Feature Article - May/June 2003
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Tread Lightly

A complete guide to selecting the right sports surface

By Margaret Ahrweiler

Artificial turf

Artificial turf, which most manufacturers now call synthetic turf, has come a long way from its introduction in the 1960s, with a great deal of biomechanical research, product development, testing, chemical tinkering, number-crunching and more testing undertaken to make it more forgiving to athletes' bodies and more similar to natural turf.

University of Texas at Austin

As an indication of how far turf has come, FIFA, the International Soccer Federation now states it is "very much in favour" of the use of artificial turf in harsh climates and in stadiums where it is hard to grow and maintain natural grass. The most sophisticated turf systems mimic the grass's response to players and balls, in the way it deforms, in its slip resistance, and in its ball bounce and return, among other things.

Manufacturers have developed a number of different systems and grass fiber and shock-absorption types to try and replicate these responses. The two most common systems are conventional, or sandless systems, applied on a concrete base, and infill systems, applied atop sand or dirt.

Grass fibers, which can be made of polypropylene, nylon or a blend of the two, can be assembled in several ways. Some systems knit fibers together. While more expensive, Johnston says this method is more stable. Others feature fiber "tufts," similar to what carpeting looks like. Some products even feature shock-absorbing infill materials between each fiber to mimic the play of grass.

In addition to the turf fibers, several options are available for the underlayers. For the padding underneath, shock-absorbing assemblies include closed-cell foam pads, SBR rubber sheets, or cast-in-place elastic materials, called an e-layer. A turf system can even incorporate all these. More basic methods depend simply on the underlying infill to provide shock absorption.

The next consideration is installation methods. When installing the turf mats, the seams can be glued or sewn together. Glue requires less expertise and costs less, while sewn seams are more expensive but can provide a superior finish. Finally, the striping can consist of painted lines, which are less expensive and easier to change, or inlaid lines, where are more permanent and durable, but can create additional seams in the turf.

And while synthetic turf requires no mowing, watering or fertilizing, it brings its own set of maintenance issues. If water is the mortal enemy of outdoor running tracks, turf's mortal enemy is the sun's ultraviolet rays. UV rays can reduce the fibers' strength, make them more brittle and discolor the turf. Other wear issues include compaction of underlayers, seams wearing through and fiber loss, just as a carpet gets bare spots.

Playing it Safe
What you should know about playground safety surfaces
Top: The safety surfacing at the Enchanted Hills playground in Rio Rancho, N.M., looks like wood fiber but is actually a new safety surfacing made from recycled tires. Above: Blackhawk Family YMCA in Waterloo, Iowa, converted a racquetball court into a fun play space for pre-schoolers.

Indoors or out, the need to cushion children's playground bases is well documented. Playground surfaces must conform to ASTM standards on impact attenuation, or cushioning, and accessibility, to meet guidelines for disabled users. The International Play Equipment Manufacturers Association (IPEMA) has worked with the ASTM and the U. S. Consumer Product Safety Commission to create stringent guidelines for play surfaces as well.

Outdoors, wood chips remain a hands-down winner as a safety surface but they've evolved far beyond the leftovers from a village forestry program. IPEMA specifies engineered wood fiber, which takes wood chips a step further, grinding them to a fibrous consistency that lets the material "knit" together for greater cushioning and safety, says Ted Illjes, chairman of the surfacing certification committee for IPEMA. The CSPS sets guidelines about wood fibers' depth.

Synthetic outdoor materials include rubberized sheet goods or tiles made of either EDPM or SBR, with a cushioned surface made of rubber shavings underneath, or a surface shredded rubber or even foam. These materials are rated according to thickness required for a drop height—an 85-mm-thick rubber tile may be rated for an 8-foot drop height, for example. Beyond cushioning, the surface's response to weather conditions must be taken into consideration. Facility managers need to take into account how a surface may handle humidity, freeze/thaw cycles, and whether or not the surface retains its resiliency in the cold.

For indoor playgrounds, rubber also prevails, with pads or a granular-based surface similar to those found in weight rooms. BSA's Ross prefers granular rubber sheets goods to simulate the outdoor environment more and because playgrounds should provide all-around sensory experiences from ceiling to floor. The same ASTM standards for playground surfaces, with thicknesses according to fall height, apply indoors, Illjes adds.

IPEMA's web site, www.ipema.org, provides plenty of helpful information, including a list of products certified for playground use, and gives its rating according to thickness and drop height. The CSPS Web site, www.cpsc.gov, also publishes playground-surface standards.

Turf lite?

Turf's advances even offer benefits for natural grass fields. Grounds crews fed up with trying to keep grass fields properly striped can now get line stripes and other markings made of synthetic turf embedded into their fields to provide just a touch of the permanence of artificial turf.

The last word

Outdoors or in, the path to finding the right sports surface for your facility (with its own special mix of users, maintenance issues and budget) can often resemble a maze, with a different surface or system down every alley. But after working with your team to clearly identify your needs, hitting the books and the Web, and talking with experts to educate yourself, the path to the right system will become clear. And after that, it's just a walk in the park.