Development of a test method for evaluating safety helmets' ability to reduce skull fracture and brain injury risk from falls in construction

Abstract

Falls in the construction industry account for the greatest number of fatal and non-fatal traumatic brain injuries (TBIs), however current safety helmet standards do not test safety helmets under impact conditions realistic to this injury event. Safety helmets are broadly classified into two groups: Type I, which are tested at the top of the helmet and Type II, which are tested to the top and side of the helmet. However, even the more protective Type II helmets are not tested at energy levels high enough to be representative of falls, which can occur from a wide range of heights. To evaluate the protective capacity of safety helmets, realistic impact conditions need to be identified to accurately recreate fall events in a laboratory setting. However, this remains a challenge as there are limited studies or videos evaluating head impact boundary conditions during falls in construction. The research presented in this thesis had three primary objectives: to determine the head impact velocities associated with falls from various heights while accounting for reductions in energy due to fall impact mitigating mechanisms; to identify the necessary boundary conditions such as impact surface, impact angle, and impact locations needed to recreate various fall events; to develop and execute a testing methodology that accounts for the previously outlined boundary conditions, and evaluates safety helmets' ability to reduce brain injury and skull fracture risk. The results show that fall-arrest movements associated with bracing can lower the head impact severity from a fall, providing insights into appropriate head impact velocities for safety helmet testing. Through analyzing fall accident reports, performing exploratory oblique helmet testing, and examining previous literature, boundary conditions for recreating falls in a laboratory setting were established. This information was then used to develop and execute a safety helmet testing methodology that evaluates safety helmets for protection against concussion and skull fracture risk. The results of this study demonstrated a wide range of performance across Type I and Type II helmets. Type II helmets were more effective at preventing skull fracture, emphasizing the benefits and reductions in catastrophic head injury risk when wearing a Type II safety helmet for protection against fall scenarios.