QuoteJust as important as the interaction between surface and ball, but harder to reproduce, are the biomechanical properties of the pitch. Most sports require players to perform a range of actions. They have to be able to start, stop and change direction abruptly, sprint, jog and walk forwards, backwards and sideways, jump, slide and fall over.
Most surfaces simply don't support this range of movement, especially when the players are wearing boots with studs on. It turns out that this is because they score too high or too low on at least one of five parameters - shock absorbency, deformability, grip, traction and friction - each of which has a very narrow range of acceptability. For good shock absorbency, for example, the pitch must absorb between 60 and 70 per cent of the energy of an impact. Anything less and players are in danger of getting hurt; anything more and they get tired too quickly. Grip, traction and deformability are equally unforgiving: too low and players lose their footing, too high and they suffer joint and soft-tissue injuries.
“It's hard to know whether the striker's concerns arise from the fear most players feel about artificial turf”After years of experimentation, artificial turf manufacturers claim to have developed two systems capable of mimicking the properties of real turf. The most common type uses polyethylene "grass" about 5 centimetres long, which is lubricated with silicone and sewn into a rubberised plastic mat. The whole thing is then "infilled" with a 4-centimetre layer of sand and rubber granules, which keeps the fibres upright and provides the right level of shock absorbency and deformability. The majority of the 15 or so turf manufacturers approved by FIFA use this technology.
The other sort, typified by Dunfermline's pitch, has a base of expanded polypropylene, a foamy material originally developed as a shock absorber for the car industry (see Diagram). The grass is also made of lubricated polyethylene fibres, but they are shorter and more densely packed than on an infilled pitch, and are also interspersed with short, curly, spring-like fibres that keep the blades upright. The finishing touch is an 8-millimetre filling of rubber granules.
Today's visiting team, Rangers, can't afford to let any unfamiliarity in the pitch affect the game: they need a win to stay in the race for the championship. And they get one, scoring early and hanging on to win 1-0. But that doesn't mean they are happy. At the press conference after the game I ask the goal scorer, Croatian striker Dado Prso, what he thought of the pitch. "It's terrible," he says, "very hard to play."
It's hard to know whether Prso's concerns are justified, or simply arise from the antipathy - and fear - most professionals feel towards artificial turf. But on the latter count at least, players ought to stop worrying. UEFA's injury figures suggest that artificial pitches are significantly safer than grass, with 3.2 muscular and ligament injuries per 1000 playing hours compared with 7.6 on grass.
With the stadium almost empty, I walk onto the pitch. It feels springy and pri.ckly, not like real grass at all. I run a few paces and there's a pleasing sense of both firmness and give. If I had the choice of watching a game here or on a really good grass pitch, I'd take the grass. But it's an awful lot better than many natural pitches I've seen. And ultimately, that's the kind of reasoning that will make or break artificial turf. Sure, a good grass pitch is unbeatable - even the manufacturers acknowledge that. But grass costs money, and that's something most professional sports clubs don't have. The super-rich will always play on real turf. But down at the grass-roots level, plastic looks like an opportunity that's too tempting to miss.
From issue 2502 of New Scientist magazine, 04 June 2005, page 35
Turfed out
IF artificial turf wins over the sporting world, it would be a victory against all the odds. Almost as soon as it made its debut in the Houston Astrodome in Texas in 1966, "plastic grass" acquired a bad reputation. The Astrodome only installed it as a last resort - the stadium's revolutionary roof made it almost impossible to maintain a grass pitch. And even though other football and baseball stadiums followed the Astrodome's lead, artificial turf was never a hit with players or spectators. Many arenas eventually ripped it up and went back to grass.
In Europe, artificial turf's reputation is, if anything, even worse. In 1981, London soccer club Queens Park Rangers dug up its grass pitch and installed an artificial one. Others followed, and by the mid-1980s there were four plastic grass pitches in operation in the English leagues. They soon became a national joke: the ball pinged round like it was made of rubber, the players kept losing their footing, and anyone who fell over risked carpet burns. Unsurprisingly, fans complained that the football was awful to watch and, one by one, the clubs went back to natural grass.
Originally Posted by ThatGuy
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