Biomechanical Assessment of the Implementation of Production Tables on Mast Climbing Work Platforms - CDC
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Biomechanical Assessment of the Implementation of Production
Tables on Mast Climbing Work Platforms
Christopher S. Pan*, Xiaopeng Ning**, Bryan Wimer*, Joyce Zwiener*, Tsui-Ying
Kau***, Mat Hause*, Richard Whisler*, Darlene Weaver*, and Mahmood Ronaghi*
*Division of Safety Research
National Institute for Occupational Safety and Health
1095 Willowdale Road
Morgantown, WV 26505
**Department of Industrial and Management Systems Engineering
West Virginia University
Morgantown, WV 26506-6107
***Quality Analytics
University of Michigan
777 E. Eisenhower Pkwy, Suite 600, Ann Arbor, MI 48109
October 16, 2018
Background
What is a Mast Climbing Work Platform or Mast Climber
• Powered work platform that
climbs a vertical tower
(mast)
• Categorized as one type of
scaffolds
• Can be freestanding or fixed
to an adjacent structure
• Becoming more popular in the U.S. as a way of
replacing traditional scaffolding and ladder
16’’
24’’
Step deck
Conventional Mast Climber
No more step deck unless necessary
Mast Climber with a Production Table
Objective To reduce falls and back injuries by evaluating biomechanically the effectiveness of production table designs for mast climbers
• 15% of fatal falls and 17% of back injuries (nonfatal) in the construction
industry involve scaffolds. Back injuries occupies almost half of work-related
musculoskeletal disorders in the construction industry (CPWR, 2018).
• OSHA fatality and catastrophe investigation summaries specific to mast
climbers (n=35) suggests fatalities associated with the work platform and
that many deaths involve approx. 40% masons (Lincoln, 2011; Pan et al.,
2018).
• Previous studies have biomechanically demonstrated the effectiveness of
engineering designs in reducing back injury and fall-related risks associated
with elevated equipment and manual material handling tasks in the
construction industry (Chiou, 2008; Kim et al., 2008; Pan et al., 2000, 2003,
2009, 2012, 2018).
Method • Twenty-five masonry workers (Age: 33.4±10.1 years; Height: 71.6±2.4 inches; Weight: 191.8±42.3 inches) participated in the study • An instrumented workstation of a typical MCWP arrangement for bricklaying masons was constructed in the laboratory. • The workstation represents a mechanical-equivalent system of a typical MCWP and reproduces dynamic characteristics of those experienced by workers on a representative MCWP.
Currently Used Production Table NIOSH-designed (L Shape) Production Table
spring dampers
spring dampers
(520 lbs per 0.75”)
Distance from Mast 5’ 15’ 30’
Platform displacement 0” .5” .75-1”Method (Cont.)
• 8-camera ViconTM motion capture system (63 markers) and two BertecTM
force platforms were used.
• Independent Variables (Table, Task, and Damping)
• Table (No table, Production table, and NIOSH-designed table (L shape))
• Task (Stepping down, Bricklaying, and Walking)
• Damping (Maximum and Minimum)
• Dependent Variables
• Stepping down forces
• Postural sway velocity and area associated with stepping
down
• Trunk posturesStep-down task (no table)
Step-down task (with table)
Results
Chaffin & Anderson, 1991
Results: Stepping Down Task
Kinetic Measurement (Sway Force, Newton)
Fx: Frontal Plane Sway Force
Mediolateral (left and right)
Fy: Sagittal Plane Sway Force
Anteroposterior (front and back)
Fz: Vertical ForceResults: Stepping Down Task
Kinematic Measurement (Postural Sway, mm/s)
ML: Frontal Plane Sway
Mediolateral (left and right)
AP: Sagittal Plane Sway
Anteroposterior (front and back)Results: Stepping Down Task
Confidence Area (mm2)
CC: Confidence Circle CE: Confidence EllipseResults: Bricklaying Task Acute Back Injury
Conclusion • Analysis supports the use of a production table. Both the use of the existing, industrial production table and L shape table would reduce back-injury and postural-sway hazards while working on the MCWP. • The L shape table could further reduce back injury hazards for bricklaying tasks, if compared with the currently used production table. • Due to the nature of the stepping down task, damping factors associated with weight wouldn’t significantly affect postural-sway and back-injury hazards (experimental limitations). • Other experimental data will be analyzed. These will focus on human behavioral modifications at height, including gait/step characteristics (e.g., speed, step width and stride length) on the MCWP.
Study Partners • François Villeneuve, FRACO • Kevin O’Shea, HYDRO-MOBILE • Jay Gordon, KLIMER • Greg Janda, ALIMAK HEK • Dean McKenzie, Vernon Preston, Jim Maddux, OSHA Construction Directorate • Travis Parsons, Laborers’ Health & Safety Fund of North America • Steve Martini and Bob Arnold, International Masonry Institute • The Masonry r2p Partnership • The Center for Construction Research and Training
Acknowledgement • This project was made possible through a partnership with the CDC Foundation. • We want to express our gratitude to Job-site Safety Institute for their generous contributions to this project via the CDC Foundation. • We would like to acknowledge the contributions of Fraco Inc., which provided the NIOSH researchers with the use of ACT mast climber, an individual work platform, and other technical data and equipment information. • The authors are grateful to Ben Moidel and Max Byron for their valuable assistance with data collection.
NIOSH Disclaimer The findings and conclusions in this presentation are those of the authors and do not necessarily represent the official position of the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention. Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention.
Christopher S. Pan, Ph.D., CPE NIOSH/CDC 1095 Willowdale Rd., MS-807 Morgantown, WV 26505 304-285-5978 304-285-6047 (fax) cpan@cdc.gov
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