Research Breakthroughs

Allen Cudworth

Under the leadership of Charles R. Williams, Ph.D., (1961-1964) and Allen Cudworth, Sc.D., (1965-1990), Liberty Mutual investigators forged new directions in occupational health and safety. Then, as it is today, manual materials handling was the leading cause of occupational injury in the United States, comprising approximately 35 percent of all workers compensation claims annually.  Using data collected

Manual Materials Handling Investigation

from numerous controlled studies of simulated, industrial material handing tasks, researchers produced tables of maximum acceptable weights and forces that workers can lift, lower, push, pull, or carry without excessive fatigue. These tables resulted in widely accepted manual-handling task guidelines. These guidelines help practitioners design tasks to decrease the risk of work-related injuries and disabilities.

The data also formed the basis for CompuTask^TM, an ergonomic analysis software tool used today by Liberty Mutual's loss prevention consultants to evaluate manual-handling tasks. Researchers continue to make software improvements including a module for evaluating upper-extremity repetitive motion exposures.

The first Horizontal Pull SlipmeterTM

Slips, trips, and falls comprise another leading cause of occupational injuries. The U.S. Bureau of Labor Statistics has reported more than 250,000 disabling injuries resulting from a work-related slip, trip, or fall each year since 1996. Even before such statistics were available, Liberty Mutual recognized the significance of slips, trips, and falls as an occupational hazard. In 1967, Liberty Mutual researchers developed the first Horizontal Pull Slipmeter^TM, a portable device that measured the slipperiness of floors and other walkway surfaces. This tool gave safety practitioners and researchers a way to evaluate floor slipperiness and devise prevention strategies. Early slips and falls research included investigations of floor surface testing methods and cleaning protocols. Today, research includes tribological studies of the interaction between shoes, contaminants, and floor surfaces; biomechanical investigations of human gait, stability, and motion patterns; and cognitive studies of human perceptions and decisionmaking processes. Findings from these studies provide a scientific basis for workplace innovations that can reduce the likelihood of a work-related slip, trip, or fall.

Repetitive Stress Research

During the 1980s, the Research Institute broke new ground in repetitive stress research. Researchers began a series of controlled experiments in which subjects performed simulated light assembly work, manual screwdriving, and knife-cutting tasks. The data from these experiments helped to establish the maximum acceptable forces for repetitive wrist motion with different wrist postures and grips. These studies also inspired the later development of the Musculoskeletal Stress Measurement Kit^TM. Patented in 1994, the kit allows users to accurately evaluate repetitive-motion hand tool exposures. Instrumented knives, pliers, and screwdrivers transmit information to a special computer that plots the torque output exerted by a worker. Researchers and practitioners use the instrumented tools to gather data for analysis with CompuTask software to reduce upper extremity injuries.

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