Impact Attenuation Testing for Trampolines & Inflatables Expert Article

One of the most common injuries that occurs with trampolines and inflatable amusements is for patrons to forcefully contact the ground or other rigid surfaces. The forensic investigation of these incidents will often consider whether those surfaces were appropriately padded with an impact-attenuating (cushioning) material to provide patrons with reasonable safety.

This article provides a basic overview of impact attenuation as it relates to trampolines and inflatable amusements, including key terms, relevant standards, and how testing is performed to evaluate conformance with standards.

Impact Attenuation

To understand the purpose of attenuating surfaces, it may be helpful to revisit some of the basic principles of physics; Force = mass x acceleration. The goal of attenuating surfaces is to dissipate energy over a greater distance.

Proper attenuation is realized when the forces are minimized to a point where the risk of injury is significantly minimized or eliminated.

Attenuating surfaces are extremely common around sport and amusement activities to protect the user from injury. Some common examples include playground surfacing, padding around football goalposts, and gymnastics landing mats. Despite the similar purpose, different international standards and testing methodologies apply to specific activities and it is important that forensic investigations conform with accepted industry standards and methods.

For information on playground impact attenuation, see our article on Playground Surface Impact Testing.

ASTM F355 Impact Attenuation Standards: Trampolines & Inflatables

Impact attenuation material used in amusement devices is intended to cover hard surfaces that a patron can encounter while using the device and typically consists of foam padding. The foam padding is usually covered with a vinyl shell that protects the foam from environmental elements such as moisture and UV radiation.

The amusement industry has set the maximum shock (Gmax) forces for new and/or in-service materials in both inflatable and trampoline court devices. While the standards governing inflatables and trampoline courts vary, both are tested following ASTM F355.

Per ASTM F2374-22:

Inflatables - an amusement device, used to bounce or otherwise play on, that incorporates a structural and mechanical system. These devices are made of flexible fabric, inflated by one or more blowers, and rely upon air pressure to maintain their shape.

• For commercial inflatables that fall under ASTM F2374, landing areas around the entrances and exits shall meet specified ASTM F355 testing criteria.
• These landing areas shall be covered by impact mats that meet specific Gmax criteria. The mats are placed at the entrances and exits so that elevated patrons who are entering and exiting an inflatable will not come into contact with a hard surface.

Per ASTM F2970-22:

Trampoline Courts - a defined area comprising one or more institutional trampolines or a series of institutional trampolines.

• For trampoline courts that fall under ASTM F2970, all obstructions located within the device use zone and assembly areas shall be padded to protect patrons according to test method ASTM F355.
• This includes areas that have exposed metal such as the trampoline suspension system, frames, hard surfaces, and assembly areas that extend outward from the trampolines.

Testing in Conformance with ASTM F355

Robson Forensic experts utilize the TRIAX TOUCH A-Missile for ASTM F355 compliant impact attenuation testing. The TRIAX TOUCH A-Missile is known to be fully compliant with the ASTM F355 procedure and produces accurate and consistent results in both field and laboratory use.

This process enables our experts to obtain measurements that are both accurate and repeatable from pre-configured impact heights. The equipment is calibrated as per standards by technical experts certified as TRIAXTouch Surface Impact Testers.

Amusement Injury Expert Witness Investigations

The experts at Robson Forensic have investigated hundreds of amusement device incidents. Robson Forensic provides expertise in all aspects of amusement device analysis, ranging from design and manufacturing, to maintenance and operation of the device; including supervision, patron education, training of operators, and inspection.

For more information, submit an inquiry or call us at 800.813.6736.

Featured Expert

Lance Miller

Inflatable, Trampoline & Amusement Device Expert

Lance Miller is an expert in the amusement industry with specific expertise in inflatables, trampoline parks, and specialty devices. He is an active member of ASTM F-24 where he is the task chair for Amusement Challenge Areas focusing on devices such as ninja courses, warped walls, battle beams, aerial silks, and other devices. He is also active on the inflatables committee, F-2374-19.