Tennis Technology

Racquets aren't the only components to alter the way tennis is played. Today, the sport's most significant variable is the type of surface installed.

"With the exception of the tiebreaker, the rules of tennis have hardly changed over the past 100 years. However, technological advances in the tennis industry have changed the complexion of the game dramatically. Advances in everything from racquets and balls to tennis shoes and court surfacing have made the game significantly faster and more punishing to the body. The tennis facility developer must be aware of these changes in order to build the most attractive and player-friendly court possible.

Today, the game's most significant variable is the type of surface installed. The type chosen for an outdoor court will depend on a variety of factors - the amount of play on the court, players' skill level, the construction budget, the maintenance budget and the physical limitations of the site. The latter might include climate, irrigation capabilities and space. These factors should be evaluated prior to choosing a court surface.

Outdoor tennis courts can be classified into three general surface categories - grass, clay and hard. Indoor tennis court surfaces include those used out-of-doors as well as carpet-type prefabricated systems, clay-like indoor systems using rubber, and rollout playing surfaces. Each type of surface has advantages and disadvantages, so a court specifier must weigh the pros and cons of each. Grass and clay courts are more comfortable for the tennis player but are more expensive to construct and maintain. Hard-court surfaces are more economical in both the long and short term, but are more punishing to the player.

The grass category includes both natural and synthetic grass surfaces. Natural grass, the original surface used for tennis play, is by far the most luxurious and is most widely associated with Wimbledon. Because of the natural resilience of a grass surface, this surface is very forgiving to the body and comfortable to play. On a well-maintained surface, glare and dust are nonexistent.

However, the grass surface is expensive to install, costly to maintain and very vulnerable to weather. Grass courts are slow to dry after rainfall events, and are very slippery when wet. A grass surface may also negatively affect play; if not maintained properly, uniform ball bounce could be compromised by imperfections in the ground.

Installation and maintenance costs are high because of the vulnerability of natural grass to foot traffic. Tennis matches are typically staggered on grass courts to provide time for the grass surface to recover from damage caused by play. As a result, the amount of space (that is, the number of courts) required for continuous play exceeds that for other surface types.

Certain manufacturers are producing and marketing a synthetic grass tennis surface to offer the look of a grass surface while providing the comfort of a cushioned playing surface. This kind of surface is typically manufactured with a short-pile synthetic fiber filled with sand and laid over a shock-absorptive cushioning system. Because of the artificial nature of this surface, the system can be installed to provide relatively consistent bounce and cushioned comfort without the slickness of a natural grass surface. While maintenance costs are lower than those of natural grass, synthetic-grass installation can be quite expensive and its life expectancy is somewhat limited.

The expense associated with the installation and maintenance of traditional grass courts is what initially led to the development of clay courts as an alternative surface. This category of surfacing includes local natural clay, fast-dry (granulated stone) and even ground brick. The early clay court was difficult to play on because of glare, long drying time and lack of traction when wet However, at optimum moisture levels, the natural clay surface is the least demanding on the player. It will provide slide in the player's game, thereby reducing the transfer of shock in the feet and legs caused by sudden stops.

Over the past several years, manufacturers have developed an artificial "quick-dry" or "fast-dry" type of court surfacing. This surface is composed of a drainage layer under a manufactured-clay playing surface. The drainage layer improves the drying time of the playing surface by removing the water from the court by means of a granular base material and drainage piping. This base course provides moisture to the fast-dry surface during play. The surface layer is typically composed of clay, crushed rock, marl (in France and Switzerland) or ground brick depending on the geographical area in which the court is constructed.

Because of the fine, granular nature of the fast-dry court, this surface must be irrigated frequently. Many courts are irrigated on top of the surface by hand or by above-court sprinkler systems. New technology in fast-dry court construction provides a surface that is irrigated from below the surface. Utilizing irrigation piping below the badly material, the granular base acts as a controlled water reservoir, using the principles of evaporation and capillary action to maintain a constant and uniform moisture content in the surface layer. The irrigation system is equipped with overflow devices to shed excess water after rainstorms.

The fast-dry court surface is more expensive to install and maintain than most hard-court surfaces. Regular maintenance is required to maintain a true and consistent bounce. In some extreme climates, the irrigation system must be drained over the winter to prevent freezing and damage to piping.

Hard courts range from asphalt or concrete covered with a color coating to acrylic, vinyl and rubberized hard-court surfaces. The type of pavement selected for a hard-court surface will be determined by evaluating local soils, the water table, cost and site conditions. An asphalt pavement is most commonly used; however, in extreme cases where unstable sub-soils are evident, post-tensioned concrete is used to maintain the structural integrity and planarity of the playing surface.

Hard courts are typically installed in public parks and other high-traffic areas where minimum maintenance is a primary concern. They can be the least expensive type of surface to install and require the least amount of maintenance.

This surface is, however, the most punishing to the player's body because of the lack of slide characteristics provided by grass and clay courts.

In an effort to reduce the shock experienced with hard-court play, the tennis industry has developed numerous cushioning systems that are applied directly over the pavement surface prior to coloring the court. These include granulated rubber, rubber mats, cork and shredded cane fibers, the installation costs of which vary dramatically.

The advantages of a cushioned hard-court surface include low initial cost, low maintenance cost, true ball bounce, low glare, quick dry time and sure footing for the player. There are, of course, disadvantages to using this type of surface. It retains heat for a longer period of time, it causes players more foot and leg stress, and is more prone to damage from misuse. It should also be noted that small repairs to the surface are not easily hidden.

Indoor tennis courts frequently feature the same surfaces as outdoor courts. In addition, one of the most predominant indoor surfaces is the cushioned asphalt subsurface with an acrylic overcoating.

Indoor courts' protection from the elements makes other surface systems that cannot be used outdoors viable. These are usually prefabricated surface systems, such as a carpet-type surface that is pre-manufactured and rolled out on the court surface. Carpet surfaces come in a variety of styles - smooth, textured or grass-like. Because they are not subjected to rain, snow and hot and cold temperatures, they can be manufactured more like carpets, providing a minimal frictional coefficient between the shoe and the surface. This type of surface will play more like a natural grass court.

There are also indoor court surface systems that are clay-like in appearance and playing characteristics. These are composed of synthetic rubber granules on a carpet-like substrate that tends to resist the sliding of the granules, thereby producing a slide rather than a slip.

Some indoor surface systems are manufactured to permit them to be rolled out for tournament use and then re-rolled and stored, or moved to another site. These systems tend to be developed to have specific playing characteristics to satisfy the needs of a specific tournament or a particular playing requirement. Some of these courts come already lined, making them available for a quick rollout in preparation for play.

Many players like the feel of playing tennis on a clay court, even indoors, and the development of subsurface irrigation systems have made the use of fast-dry courts more practical for indoor applications. The benefits of installing fast-dry courts inside include players' ability to slide and a reduced friction coefficient. However, there are some drawbacks to using this surface indoors. In an indoor environment, this surface will react differently than in an outdoor environment. Ventilation, air flow, heat flow and other factors that affect the drying of the court surface can often result in non-uniform playing characteristics on the court surface. Other disadvantages of a fast-dry indoor court include excess humidity that tends to adversely affect the structure of the building, the tendency of the surface material to be tracked through the clubhouse and difficulty in controlling the amount of moisture on the court surface.

Choosing a court surface really can be a challenge for a tennis facility developer. Specifiers must look at so many factors - climate, level and frequency of play, site location and player needs. For example, if players are accustomed to the comfort and slide of a clay court surface, a hard court will obviously not be an appropriate surface for consideration. If water is not available for irrigating a court, water-dependent systems like grass and clay will not be an option.

Developers must also consider the style and frequency of play. Remember that while some surfaces such as grass are beautiful to the eye, these delicate systems cannot withstand the stress of constant play. Surfaces in public spaces and parks should be able to withstand the punishment of skateboards, bikes and in-line skates. When considering delicate surface systems, make sure to include life-cycle and maintenance costs in your deliberations. Ultimately, of course, budgetary constraints will impinge on the type and quality of the system selected.

Additionally, many other details will influence your surface decision such as court location, orientation, access, sub-surface evaluation, drainage, lighting and player support facilities. A tennis facility consultant can help sort through the many surfacing and materials options, providing valuable guidance about the type of facility best suited for the anticipated clientele, climate and playing conditions. A consultant can provide a design that conforms to the rules of the game while protecting the developer from litigation caused by unsafe court installations.

It is also important to seek experienced and reputable tennis court contractors who specialize in the application of the various court surfaces. While site preparation and installation of support facilities can be completed by a general contractor, a specialized tennis court contractor should be used to ensure that court surfaces are constructed within the tolerances dictated by the tennis industry.

by David LaSota and Sheldon Westervelt, P.E.