Thesis
Continuous, direct measurement of material handling carts: characterizing pushing and pulling exposures in banquet workers
University of Iowa
Master of Science (MS), University of Iowa
Summer 2024
DOI: 10.25820/etd.007686
Abstract
This research study examined hospitality workers in the banquet department who routinely push and pull material handling carts as part of their day-to-day tasks. A banquet employee (otherwise known as a houseman) requires the use of material handling carts to transport materials and items needed for event setup to locations throughout the hotel. The work of a houseman is critical to meet all expectations of event setup, such as business meetings, weddings, or annual fundraisers. Future success and profitability of the hotel are dependent on the houseman’s ability to set up, organize, and help the wait staff meet the event needs. However, workers who routinely push and pull material handling carts experience increased risk of musculoskeletal disorders, such as shoulder and low back pain.
Measuring push/pull forces is a key component of managing risks associated with material handling. Widely available methods generally involve the use of hand-held force gauges and simulated pushing/pulling actions to measure both initial and sustained forces. While easy to implement, force gauge-based methods introduce error (i.e., over- or underestimation) and are not able to capture other important aspects of material handling, such as cart speed and the distance traveled.
This study explored the utility of instrumenting a material handling cart for the purpose of direct, continuous measurement of push and pull forces using load cells mounted to the cart handle, cart acceleration using an accelerometer, and both cart speed and direction using a rotary encoder mounted underneath the cart. Four workers were observed during two separate shifts at a local hotel where study procedures occurred. Acceleration, speed, weight, floor type, and the force applied to the cart were collected and observed during the participants’ task. Exposure variables extracted from the time series sensor data included 90th and 10th percentile push/pull force, speed, and acceleration, among others.
Across 205 instances of push/pull interactions captured, the mean 90th percentile push force (i.e., an estimate of maximum push force) was 84.0±44.2 N and the mean 90th percentile pull force was 57.7±41.5 N. All but one of the measured 90th percentile push forces was considered low risk, according to industry accepted exposure guidelines.
Additional results measured the effect of cart weight on the 90th percentile pushing force. For the lowest estimated weight of items in the cart, at <5 lbs, the mean 90th percentile push force was captured at (68.9±27.3 N for full interactions and 75.4±43.8 N for peak interactions). The second group weight 5-25 lb mean 90th percentile push force increased, (84.5±31.2 N for full interactions and 97.1±39.6 N for peak interactions) and the third group weight >25 lb was the greatest, (112.9±47.7 N for full interactions and 103.5±47.4 N for peak interactions). A post hoc pairwise comparison test (Tukey Kramer) identified forces between the weight groups of (>25 lb and <5 lb), and (>25 lb and 5-25 lb) to be statistically significant for both full and peak interactions.
The effect of floor surface on the 90th percentile pushing force was also measured, and statistically significant across both carpet and linoleum tile. It was observed across all 205 interactions that the mean 90th percentile pushing force was greater on carpet for both full (98.2±34.4 N) and peak (109.4±46.5 N) interactions compared to other surfaces (73.4±40.4 N for full interactions and 69.5±33.1 N for peak interactions). The measured forces between the two floor surfaces (carpet and all other surfaces) were statistically significant for both full and peak interactions.
Results will be used to improve the direct and continuous measurement design of our cart and develop additional research questions to address pushing and pulling exposures in the workplace. Ultimately, reducing the burden of musculoskeletal disorders and promoting health and safety during material handling tasks is a long-term objective of this research.
Details
- Title: Subtitle
- Continuous, direct measurement of material handling carts: characterizing pushing and pulling exposures in banquet workers
- Creators
- Alexander Barnett
- Contributors
- Nathan Fethke (Advisor)T. Renée Anthony (Committee Member)Patrick O'Shaughnessy (Committee Member)
- Resource Type
- Thesis
- Degree Awarded
- Master of Science (MS), University of Iowa
- Degree in
- Occupational and Environmental Health
- Date degree season
- Summer 2024
- Publisher
- University of Iowa
- DOI
- 10.25820/etd.007686
- Number of pages
- xi, 66 pages
- Copyright
- Copyright 2024 Alexander Barnett
- Language
- English
- Date submitted
- 07/22/2024
- Description illustrations
- Illustrations, tables, graphs, charts
- Description bibliographic
- Includes bibliographical references (pages 44-47).
- Public Abstract (ETD)
Pushing and pulling material handling carts is common throughout many industries and workplace tasks. Employees who frequently push and pull material handling carts experience increased risk of developing a musculoskeletal disorder. Unfortunately, current methods to assess push and pull exposure variables are error prone. We instrumented a material handling cart to be brought into the field to collect data on push and pull exposure variables in a direct, continuous fashion with the following devices: two load cells placed onto the handlebars, one accelerometer, and one rotary encoder underneath the cart. Four hotel banquet employees performed their routine material handling tasks required for event setup while using the instrumented cart. Although nearly all estimates of maximum pushing and pulling forces during cart use were considered low risk, increasing the weight of items in the cart clearly increased pushing/pulling forces, and pushing/pulling on carpet required more force than pushing/pulling on other surfaces. Overall, the project will inform the continued development of methods for directly measuring pushing/pulling forces in field-based settings.
- Academic Unit
- Occupational and Environmental Health
- Record Identifier
- 9984697940202771
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