designed the field to react like a traditional grass playing surface, so that players feel safe, comfortable, and confident, whether they are running, jumping, fielding, or tackling each other. At the throw of a switch, the 9,300-ton retractable grass playing field can be moved into the stadium for a football game. The 2.1-acre field relocates into or out of the stadium in approximately 1 hour.


The “Grass on a Pan” Growing Outside the Stadium

Photo: Uni-Systems

On non-game days the playing field rolls from the stadium on a 19-million-pound tray, residing outside where Arizona’s typical sunny conditions are ideal for maintaining grass. The immense pan-type “pot” has all components needed for healthy grass—irrigation, drainage, and an optimized growing medium. The grass grows on top of a foot of sand; under that is the irrigation plumbing, and beneath that plumbing is the tray liner that prevents the water for the field from leaking onto the wheels and power train. Archimedes would surely be impressed!

This “grass on wheels” design provides an attractive space for non-football event planners. The field moves on steel rails that sit nearly flush with the facility’s floor, a low-profile with the grass surface a mere 42 inches above the concrete. After the field rides outdoors, a clean, flat event floor is exposed with ample electrical outlets, fully ready to support non-cleat foot traffic to booths and other displays.

imageUofP’s $455 Million Stadium

Shimmers in the Arizona Sun

Photo: ESPN

Best known as the home of the NFL’s Arizona Cardinals and as the site of the NCAA’s Tostitos Fiesta Bowl, the building is not actually university property but a municipal sports arena whose naming rights were purchased by the for-profit University of Phoenix for marketing purposes.  Unlike most universities, University of Phoenix does not have an extracurricular sports program—yet sports are commonly a source of pride for university alumni. The school agreed to pay about $150 million for the 20-year naming arrangement, shortly after the Stadium was built in 2006.

When the grass field sits outdoors, the indoor stadium can be configured for a multitude of events: conventions, rock concerts, rodeos, and monster truck contests.  The University of Phoenix Stadium’s architects intentionally designed a multi-purpose dome, available for hosting various events 365 days a year, not exclusively a football stadium.

imageGolden Barrel cactus, Echinocactus grusonii

Photo: Priit Pensa

Its shape was inspired by the barrel cactus to announce its location in this Southwestern US desert city. Glendale receives an average of 306 days of sunshine per year.

The roof has two large retractable panels that can uncover the entire playing field or provide maximum shading for fans. In the hot months, the roof can be closed and the dome air-conditioned; in cooler months, the roof can be opened to take advantage of the Valley’s world-famous comfortable climate. 

It should be noted that the first domed sports stadium was the Houston Astrodome. Judge Roy Hofheinz conceived of such a structure in 1952 when he and his daughter were rained out of a minor league baseball game;  the little girl asked her Dad: “Why can’t they play baseball inside?”

Hofheinz succeeded in building such a place in 1964—an 18-story-high, 710-ft diameter, air-conditioned dome! He also convinced Major League Baseball to send a franchise to Houston where, in this building, the weather would always be perfect. The dome even changed the initial name of the team. On April 9th, 1965, the Houston Colt .45s became the Houston Astros, introducing indoor baseball to the Astrodome fans and the nation.

The Astrodome opened with a natural Bermuda grass playing surface. Could natural grass grow in a stadium with little natural light? Since no good data were available at the time, a special greenhouse was constructed at Texas A&M University to test five different types of grass grown under low light conditions. A variety called Tiffway Bermuda grew the best and was subsequently planted in the Astrodome.


Houston Astrodome Configured for Football, 1965

Photo: EB

The dome’s ceiling contained 4,596 semitransparent plastic panes made of Lucite ®. Players quickly complained that glare coming off of the plastic panes made it impossible for them, even with sunglasses, to track high fly balls on sunny days.  The Astros surely didn’t want to play night games only. So all of the roof panes were painted over. This solved the glare problem, but, for lack of sunlight, it also killed the grass. For most of the 1965 season, the Astros played on green-painted dirt and dead grass! Baseballs hit into the outfield turned green. The Astrodome was about to become a sports fans’ joke—and then Astroturf was invented.

Artificial turf first came to major sports in 1965, when AstroTurf® was installed in that newly-built “wonder of the sports world”—the Astrodome in Houston, Texas. The use of AstroTurf® and similar surfaces became widespread in the 1970s, installed in both indoor and outdoor stadia for use by baseball and gridiron football teams in the United States and Canada. Maintaining a grass playing surface indoors, while technically possible, was often prohibitively expensive; teams that chose to play on artificial surfaces outdoors did so because of reduced maintenance costs and uniform surface coverage, especially in colder climates.

When turf toe became a sports injury commonly associated with playing on artificial turf, both the base and the fibers of artificial grass had to be improved. In addition, friction between skin and some types of artificial turf caused abrasions and/or burns to a much greater extent than natural grass did. This was an issue for some sports like football, where sliding is common and uniforms don’t fully cover the players’ limbs. More improvements were needed. Also, artificial turf tended to be much hotter than natural grass when exposed to the sun. Plants self-regulate their temperature, artificial turf does not. Again, engineering innovations were required.


The Anatomy of Astroturf XL

Image: Muhlenberg

Astroturf®  is now in its 12th generation—from its original instantiation as ChemGrass by Monsanto, The short, scratchy, stiff, brush-type turf of past decades has been vastly improved. After many scientific studies of how players and balls move on real grass, it took lots of specialized machinery to manufacture and texturize an artificial grass that mimics the behavior of the real thing. Special sports footwear has also been designed for playing on it. Today’s Astroturf®  is much longer and more lush, its fiber materials have been improved and its multi-layered base is now gently padded with rubber pellets. Today, a sister product, AstroLawn®  is even used for architectural landscaping where natural grass is hard to grow.

Bottom line: It has taken over 40 years of research and development and countless patents to imitate natural grass satisfactorily, to make an artificial turf suitable for use on playing fields, without altering the nature of the game. Although these nylon and/or polypropylene fiber-based surfaces are quite expensive, they solve the “grass won’t grow well here” problem.  For example, with more than 3,000 installations and more than 225 million square feet of Astroturf® produced worldwide, on every continent and in more that 50 countries, it’s hard to deny its impact on sports—and that’s just one brand of synthetic turf.

However, indoors or out, many players still prefer to play on natural grass wherever it’s well-tended. Artificial turf injuries have ended playing careers. “It [artificial turf] should be banned,” Eagles defensive end Clyde Simmons said. “If they want to do something good, they’d get grass in here.” In contrast, some players actually like artificial turf because it allows them to run faster.

Concerns about the environmental impact of artificial versus natural grass playing surfaces continue. Both create a large amount of water run-off, adding to drainage loads. Chemical processes are used in the manufacture of raw materials for artificial turf, and harmful chemicals may leach-out over time. Conversely, biological grass in stadium applications requires potentially harmful chemicals, too, in the form of fertilizers and pesticides for maintenance.

Beginning in the 1990s, natural grass playing surfaces began to make a comeback when the marketing of nostalgia in professional sports resulted in the return of outdoor stadiums. Universities subsequently found that they were able to recruit better athletes if they could offer them a natural grass playing surface.

This series of photographs from Auburn University demonstrates the complexity of restoring a natural grass playing surface in a major football stadium. 

There are thousands of varieties of lawn grass, each adapted to specific conditions of watering, temperature, and sun/shade tolerance. Just as chemists and physicists continue to improve artificial turf, grass breeders continue to develop new and improved varieties of turf grass species.

An interesting recent development has been the hybrid playing surface of synthetic and natural grass. Once artificial turf is installed, it is top-filled with soil. Grass seed is planted in that soil, then grown to a height above that of the artificial turf. The resultant playing surface combines the look and comfort of natural grass with artificial turf’s resilience and resistance divots and gouges. Unfortunately, the hybrid also requires all the maintenance of both turf systems and it’s unsuitable for most indoor applications. Advances continue.


Inside the University of Phoenix Stadium, Site of Super Bowl XLII—2008

Photo: Lectrosonics

Turf management isn’t typically a career that high school students consider, but it is a growing and rewarding field— one that includes the benefits of working outdoors. One can actually pursue a major in Turf Management at several US universities. Turf Management students learn how to plant and care for lawns, parks, recreation areas, golf courses, and athletic fields. Classes address horticulture, botany, biochemistry, agronomy, planting, transplanting, and caring for grasses and related plants, irrigation, and landscape design.

Cristina Milesi, who has estimated that there are 40 million acres of lawn growing in the US, points out that turf is our nation’s largest irrigated crop. Americans do enjoy their lawns. Now about 2.1 acres of it can go indoors to play or move outdoors to maintain its vitality.  In addition to watching the New England Patriots and the New York Giants play in the 2008 Super Bowl, don’t forget to take a look at the ~106 million blades of natural grass making those great plays possible, and providing a backdrop for all the action!  Move the Earth, Archimedes? Indeed!





Posted by .(JavaScript must be enabled to view this email address) on 02/02 at 01:31 PM


Wow! I had no idea that the grass could be wheeled in and out. My son read too, because he’s a big football fan.

It is really neat that the stadium was fashioned with the shape of the barrel cactus in mind!

Posted by kate on 02/02 at 05:39 PM

A fascinating article!  I have read much about lawns in residential settings, but fewer about lawns in other settings, thank you. 

Parks departments struggle with the issue of turf versus lawn.  In Pittsburgh, the Pittsburgh Park Conservancy used an athletic and golf course soil profile for the 1-acre lawn in Schenley Plaza to withstand daily and varied uses.

Posted by Georgia on 02/02 at 07:03 PM

cool hmm aha! at last a solution for my weed loving front yard - i’ll just astroturf the whole damn thing - then, no grass cutting or maintenance - but, one question does remain - do dogs still do their business on astroturf?

Posted by .(JavaScript must be enabled to view this email address) on 02/04 at 08:06 PM

Yes, the synthetic grass will be definitely safe for sportsman as it has the shock absorbing capacity .

Posted by Shawn on 02/18 at 04:02 AM
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