Turf System Product Testing

Three unique parts of the body produce different impact levels when contacting the surface, so 3 different test devices are used.

We test because safety matters

It’s only when quality shock pads are used beneath infilled turf that the safety levels of natural turf can be achieved for players. We know this from the data collected from the Gmax test, the HIC test, and the AAA foot impact test on fields of all types. This produces a complete picture of how the field is performing from an impact safety standpoint both when newly installed and throughout its lifecycle.

Head Impact Test

Head Injury Criterion (HIC)

The HIC test correlates with the likelihood and severity of a head injury. It has been used for decades in the auto industry and for playground surfaces, and was adopted by ASTM for athletic fields in 2018. The HIC impact test drops a 10.1 lb. hemisphere projectile (curved like a human head) multiple times from increasing heights and determines the surface’s Critical Fall Height. The higher the Critical Fall Height, the safer the surface. A good natural grass field will produce a minimum critical fall height of about 6 feet or higher.

Natural grass critical fall height chart.

Surface Hardness Test

Gmax

The test method covers the measurement of surface hardness. It does not correlate with head injury. Landing on a harder surface transmits more energy to the body so common sense would tell you that a “softer” surface would be better. It’s applicable to natural and artificial playing surfaces. It drops a 20 lb flat missile from 24″. Gmax is a good measurement when used in conjunction with HIC, but as a stand alone test it is not a total measurement of safety. A quality natural turf field will produce a Gmax typically below 115 G’s.

Natural grass Gmax chart.

Foot Firmness Impact Test

Advanced Artificial Athlete Tester (AAA)

This test simulates the heel strike of an adult running athlete in stride. In other words, it measures the softness or hardness underfoot during play on a field. A great natural turf field hits the “sweet spot” of being firm underfoot while producing very low Gmax and high Critical Fall Height. This is why quality natural turf is the benchmark for quality artificial turf.

Natural grass and vertical deformation chart.

The Surface for Athletes

Achieving the proper performance levels for Impacts, Heat and Traction in a quality artificial turf defines modern sports surface design.

Through the application of multiple standardized tests, we’re now capable of creating an artificial surface that closely mirrors natural turf like never before. The areas highlighted in green represent the performance parameters of premium natural turf. The radiating lines illustrate the performance outcomes of the artificial turf field systems outlined at the center. Remember, the height of the turf pile varied between 1.5”-2.0” and comprised products from each turf brand, yet all systems produced optimal performance.

Brock USA PowerBase Pro spoke chart.
Play

Watch Now: See How the Systems Compare

What happens when an athlete’s head impacts the field? Critical fall height testing helps evaluate how a surface manages that impact. A higher critical fall height indicates that the tested system can meet the test’s head impact criteria from a greater drop height.

This video compares test results for three synthetic turf configurations: a system with an e-layer, a system with Brock ShockPad SP19, and a system with Brock PowerBase YSR. Watch how each responds—and why the layers beneath the turf deserve careful consideration during field design.

For architects and field owners, the takeaway is to evaluate the complete system. Ask for test results that represent the turf, infill, and shock pad combination being proposed for your project, and make critical fall height part of the performance conversation from the start.

Design with the athlete in mind. Put the complete system to the test.

Want to see these tests applied to a real field?

Explore the research behind Brock’s impact, traction, and temperature performance.

View Research Library

Turf Field Product Testing: Frequently Asked Questions

Three different testing devices are used because the head, body, and foot interact with a playing surface differently. HIC, Gmax, and Advanced Artificial Athlete testing each measure a different aspect of the complete field system’s response.

HIC testing for synthetic turf measures impact response using a rounded test device and calculates the Head Injury Criterion under prescribed conditions. The results are also used to determine the surface’s Critical Fall Height.

Head Injury Criterion is a calculated measurement of the magnitude and duration of acceleration during a test impact. HIC helps compare how different surface systems attenuate impact energy under the same test conditions, but it does not predict whether an individual athlete will suffer a head injury.

Critical Fall Height is the maximum tested height at which a surface remains within the specified HIC criterion. A greater Critical Fall Height indicates more impact attenuation under those specific testing conditions.

A higher Critical Fall Height means the tested surface provided greater impact attenuation under the prescribed test conditions. It should be evaluated with Gmax, underfoot performance, field age, maintenance, and other system data rather than treated as a standalone guarantee of safety.

Gmax testing measures the peak acceleration produced when a flat impact device strikes the playing surface. The result helps characterize surface hardness and monitor changes in impact attenuation over the field’s life.

No, Gmax does not directly measure or predict head-injury risk. Gmax is a surface-hardness and impact-attenuation measurement that provides more meaningful information when reviewed with HIC and other performance tests.

Gmax testing is not enough by itself because a flat impact device cannot represent every way an athlete interacts with a field. HIC testing and underfoot testing provide additional information about rounded impacts, fall-height performance, firmness, and foot-to-surface response.

The Advanced Artificial Athlete (AAA) test simulates the impact of an athlete’s foot striking the playing surface. It evaluates underfoot characteristics such as firmness, shock absorption, and vertical deformation to help determine how the field may feel and respond during play.

Vertical deformation measures how much the playing surface compresses under a standardized impact. Vertical deformation helps evaluate whether a system is excessively firm, excessively soft, or within the desired performance range for the applicable testing protocol.

The complete turf system should be tested because turf fibers, infill, shock pad, base construction, installation, maintenance, moisture, temperature, and field age can all influence performance. Testing one component alone does not show how the installed system will respond.

A shock pad can affect turf-field testing by adding a purpose-engineered impact-attenuation layer beneath the turf. The shock pad is designed to help manage impact energy and maintain more consistent system performance as the turf and infill age.

No, passing a field test does not mean injuries cannot happen. Testing documents how a surface performs under defined conditions; it cannot account for every athlete, movement, collision, environmental condition, or injury mechanism.

A field should be tested after installation to confirm that the complete installed system performs as intended and to establish baseline measurements. Those results can then be compared with future testing as the field ages.

Synthetic turf should be tested throughout its lifecycle because infill can compact, fibers can wear, maintenance practices can vary, and impact performance can change. Periodic testing helps owners document those changes and make informed maintenance or replacement decisions.

Laboratory results and field results should only be compared when the same test method, equipment, conditions, and reporting procedures are used. Results produced with different devices, drop heights, temperatures, or protocols may not be directly comparable.

Quality natural grass is used as a performance benchmark because athletes are familiar with its balance of firmness, impact attenuation, stability, and underfoot response. Natural-grass performance still varies with soil, moisture, maintenance, climate, and field condition.

Specifiers should request HIC, Critical Fall Height, Gmax, shock-absorption, vertical-deformation, and energy-restitution data when applicable. They should also request testing conditions, applicable standards, complete-system details, aged-field data, maintenance requirements, warranties, and independent documentation.

Brock’s turf-testing documentation includes product specifications, laboratory results, field data, system comparisons, and information about impact, traction, and temperature performance. Contact Brock to request documentation for your field design or specification.

Have more questions about Brock’s Testing?

A Brock specialist can help answer any additional questions you might have in planning your next project.

Contact a Specialist