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Measuring human fatigue with the BLT prototype.

Langley-T; Heitmann-A; Schnipke-D; Ashford-JW; Hansen-K; Bowles-H
Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R44-OH-007664, 2009 Sep; :1-33
During this project investigators conducted three different experiments to validate an alertness testing system developed by Bowles-Langley Technology "BLT". The system is designed to screen workers prior to work to ensure they are not impaired by fatigue or by other factors. Intended users include truck drivers, power plant operators, pilots and others engaged in high-risk activities. Benefits to society include reducing accidents from fatigue or other impairment sources (illness, alcohol, drugs, etc.) and reducing operating and insurance costs. It is estimated that 70% of accidents involve human error with fatigue or impairment as a root or contributory cause. Current industry practice deals with this problem by managing shift work scheduling, educating operators and operator self-monitoring. However, there are no current minimal standards for measuring fatigue and impairment that are practical for actual workplace use. The test developed during this project is a valuable new tool for assessing fatigue in the workplace. To be practical in the workplace a fitness for work test must be short so as not to significantly delay the start of work. A two-minute test is acceptable but a 5 - 10 minute test would not be. In addition, the test should not depend on language skill and should not be excessively difficult. At the same time it must also be valid and reliable in detecting impairment. This project tested whether BLT Alertness Test meets these criteria. The BLT test displays graphic shapes on a checkerboard background. Subjects must determine if all the shapes are the same or if one shape is different. Test time for a 50-item test is about 2 minutes. The scoring algorithm takes speed, accuracy and item difficulty into account and then compares the computed score to a previously established individual baseline score. Thus, each subject's performance is measured against his or her personal baseline rather than in comparison to others. The test incorporates both minimal standards and a permitted baseline deviation both of which can be adjusted as required. Data privacy is managed through PIN numbers and code names with separate passwords for the system administrator and local managers. Each worker/operator is assigned a PIN. The project consisted of three trials intended to achieve three critical aims. The first aim was to determine the relative difficulty of the different possible shape combinations with a goal of improved test reliability. The second aim was to measure validity (sensitivity to fatigue induced impairment) and reliability (test-retest stability). The third aim was to assess the acceptability and feasibility of the system for managers and operators in an operational setting. All three aims were successfully attained. Results indicate that testing for fatigue and impairment in the workplace is both feasible and practical.
Computer-software; Circadian-rhythms; Sleep-deprivation; Drugs; Fatigue; Injury-prevention; Accident-prevention; Truck-drivers; Pilots; Decision-making
Bowles-Langley Technology, Inc., Suite 200, 1801 Clement Avenue, Alameda, CA 94501
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Final Grant Report
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National Institute for Occupational Safety and Health
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Bowles-Langley Technology, Inc.