This month's specifier takes a look at the world below our feet, including the best products, essential points to remember and whole-life costs. But first, the latest in sporting surfaces …
When you think of the latest in sports construction, your mind is likely to turn to Wembley Stadium or Zaha Hadid's 2012 Olympic Aquatic Centre. The humble playing surface, be it tracks, pitches or courts, does not get a look in. But over the past few years, artificial surfaces have appeared that are unrecognisable from their predecessors. FIFA, football's governing body, has recognised this and in August gave permission for top-flight games to be played on certified artificial pitches. New European standards for sports surfaces and a standard for roller sports such as skateboarding are also likely to come into force in the middle of the year, although makers who meet other standards, such as the German DIN standard, are likely to already comply with the European rules. Although we mention a few of the makers of the latest surfaces here, the trade body for the industry, the Sports and Play Construction Association, provides a comprehensive list at www.sapca.org.uk.
There's a different kind of pitch invasion happening in football. Gone is the Astroturf of old that gave players friction burns when they performed slide tackles and prompted Queen's Park Rangers to ditch their artificial pitch. In comes the more forgiving "third generation" pitches, which use polyethylene strands for the grass, backed by a latex coat to hold the strands in. Some opt for a thicker rubber base, which also gives some cushioning, whereas others have a thinner latex base with a separate rubber shock pad under the carpet. Shock pad systems are more expensive, but help the pitch to retain its bounce, particularly under heavy use. However, most community groups do not need them. Rick Thorley, the UK general manager of sports surfaces specialist Desso, says: "For a community centre, you do not go for a shock pad as you are not looking for
long-term performance. If the pitch goes a bit hard over time then you can rake the strands and it will still be an excellent pitch to play on."
You can also choose between one fibre per strand of grass or a single fibre split into several strands of grass, but split strands may pull apart after years of heavy use.
FIFA's rules for artificial pitches include limits on how high the ball can bounce, how far it rolls, how far players slide, drainage, the strength of the pitch's seams and the force of the impact as the player hits the ground while running and falling.
Real Madrid, Tottenham Hotspur, Crystal Palace, Millwall, Nottingham Forest and Wolverhampton Wanderers use Desso's DD Challenge Pro or SoccerGrass Third Generation systems in their training grounds. Other companies making third generation pitches include Norden, Tiger Turf, Lano, Berleburger and FieldTurf.
Technology has been able to give good old natural grass a helping hand, too. Rugby and football pitches can now use natural grass but with artificial strands of polypropylene included in the turf every two centimetres. The strands go 20 cm into the ground and give the grassroots something to bind to. This can help to make the natural grass tougher and less likely to be pulled out by boot studs. "You end up with a more level pitch because you don't get undulations caused by grass being pulled out," says Thorley, whose GrassMaster system uses this technology.
This resilience is particularly useful for rugby scrums where the stresses generated by players pushing against each other can tear up the pitch. Inevitably some blades of grass will be pulled out, but the roots should remain because they are bound to the artificial grass. This means new grass will grow and reduces the need for reseeding. In addition, water can run down the fibres and reach the roots of the real grass, improving growth and pitch drainage. The International Rugby Board has pitch standards that include tests such as ball bounce and the strengths of seams on the pitch carpet similar to the rules set by FIFA. Rugby clubs such as Leicester Tigers, Wasps, Saracens, London Irish and Ospreys have Desso's GrassMaster pitches either for training or matches. In football, Liverpool, Aston Villa, Spurs, Manchester City and West Ham all use the system.
Artificial running tracks come in two basic types: liquid resins that are poured and then harden on site, and rubber carpets that are laid. The carpets can be manufactured to precise levels of softness and bounce whereas pouring can inevitably produce a few discrepancies.
Track maker Mondo produced the carpet system tracks for the Sydney and Athens Olympics and for most world championships including the one held at Birmingham Indoor Arena in 2003. The Mondo track is made from a grid of rubber cells, which compresses and rebounds for energy absorption and return. This is covered by a hard wearing embossed coating that allows water to run off so the track retains its traction in the rain and is resistant to damage from spikes. Other firms making synthetic tracks are Polytan, Charles Lawrence, Conica Technik, Berleburger and Nordon.
It is important to work out who the main users of the track will be in order to decide how much the surface should give and spring back under the athletes' feet, a process known as force reduction. Top athletes want a fairly hard track in order to get maximum speed, although they need some cushioning to protect their joints. Children will be less bothered by split second speed differences but their growing bodies will need protection from impact. The governing body, the International Association of Athletics Federations, also has rules on flatness, slip resistance and the amount the track compresses under each step.
Although skateboarding has not yet made it to the Olympics, the number of skate parks is rapidly expanding. Skate ramps can be surfaced in a choice of four main materials: timber, steel, concrete and composites.
Composite surfaces are the new kids on the block, and a number have been designed for skateboarding. One, RhinoTop, is made by Rhino to coat its wood and laminate framed ramps. It is made from a series of resin-coated paper layers that are heated and compressed. The surface is designed to marry durability, flexibility and low noise - the ramp is certified to emit less than 50 dB from 10 m away. The surface is resistant to the impacts of skateboards landing on it, is gouge proof, does not cause friction burns when skaters fall, but has good grip.
Chris Dodd, director of Rhino, says: "Every part of a skate ramp will have somebody skidding across it at some point so it is important that the meeting points between components are smooth." There are other considerations when building the ramps, such as safety rails and enclosing the underside of the ramp to prevent rubbish (and people) from collecting underneath. Other firms making ramps include Blakedown Sport and Play and Hags Play.