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The authors ask you:
Drilling into concrete or metal ceilings is a strenuous task that construction workers regularly perform to hang ductwork, piping, and electrical equipment. The task can be associated with risk of falls from ladders and with upper body injuries due to the high forces and awkward postures applied during drilling. Four generations of intervention devices were developed, built, field tested, and modified based on usability, productivity and safety evaluations by 47 commercial construction workers in the field. Testing was done at 28 construction sites while workers performed overhead drilling using their usual method or the intervention devices. Generation 1 devices were rejected due to poor usability and productivity. Generation 2 devices were rated superior on most qualities to usual method. Additional modifications were made in Generation 3 and 4 devices to improve productivity, usability, and reduce musculoskeletal risk. The study demonstrates that multiple rounds of field testing may be necessary to identify health and safety interventions that both reduce musculoskeletal risk and are acceptable to workers.
One of the most physically demanding tasks in construction is overhead drilling into concrete or metal ceilings for the attachment of bolts and anchors to hang pipes, ducts, wiring, and equipment (NIOSH 2002). Overhead drilling is associated with risks of falls from ladders, acute injuries to the wrist when the drill seizes, and chronic wrist, elbow, shoulder, and back musculoskeletal disorders due to the high loads (Figure 1) (Washington State Fund, 2000).
Over the past 3 years we have developed 4 generations of devices for overhead drilling that address these risk factors. The devices have been formally tested by commercial construction workers in the field and each generation has been improved based on worker feedback. The Generation 1 designs were rejected by construction workers due to poor productivity and usability. The Generation 3 design has more favourable ratings across all usability, fatigue, safety, and productivity measures when compared to the usual method.
The question posed to you: Does this device design have applications in other jobs or industrial sectors?
Figure 1. Typical method for overhead drilling while in a scissor lift or on a ladder.
The project was conducted in 3 phases. Each phase involved (1) the development of two or more prototype interventions with input from construction workers; (2) formal field evaluation of the usability, productivity and safety features of the interventions by construction workers performing overhead drilling; and (3) incorporating recommendations from workers into the next generation of device designs. The field evaluation for each generation of devices was done by 14 to 17 commercial construction workers (plumbing, electrical, carpentry, sheet metal trades) while they performed their usual work using either the intervention devices or their usual method. The order of testing was randomized.
Generation 1 devices involved a foot lever actuator or an inverted drill press design to lift a column with a drill set in a saddle on the top of the column. The reach of the drill was 10 feet. Overall, the usual method was preferred to the interventions based on better set-up time and time to move between holes (N=16). However, the usual method was more fatiguing. There was some preference of the inverted drill press design over the foot lever design to prevent leg fatigue.
Figure 2. Generation 1 devices: foot lever design and inverted drill press design.
The Generation 2 devices used the inverted drill press design but included a wheeled base for rapidly moving the device between holes. Three different methods of rapidly setting the column to vertical were evaluated. A vertical column carries the advantage of being able to align on marks on the floor, thereby eliminating the need to mark the ceiling with a ladder. Overall, the collar base method was preferred over the other methods for aligning the column (N=14). The collar base was rated better than the usual method across almost all usability, productivity, safety, and fatigue ratings. However, it was recommended that the device be designed for higher ceilings and that the base is redesigned to make it easier to drill next to stud walls. The device, with a small base, worked well in a scissor lift.
The Generation 3 device used a base with 3 wheels instead of 4. This reduced column rocking and made it easier to drill next to a wall. The device included a double nested column to increase reach to 15 feet. The device is currently being tested in commercial construction sites in Portland, OR. Feedback is very positive (N=17). The primary concern is sustained neck extension during drilling.
Figure 3. Generation 2 collar base (10' reach) and Generation 3 double column (15' reach) device designs. Four different saddles can accommodate different drill designs.
A Generation 4 device is being evaluated to test methods for reducing neck extension. The columns are scored to make it easier to determine when the drilling depth is achieved. A mirror and an inexpensive camera system are being evaluated to determine if they are usable and can decrease neck extension. This testing is occurring in commercial construction sites in Vancouver, BC.
Field testing by experienced construction workers and their feedback on design was vital to the successful development and improvement of the intervention devices. It is difficult to anticipate how interventions will perform without testing them in varied field settings. Designers of health and safety interventions should include an adequate number of rounds of testing and design modifications before settling on a final design.
We are currently looking for construction partners to further evaluate the usability and productivity of the Generation 3 and 4 devices. We are also interested in partnerships with other industries that may find the device design valuable in reducing fall risk or musculoskeletal injuries.
The findings and conclusions in this poster are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Citations to Web sites external to NIOSH do not constitute NIOSH endorsement of the sponsoring organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of these Web sites.
