2010-10-21 01-Worksafe BC Report Feb2010

Focus on TomorrowReseaRch funded by WoRksafebc

An Intervention for Overhead Drilling into ConcreteFebruary 2010

Principal Investigator/ApplicantDr. Stephen Robinovitch

RS2006-OG15

AN INTERVENTION FOR OVERHEAD DRILLING INTO CONCRETE

February 2010

Stephen Robinovitch*†, David Rempel‡, Timothy Chueh†, Anne-Kristina Arnold*, Marcus Yung*

* Department of Biomedical Physiology and Kinesiology, Faculty of Science, Simon Fraser University, Burnaby

† School of Engineering Science, Faculty of Applied Sciences, Simon Fraser University, Burnaby ‡ Division of Occupational and Environmental Medicine, University of California, San Francisco


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Main Messages The construction industry, which employs a significant portion of working British Columbians, exposes workers to risk factors associated with the development of musculoskeletal disorders. Particularly problematic in the neck and shoulders are tasks requiring overhead work. Plumbers, electricians and sheet metal workers who frequently drill overhead to attach anchors for hanging pipes, ducts, conduit, and wiring trays are particularly at risk.

Few intervention devices aimed at reducing these disorders have been developed for commercial use. This study used a participative approach involving workers, contractors and researchers to develop and evaluate an inverted drill press with different attachments to be used in construction. The intervention device supported a hammer drill at the top of a column and the column was advanced up during drilling using a rotary handle and linear gear.

Four drilling methods were compared: the usual method where the worker uses a drill with the hands while standing on a ladder, the intervention device alone, the intervention device with a mirror system, and the intervention device with a camera and display system. Neck and shoulder angles, body fatigue, productivity and subjective ratings of usability were compared between methods.

Our study revealed several important points:

• Fatigue levels in the neck, shoulders, hands and forearms, lower back, and legs were less with all three intervention devices compared to the usual method.

• Awkward shoulder postures were not reduced with the intervention devices but overall risk factors for musculoskeletal disorders were reduced based on lowered force on the joint and less fatigue.

• Neck extension did not worsen when using the intervention device alone compared to the usual method.

• Neck extension and neck fatigue were reduced by using the intervention device with the camera and display system.

• Usability ratings of ease and speed of drilling were better with all intervention devices than the usual drilling method. No usability differences were found between the different configurations of the Inverted Drill Press.

• Setup and accuracy of targeting the next hole were rated better with the usual method than with the intervention devices.

• On average, the intervention devices were somewhat slower compared to the usual method; however, workers reported that the intervention devices performed faster in certain scenarios such as straight lines or worksites with less clutter on the ground and ceiling.

• Performance with the intervention device improves when it is used for more than 20 holes.

The results support the need for stakeholders to encourage the development and on-site use of this type of intervention device. We recommend the use of the overhead drilling device under certain conditions:

• The device should be used when 20 or more overhead holes are being drilled consecutively;

• The device was most successful in “straight run” applications, where the floor is relatively clear, such as underground parking and tunnels;

• The device is slower in renovations or cluttered workplaces, but if many holes are required, the device may still be beneficial;

• The device may be considered as a useful tool in helping workers who are recovering from surgery or injuries in the shoulder and neck, return to work more quickly;

• A training program should be developed outlining the situations that would benefit from the use of the device and proper use procedures.

• While further research and development into IDPs is merited, the device can currently be used in a variety of construction scenarios to reduce fatigue and risk factors for musculoskeletal injuries.


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Executive Summary Musculoskeletal Injury (MSI) to the neck, back, and upper extremity is the leading cause of time-loss injury for workers in the construction sector, representing 18% of compensation costs (WorkSafeBC, 2009). One of the most physically demanding tasks associated with disorders in these body parts is overhead work, and in particular, overhead drilling.

The purpose of this research was to develop and expand on an intervention for overhead drilling (IDP) so that the task can be performed with less shoulder force, reduced awkward shoulder and neck postures, and reduced exposure to falls and dust. The plan for the study was divided into 7 phases:

1. Focus group meetings 2. Design system for overhead drilling 3. Build overhead drilling system 4. Pilot test overhead drilling system 5. Build two robust overhead drilling systems 6. Evaluation Study 7. Disseminate Findings

At the start of this project, the IDP originally developed by Rempel et al. (2007), had reached its 3rd generation and was composed of a locking 3-wheeled base, a telescoping column, and a drill saddle on top of the column. During Phase 1 of our study, we conducted 4 focus groups in order to gain insight into the overhead drilling task as well as elicit feedback on the 3rd generation IDP. The focus groups were composed of 19 participants including electricians, plumbers and pipe fitters, sheet-metal workers, and employers. Results from these sessions informed the design of the 4th generation IDP. Modifications included two interchangeable attachments to aid in visibility of the ceiling while working from the ground. The first was a mirror on an adjustable arm meant to allow a user to look into the mirror while keeping their neck in a neutral posture and giving them a field of view of the ceiling. The second attachment was a camera system that included a display attached to the same adjustable arm as the mirror, and a camera that attached below the drill saddle that provided a constant field of view of the drill and the ceiling above it. Further modifications included:

• a 3-wheeled base with locking hard castors; • a triple-nested design in order to reach higher ceiling heights; • scoring on the column at 1cm and 1inch marks in order to aid in reducing neck extension; • a Hilti TE-6s Hammer Drill was used providing an opportunity to use the vacuum attachment for the drill

as a method to reduce the dust output during drilling.; • a new hinged design for the drill saddle that allowed the drill to be flipped over in order to change bits and

reduce the height of the device; • a depth rod used to create the depth stop distance.

Pilot Study

The pilot study evaluated four methods of overhead drilling: the usual method (standing on a ladder and drilling using a hand held drill), the 4th generation IDP, the device with a camera system (IDPw/C), and the device with a mirror (IDPw/M). The aim was twofold: to test our evaluation methods and refine the intervention design. Seven construction workers (6 male, 1 female) with no prior history of upper limb MSI participated: 4 sheet-metal workers, 2 piping/mechanical workers, and 1 electrician.

The IDPs were found to be less fatiguing than the usual method of drilling. The IDP on its own did not reduce neck extension; however, the IDP with camera and display system (IDPw/C) was more effective in maintaining a neutral neck posture. The camera system was ranked higher in key qualities such as comfort and overall use.


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Based on its positive postural results and higher rankings in key categories, we chose the camera system to be the better solution than the mirror, and selected it for use in the final evaluation study.

On-site experience and feedback from the construction workers gathered during the pilot testing led to further changes to the IDPs in preparation for the full field tests. The changes included:

• Castors replaced with larger pneumatic tires in order to provide better mobility over small debris and higher ground clearance.

• The flexible arm used to support the display was replaced with a more robust adjustable and locking arm. • A new video and power cable management system for the hammer drill, camera, and display.

Evaluation Study

Three drilling methods were evaluated in the field evaluation study: the usual drilling method (standing on a ladder or lift and drilling using a hammer drill held by the hands), using the IDP, and using the IDP with a camera system (IDPw/C). 17 subjects without history of musculoskeletal injuries in the neck or shoulder evaluated the methods. The four drilling conditions were evaluated on three parameters:

1. Ability to reduce awkward postures in the neck and shoulder (measured by inclinometers); 2. Ability to maintain performance (measured by time to complete tasks analyzed from video tape); 3. Subjective measures of fatigue, comfort, productivity and usability (from self-reported questionnaires).

Fatigue

Both of the IDPs produced less rated fatigue in the shoulder, hand, forearm, lower back and the legs more than the usual method of drilling. The IDPw/C also worked as intended and reduced neck fatigue compared to both the usual method and the IDP on its own.

Shoulder and neck posture

The design of the interventions aims to keep the shoulder and neck in neutral postures. Both the IDPs reduced time spent with the shoulder in the least harmful position (0 to 45 degrees) and the most harmful position (more than 90 degrees). More time is spent in a 60 to 90 degree postures (which is also considered problematic) when using the IDPs. Due to the triple-nested column design, 2 cranks are required to fully extend the IDP. The second crank in particular could cause awkward shoulder posture depending on the height of the user. While the display system was designed to be adjustable for user height, the cranks on the device could not be moved. To reduce awkward shoulder posture, future iterations of the device should position the cranks at a lower position.

Neither of the IDPs increased the percent time spent in neck extension compared to the usual method. In fact, the IDPw/C substantially reduced the percent time in neck extension compared to both the IDP on its own, as well as the usual method. We believe continued exposure to the IDPw/C can further reduce awkward neck posture as users get accustomed to taking full advantage of the camera and display.

Usability

Perception of usability of the device is critical to its acceptance on the construction site. A few qualities were found to be better with the usual method compared to either of the IDPs including: ease of setting up, accuracy when targeting the next hole, ease of making adjustments and speed of making adjustments. These qualities are all related to the tasks of setting up and moving to the next hole.

Importantly, workers found it easier and quicker to know when they had reached the desired drill depth with both the IDPs. There are a variety of ways trades people gauge depth when drilling holes including wrapping electrical tape around the drill bit, or using a marker to mark the depth on the drill bit. Both techniques require looking at the drilling site and focusing on when the mark or the tape has become flush with the ceiling. This causes added neck extension and dust exposure with the person looking directly at the drilling site. With the IDP, the desired depth is


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set with the depth rod on the saddle. Knowing when drilling was complete became a simple matter of feeling when the drill could no longer progress and did not require a visual check.

The IDPs outperformed the usual method in key categories of interest: drilling ease, drilling accuracy and drilling speed.

Performance

Productivity is important on a construction site. Although an intervention may impact injuries, discomfort and usability, it is unlikely that the intervention will be used if it significantly slows down the production on site. We can conclude from the results that both the IDPs took longer to drill a hole compared to the usual method of overhead drilling. The reason for the increased time was due to longer targeting and longer approach times. No differences were found between methods in the drilling and departure times.

The longer targeting time reveals that users took longer to move from one hole to the next with the IDPs compared to a worker moving a ladder and a drill. From observations, this is particularly true for construction sites with debris on the ground. Even when carrying a ladder, it is much quicker to step over a small pile of debris than it is to navigate the IDPs over or around it. Also, when arriving at the next hole to be drilled, subjects spent more time positioning the IDPs so that they lined up directly below the target before they began their approach. Compared to positioning a ladder with the usual method, less care was needed to line the ladder up directly below the hole because positioning the drill to the target was done by hand at the top of the ladder during the approach.

When approaching the target (start to climb the ladder or begin to raise the column), the IDPs were also slower than conventional overhead drilling. This was the result of 2 primary factors. First, climbing up a ladder to reach the ceiling took less time than cranking the IDPs to a ceiling of the same height. This factor is sometimes negated when the user does not have to completely lower the IDP when moving to the next hole. This is often the case when the ceilings are clear or if there are not many other utilities already hung. The second factor is the time it takes to position the drilling bit against the ceiling at the target location. With the usual method, the worker is in close proximity to the ceiling and is positioning the drill directly with their hands which allows them to position the drill quickly and accurately. With the IDP, the worker is further from the ceiling by virtue of working from the ground, and is positioning the drill through the IDP which adds a level of complexity.

Several factors should be considered in assessing performance. Firstly, subjects had over an average of 5 years experience and were all very comfortable with the overhead drilling task. Conversely, few subjects had the opportunity to spend more than a morning or afternoon with the IDP. Based on this, and the possible learning curve of using a new tool, workers may be able to learn to use the IDPs faster over time. This finding was confirmed in a prior study where productivity improved during the first 20 holes but was level after that.

Secondly, the fatigue, postural, and usability benefits of the IDPs may also factor in when looking at performance long term. During this study, we required subjects to drill a minimum of 4 holes. The IDP could gain a performance advantage over the long run when drilling many holes because fewer and shorter breaks are needed due to reduced fatigue and increased comfort.

Lastly, workers described scenarios where the IDP would be particularly useful such as straight runs or “cleaner” job sites. The results from our analysis allow us to focus our attention on improving the performance of targeting and the approach during future research and development of the IDP.

CONCLUSIONS

The results from this study demonstrate that the use of the intervention device with a camera system can reduce the risk of neck and shoulder injuries and discomfort associated with overhead drilling for electricians, plumbers and sheet metal workers drilling overhead into concrete. Our results showed however, that there is a learning period with the device during which productivity is slower than acceptable. This appears to be short (about 20 holes), but may be an impediment to a tradesperson who uses the device infrequently. We can recommend the use of the overhead drilling device under certain conditions:


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• The device should be used when 20 or more overhead holes are being drilled consecutively;

• The device was most successful in “straight run” applications, where the floor is relatively clear, such as underground parking and tunnels;

• The device is slower in renovations or cluttered workplaces, but if many holes are required, the device may still be beneficial;

• The device may be considered as a useful tool in helping workers who are recovering from surgery or injuries in the shoulder and neck, return to work more quickly;

• A training program should be developed outlining the situations that would benefit from the use of the device and proper use procedures.

Anecdotal evidence from construction workers and employers indicates that the device (possibly with other attachments) may be useful in other overhead work applications within the construction industry (such as setting anchors). Furthermore, there are likely applications for a similar type of device in other industries doing overhead work. To maximize its applicability, future research should focus on modifying the IDP characteristics and method of use to reduce the time required for targeting and approach to the drill site.


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Table of Contents Main Messages ............................................................................................................................................. i

Executive Summary ..................................................................................................................................... ii

Table of Contents ........................................................................................................................................ vi

1. Research Problem................................................................................................................................1

1.1. Musculoskeletal Injuries in Overhead Work ................................................................................1

1.2. Other Health and Safety Risks....................................................................................................1

2. Methodology.........................................................................................................................................1

2.1. Development of the Inverted Drill Press .....................................................................................2

2.2. Pilot Test .....................................................................................................................................2

2.2.1. Contrasting mirror and camera systems ............................................................................................ 3

2.2.2. Overview of changes made to the IDP ............................................................................................... 3

2.3. Evaluation Study Subjects and Locations ...................................................................................3

2.4. Evaluation Study Protocol ...........................................................................................................4

2.5. Evaluation Study Outcome Measures.........................................................................................4

2.5.1. Inclinometers...................................................................................................................................... 4

2.5.2. Digital Video ....................................................................................................................................... 4

2.5.3. Questionnaires ................................................................................................................................... 4

2.6. Data Analysis ..............................................................................................................................5

3. Research Findings ...............................................................................................................................5

3.1. Fatigue ........................................................................................................................................5

3.2. Posture........................................................................................................................................6

3.2.1. Shoulder Flexion and Abduction ........................................................................................................ 6

3.2.2. Neck Flexion and Extension................................................................................................................ 7

3.3. Usability.......................................................................................................................................8

3.4. Performance................................................................................................................................9

4. Implication for Future Research on Occupational Health ...................................................................11


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4.1. Future Research .......................................................................................................................11

4.2. Future Development .................................................................................................................12

5. Policy and Prevention.........................................................................................................................12

5.1. Prevention Implications .............................................................................................................12

5.2. Relevant user groups ................................................................................................................12

5.3. Policy-related interactions undertaken......................................................................................13

6. Dissemination.....................................................................................................................................13

6.1. Professional Audiences ............................................................................................................13

6.2. Scientific Audiences ..................................................................................................................14

7. Acknowledgements ............................................................................................................................15

8. References .........................................................................................................................................16

Appendix A .................................................................................................................................................18

Appendix B .................................................................................................................................................25


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- FINAL REPORT -

1. Research Problem 1.1. Musculoskeletal Injuries in Overhead Work Musculoskeletal Injury (MSI) to the neck, back, and upper extremity is the leading cause of time-loss injury for workers in the construction sector, representing 18% of all compensation costs (WorkSafeBC, 2009). One of the most physically demanding tasks associated with these disorders is overhead work, and in particular, overhead drilling.

Overhead drilling into concrete to attach anchors into the ceiling in order to hang pipes, ducts, conduit, and wiring trays is a strenuous task frequently performed by construction trades. Workers from electrical (Hunting et al., 1994), plumbing (Hildebrandt, 1995), and sheet-metal (Welch et al., 1995) trades experience high musculoskeletal loads in the upper limbs, neck, back, shoulders, and knees when drilling holes into ceilings (Albers et al., 2005). In these trades more than 66.7% perform overhead work at least 10 hours/week. According to Rosencrance et al. (1996), 41% of sample construction workers complain of work-related shoulder pain associated with overhead work.

Shoulder muscle load is a function of the amount of elevation of the upper arm, and the load (e.g., weight of the tool) held in the hand (Sigholm, 1984). With the arm held horizontally (90 degrees of shoulder flexion or abduction), the weight of the arm alone is enough to induce significant fatigue in 5 minutes (Hagberg, 1981). Shoulder elevation between 60 to 120°, observed while working overhead may lead to degeneration of the rotator cuff tendons (Flatow et al., 1994). Increasing hours of overhead work is also strongly associated with shoulder pain and disorders of the shoulder rotator cuff and the biceps muscles (Hagberg 1981; Olson 1987; Holmstrom 1995). Sandmark et al. (1994) found that sustained neck extension with hands above shoulder height led to increased neck muscle loads and increased neck pain.

1.2. Other Health and Safety Risks While the risk of MSI caused by overhead work justifies the need for an intervention, there are other safety concerns with overhead drilling. Falls from an elevation are the second most common accident claim made by construction workers over the past 5 years (WorkSafeBC, 2009). Over shoulder work can lead to increased body sway and increased upper extremity fatigue resulting in decreased whole-body postural stability (Nussbaum 2003). This may increase the risk of falls on construction sites, and is of particular concern in the target population of workers, who are often working at height using ladders, scaffolding, and scissor lifts. In addition to falls, overhead drilling also exposes workers to concrete dust, noise, and vibration.

Although there is clearly a need for an overhead drilling intervention, devices to decrease the risk of shoulder abduction and flexion and load associated with overhead drilling are not widely used and have not been systematically evaluated (Lindberg, 1991). The intervention device developed for this study aims to address the key issue of MSI while considering other health and safety risks.

2. Methodology The purpose of this research was to develop and expand on an intervention for overhead drilling so that the task can be performed with less shoulder force , reduced awkward shoulder and neck postures, and reduced exposure to falls and dust. The study was divided into 7 phases:

1. Focus group meetings 2. Design system for overhead drilling 3. Build overhead drilling system 4. Pilot test overhead drilling system 5. Build two robust overhead drilling systems 6. Evaluation study 7. Disseminate findings


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- FINAL REPORT -

2.1. Development of the Inverted Drill Press The inverted drill press (IDP) is a device first developed by co-investigator David Rempel et al. based on rudimentary devices found in the field to assist in overhead drilling. At that start of this project, the IDP had reached its 3rd generation and was composed of a locking 3 wheeled base, a telescoping column, and a drill saddle that sits on top of the column. Figure 1 is a photograph of the IDP used in this study.

Figure 1: Inverted Drill Press

During Phase 1 of our study, we conducted 4 focus groups in order to gain insight into the overhead drilling task as well as elicit feedback based on the 3rd generation IDP. The focus groups were composed of 19 participants including electricians, plumbers and pipe fitters, sheet-metal workers, and employers. After meeting with the trades people, we began Phase 3 of our study and designed a 4th generation IDP based on feedback received during the focus groups.

One of the key concerns that arose from observations made on the 3rd generation IDP was the increase in neck extension due to working on the ground. Targeting marks on the ceiling was also more difficult from the ground. Based on these concerns, the 4th generation IDP included two interchangeable attachments to aid in visibility of the ceiling while working from the ground. The first was a mirror on an adjustable arm meant to allow a user to look into the mirror while keeping their neck in a neutral posture and giving them a field of view of the ceiling. The second attachment was a camera system that included a display attached to the same adjustable arm as the mirror, and a camera that attached below the drill saddle that provides a constant field of view of the drill and the ceiling above it.

The base for the 4th Generation IDP was 3-wheeled and used locking hard castors. The column featured a triple-nested design in order to reach higher ceiling heights. Sitting on the wheeled base, the tip of a standard 1/2” drill bit was 246cm above the ground when the column was fully lowered and reached 477cm full extended. The centre of the two cranks for the column stood at 145cm and 171cm from the ground. The column was scored with 1cm and 1inch marks so that drilling progress was easier to monitor in order to aid in reducing neck extension.

For the 4th Generation IDP, a Hilti TE-6s Hammer Drill was used exclusively based on its widespread use in the field. This provided an opportunity to use the vacuum attachment for the drill as a method to reduce the dust output during drilling. The saddle that the drill sat in employed a new hinged design that allowed the drill to be flipped over in order to change bits and reduce the height of the device. The saddle was also fitted with a depth rod used to create the depth stop distance. Once set, the depth rod would hit the ceiling and prevent the IDP from progressing when the desired drill depth was reached. The design changes to the IDP were then built during Phase 3 of the project and prepared for pilot testing in Phase 4.

2.2. Pilot Test The pilot study evaluated the biomechanical demands and usability of four methods of overhead drilling: the usual method (standing on a ladder and drilling using a hand held drill), an intervention device (IDP), the device with a camera system (IDPw/C), and the device with a mirror (IDPw/M). Seven construction workers (6 male, 1 female) with no prior history of upper limb MSI participated: 4 sheet-metal workers, 2 piping/mechanical workers, and 1 electrician.

The studies were conducted at 4 worksites. An inclinometer with data logger was used to measure neck angles. Work tasks were videotaped to capture productivity. After using each method, subjects completed a questionnaire that rated drilling parameters and body fatigue levels using a 6-point (0-5) Likert scale. Improvements to the device, safety issues and user opinions were elicited using open-ended questions.


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- FINAL REPORT -

Repeated measures ANOVA was used to examine the differences in rated body fatigue and usability between drilling method. Postural analysis from the inclinometers was synced to the recorded video divided into 4 subtasks: targeting, approach, drilling, and departure. Mean neck angles and percent of time in 10° angle bins for each hole drilled were compared for each method within all subtasks. Time to complete subtasks was also recorded.

Perceived neck fatigue results suggested improvement when any of the intervention devices was used in comparison to the usual method. However, the postural data showed that the intervention device on its own was associated with the same amount of neck extension as the usual method for all subjects. This finding justified the need evaluate the effect of a mirror or camera system on reducing neck extension with the device.

The intervention devices were favored over the usual method in speed of drilling however performance data showed that overall speed of drilling appeared to be faster with the usual method. Intervention devices were also given better ratings in perceived drilling stability; however subjects preferred the usual method for drilling accuracy. Subjects found “overall ease”, which encompasses all aspects of drilling, to be significantly better with all configurations of the intervention device than the usual method.

2.2.1. Contrasting mirror and camera systems No significant differences were found for the neck or shoulder fatigue ratings between the mirror and the camera system. Neck angle frequency suggested that the camera was more effective in maintaining a neutral neck posture compared to the mirror.

Usability ratings and task time measures for the mirror and camera system showed no significant differences. The camera system was ranked significantly higher than the mirror for comfort, a key criterion in our evaluation of the two configurations. The camera system was also ranked higher overall. The mirror was ranked significantly higher than the camera system for stability, durability, and storage. These issues were weighted less than comfort in our comparison since both issues are heavily influenced by the prototype nature of the device and camera system. Based on its positive postural results and higher rankings in key categories, we chose the camera system to be the better solution and it was used in the next tests.

2.2.2. Overview of changes made to the IDP On site experience and feedback from the construction workers gathered during the pilot testing led to several changes to the inverted drill press in preparation for the full field tests. The changes included:

• Castors replaced with larger pneumatic tires in order to provide better mobility over small debris and higher ground clearance.

• The flexible arm used to support the display was replaced with a more robust adjustable and locking arm.

• A new video and power cable management system for the hammer drill, camera, and display.

Figure 2 shows the inverted drill press with camera and display system as it was for the field tests.

Figure 2: Inverted Drill Press with Display

2.3. Evaluation Study Subjects and Locations Trade unions and construction associations were informed and supportive of the project. Recruitment began with contacting general contractors for specific job sites. After gaining permission and support from general contractors, sub-contractors for specific trades would be contacted to participate. When sub-contractors were ready to participate, field tests occurred on days when our required minimum amount of overhead drilling was needed for their day’s tasks.


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- FINAL REPORT -

Field tests ran from April 2008 through January 2009 across Metro Vancouver. Sixteen construction workers participated in this study. Nine were pipefitters and plumbers, 5 were electricians and 2 were sheet metal workers. Subjects had no prior history of upper limb musculoskeletal injuries and performed overhead drilling on a regular basis. All subjects were male and between 19 and 51 years of age ( = 28.9 ± 8.7 years). All but one participant were right hand dominant and had a mean 5.4 ± 6.9 years of experience in the trade. The mean subject height was 179.4 ± 7.4 cm and mean weight was 83.4 ± 14.7 kg. All subjects gave their written consent to participate in this pilot study and all study procedures were approved by the Office of Research Ethics of Simon Fraser University.

2.4. Evaluation Study Protocol Three drilling methods were evaluated in the field: the usual drilling method (standing on a ladder or lift and drilling using a hammer drill held by the hands), using the IDP, and using the IDP with a camera system (IDPC/C). The order of evaluation was randomized. The task of drilling a hole was divided into 4 subtasks: Targeting, Approach, Drilling, and Departure. Definitions for these subtasks for conventional drilling and the drilling with the IDP are given in Appendix A.

An equal number of holes were drilled using each method. The total number of holes varied between subjects depending on the number of holes they were required to drill for their work that day. We required a minimum of 4 holes for each drilling method in order for the subject to participate in the study. Participants were given practice time with each drilling method, prior to data collection, to reduce error due to learning effects. All 3 drilling methods were observed on the same work day.

2.5. Evaluation Study Outcome Measures Inclinometers, questionnaires, and video recordings were used to gather data for the study. The following sections describe their purpose and methods used.

2.5.1. Inclinometers Neck posture (extension/flexion) and shoulder posture (abduction and flexion) for the dominant arm were measured using inclinometers. Three inclinometers with built in data loggers (MicroStrain, Inc. Virtual Corset) were used. One inclinometer was attached to a hard hat. The other two inclinometers were placed perpendicular to one another in a custom enclosure and strapped to the upper arm of subjects. The inclinometers continuously sampled data at 15 Hz. The reference position (0° neck flexion/extension, 0° shoulder abduction and flexion) was recorded when the participant was standing upright, hands at their sides, while looking straight ahead. Collected data was downloaded to a computer after completing the field test with each subject. Data markers were set using a button on the inclinometers at the start and end of each drilling method. Positive angles in the neck were assigned to extension and negative angles were assigned to flexion. Shoulder flexion and abduction were recorded as positive angles in the two shoulder inclinometers.

2.5.2. Digital Video Work tasks during all three methods were videotaped using a Canon Optura Xi Digital Video Camcorder. Captured video was downloaded to an off-site computer. Measures from the video were gathered using CAPTIV (TEA, France), a video analysis software designed to synchronize video with visual observations (post coding) and measurements from sensors. Inclinometer data was manual synchronized to the video using the data markers set at the start and end of each drilling method and the video recording of the actual button presses. Task and sub-task duration measures were gathered using the post coded video. Posture measures were also isolated to match up with actual performance of the tasks.

2.5.3. Questionnaires After subjects completed drilling holes with a method, they completed a questionnaire which rated drilling parameters and body fatigue levels. Drilling parameters and fatigue were scored using a 6 point (0-5) Likert scale. Improvements to the device, safety issues and user opinions were elicited using open-ended questions.


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- FINAL REPORT -

After completing all three drilling methods, a questionnaire ranking the three drilling methods from best to worst on a variety of factors was administered. See Appendix B.

2.6. Data Analysis Posture data was analyzed by comparing collected data to ergonomic guidelines for safe postures in the neck and shoulder (McAttamney and Corlett, 1993; Persson and Kilbom, 1983). McAttamney and Corlett’s RULA divided shoulder angle into 0-20, 20-45, 45-90, and 90+ bins while Persson and Kilbom’s VIRA divided angles into 0-30, 30-60, 60-90, and 90+ bins. We adopted a hybrid division with angular bins for shoulder elevation divided into 0-45, 45-60, 60-90, and 90+ degrees. Both the RULA and VIRA consider neck flexion > 20° or any neck extension > 0° problematic. As the concern with overhead work is primarily with neck extension, neck posture was divided into extension (> 0 degrees) and flexion (< 0 degrees) for analysis. Our posture analysis calculated percent time joints angles were in these ranges.

Ratings results from the questionnaires on usability and fatigue was analyzed using the Friedman test. A pair-wise Wilcoxon signed-rank test was used as a post-hoc test when the Friedman tests showed significant results (p < 0.05). Posture and performance data was analyzed using repeated measures ANOVA with a paired sample t-test used as a post-hoc test when the ANOVA showed significant results.

3. Research Findings 3.1. Fatigue Subjects rated their level of fatigue (tiredness) after drilling the required number of holes per method. The ratings were made on a 6-level scale from 0 to 5, where 0 represented no fatigue and 5 represented very fatigued. The results are given in Figure 3 and in Table 2 in Appendix A.

Figure 3: Mean Fatigue Ratings (Lower is better)

It is important to note that the prevalence of fatigue ratings above 0 for the usual method even after drilling only 4 holes supports the need for an intervention. Users only reported no fatigue in 19% of ratings for the usual method. Combined, users reported feeling no fatigue in 65% of all ratings for the IDP and IDPw/C.

0 1 2 3 4 5

Neck

Shoulder

Hand and Forearm

Lower Back

Leg

Usual Method

Inverted Drill Press

Inverted Drill Press w/ Camera


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- FINAL REPORT -

Results from the Friedman test and the Wilcoxon post hoc are given in Table 3. Only significant results from the post hoc are reported.

Significant differences in perceived fatigue were found in all body segments of interest. Results showed that both the IDP and IDPw/C significantly reduced fatigue in the shoulder, hand and forearm, lower back, and legs compared to the usual drilling method. No reduction in neck fatigue was found between the usual method and the IDP. While it is satisfactory that the IDP did not increase neck fatigue, the need to reduce neck fatigue is still evident with the IDP on its own.

The camera and display system was introduced to the IDP with the goal of reducing awkward neck postures and reducing neck fatigue when using the IDP. The results show that the IDPw/C significantly reduced perceived neck fatigue compared to both the usual method and the IDP on its own. Other than neck fatigue, no differences were found between the IDP and the IDPw/C. This result was expected since the camera and display system did not affect any aspect of drilling beyond providing an alternate place to look while performing the task.

Results from the fatigue ratings showed that the IDP configurations reduced fatigue in the shoulder, hand and forearm, lower back and the legs. The IDPw/C also worked as intended and reduced neck fatigue compared to both the usual method and the IDP on its own. The next section presents the postural data in order to determine if the fatigue levels correlated with the neck and shoulder postural changes.

3.2. Posture Postural data was recorded for the neck and the shoulder of the dominant arm of the test subjects using inclinometers. A summary and analysis of the results are presented in the following sections.

3.2.1. Shoulder Flexion and Abduction By removing the drill from the hand the IDP decreases the direct load of the drill and the force required to drill on the arm and shoulder. This is a critical advantage of the IDP. However, an additional concern was whether the postural loading on the shoulder was affected by using the interventions. Table 4 in Appendix A presents the mean percent time spent in each angular range for the three drilling methods tested. The final column presents the results from the repeated measures ANOVA analysis and the post hoc t-test. Figure 4 presents the mean values.

Figure 4: Shoulder Posture (Mean Percent Times)

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Usual Method Inverted Drill Press Inverted Drill Press w/ Camera

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Differences were found in the 0 to 45 degree bin and the 60 to 90 degree bin between the usual method and the IDPs. All the differences found between the Usual Method and the IDP were also found with the IDPw/C. The posture results reveal that the camera and display system do not affect shoulder posture when using the device IDP and as such, the following discussion refers to both devices as the IDPs.

The IDPs reduced time spent with the shoulder from 0-45 degrees and increased time spent with the shoulder between 60 to 90 degrees. The results indicated that the IDPs did not reduce awkward shoulder postures. However, based on the results from our fatigue analysis the IDPs still reduced the overall musculoskeletal load on the shoulder during the drilling task. This can be attributed to the reduced load on the shoulder joint during drilling when using the IDPs as well as the opinions given by subjects during field tests that drilling with the IDPs was “easier”.

One of the main reasons for the increase in shoulder flexion when using the IDPs was the position of the cranks. Due to the triple-nested column design, 2 cranks are required to fully extend the IDP. The height of the two cranks stood at 145cm and 171cm from the ground. The second crank in particular could cause awkward shoulder posture depending on the height of the user. While the display system was designed to be adjustable for user height, the cranks on the device could not be moved. To reduce awkward shoulder posture, future iterations of the device should position the cranks at a lower position.

3.2.2. Neck Flexion and Extension One of the key concerns of this study was whether or not the IDP increased awkward neck postures, and whether our modified IDP with a camera and display system could reduce that awkward neck posture. Any neck posture above the neutral position is considered a risk factor for MSI (McAttanmey, 1993). Table 5 in Appendix A presents the mean percent time workers spent with their neck in an extended posture using each of the different drilling methods. The final column shows the results from the repeated measures ANOVA analysis and the pos-hoc t-test. Summary data is also shown in Figure 5.

Figure 5: Neck Extension (Mean Percent Times)

The first interesting result from the neck posture analysis was the fact that using the IDP did not increase the percent time spent in neck extension compared to the usual method. This corroborates the fatigue rating results, where users found no difference in neck fatigue when comparing the IDP with the usual method.

The second key result is also in agreement with the results from our fatigue analysis. The IDPw/C substantially reduced percent time in neck extension compared to both the IDP on its own as well as the

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usual method. We believe continued exposure to the new tool can further reduce awkward neck posture as users get accustomed to taking full advantage of the camera and display.

Use of the IDPw/C and to a lesser extent, the IDP on its own, creates bi modal neck posture. Users spend time either looking up directly at the ceiling, or looking forward at the display and resting their neck. Based on observations during the study, increased exposure to the device allows users to increase time spent looking at the display rather than the ceiling.

3.3. Usability Usability and general qualities were evaluated through the questionnaire using a 5-level scale from 1-5. 1 being the most positive (e.g. Very Easy, Very Good) and 5 being the most negative (e.g. Very Difficult, Very Bad). Mean ratings are given in Table 6.

The statistical analysis performed was similar to the fatigue ratings. Results from the Friedman test are given in Table 7. Table 8 presents results from the pair-wise Wilcoxon post hoc for significant results from the Friedman test. Only significant results from the post hoc are reported in Figure 4.

Figure 6: Significantly Different Usability Ratings

No significant differences in usability were found in 12 out of 21 categories. Although this means the IDP did not make improvements in those categories compared to the usual method, it also means that the IDP did not reduce usability in those categories. In designing an intervention for adoption, the intervention must create the desired improvements and benefits without creating a negative impact on other aspects of a task. Any negative impacts must be minimal, or justifiably outweighed by the benefits the intervention device creates. Thus, we consider the lack of significant differences in 12 of the categories as a positive result.

1 2 3 4 5

Knowing when the drilling is complete: Speed

Knowing when the drilling is complete: Ease

Drilling: Speed

Drilling: Ease

Making Adjustments: Speed

Making Adjustments: Ease

Moving to the next hole: Control

Moving to the next hole: Accuracy

SeZng Up: Ease

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In all the categories where a difference was found, no differences were found between the IDP and the IDPw/C. This shows that the camera and display system was able to reduce awkward neck posture without reducing the overall usability of the IDP.

All differences in usability categories found in the questionnaire were found between the usual method and both the IDP and IDPw/C. As such, any reference made to the IDP in this section includes both the IDP and IDPw/C.

Ease of setting up was found to be better with the usual method compared to the IDP. This was an expected result because the IDP is a more elaborate tool than a hammer drill and ladder. With many interventions, it is often the case that while the setup may more complex, the benefits of using the intervention over the conventional method outweigh the inconvenience of a more complicated setup. An example of this in construction would be the use of a lift rather than a folding ladder.

Accuracy when targeting the next hole was found to be better with the usual drilling method compared to the IDP. The distance between the worker and the ceiling is the likely cause of reduced accuracy. Even with the camera and display system, the view provided is still far from the ceiling until the worker begins to elevate the column. While targeting accuracy is important, no difference was found between methods when it came to the accuracy in drilling and thus, the reduced accuracy in moving to the next hole did not affect the accuracy of the end result.. With regards to control when moving to the next hole, the post hoc test revealed no significant differences between any pair of methods.

The ease and speed of making adjustments were both found to be better with the usual method. This was also an expected result because the IDP was a new tool that the subjects had never used before. Also, the more complex a tool, the more complicated its use may be. Consider the ease and speed in making adjusts, such as changing nail size, between a hammer and a nail gun. As long as the intervention provides added benefits elsewhere and overall performance meets requirements, poorer performance in the ease and speed of making adjustments can be negligible. Ease and speed for making adjustments can also improve over time with increased exposure to a new intervention.

The IDP outperformed the usual method in key categories of interest: Drilling ease, and drilling speed. Subjects found the actual task of drilling into concrete easier with the IDP. Although this does not reflect the specific quantitative goals for the intervention device, it is the one key subjective result that suggests the intervention device is doing what it was designed to do. Also important is that subjects felt the IDP was faster in drilling holes than the usual method. This is important, because while subjectively we want the IDP to make drilling holes easier, it must do so without reducing the speed at which holes can be drilled. Quantitative numbers are compared in the Section 3.4 but it is noted that the perception of speed can prove to be just as important in the adoption of a new intervention.

As part of the overall ease in the drill task, subjects found it easier and quicker to know when they have reached the desired depth with the IDP. There are a variety of ways trades people have devised to gauge depth when drilling holes. Techniques include wrapping electrical tape around the drill bit at the desired depth, or using a marker to mark the depth on the drill bit. Both common techniques require the person drilling to look at the drilling site and focus on when the mark or the tape on the drill bit has become flush with the ceiling. This causes added dust exposure with the person looking directly at the drilling site and can also slow down drilling since slowing or stopping the drill temporarily reduces the dust being expelled while the person checks on the drill bit. With the IDP, the desired depth is set with the depth rod on the saddle. Knowing when drilling was complete became a simple matter of feeling when the drill could no longer progress.

The subjective usability results showed that for the most part, the IDP did not significantly change many factors in overhead drilling. Although some factors were found to be poorer with the IDP, the key factor of ease and speed of drilling were found to be better with the IDP.

3.4. Performance


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Performance of the intervention device is key to its adoption in the construction industry. The bottom line in industry is that improved tools, techniques, and workflows in construction will not be adopted unless overall performance is improved or unhindered. Figure 7 summarizes the performance results and these data are presented and analyzed in more detail in Table 9 in Appendix A. Mean subtask times were calculated for each subject and Repeated Measures ANOVA was used to compare subtask times between drilling methods. Paired sample T-Tests were used as a post hoc test when significant differences were found. Only significant results from the post hoc test are reported. The overall completion time is the average time it took to complete one hole and not necessarily the sum of the 4 subtasks because not all subtasks are performed for each hole drilled. For example, a worker can climb a ladder (Approach) and drill (Drilling) more than one hole from the top of the ladder before descending (Departure) and moving the ladder (Targeting). Definitions of subtasks can be found in Table 1.

Figure 7: Mean Task Times by Method

There were no differences found between the IDP and the IDPw/C. We can conclude from this result that the camera and display system neither hindered nor improved the speed at which workers were able to use the IDP. Comparing the IDPs to the usual method, we found that overall, the IDPs took longer to drill a hole compared to usual overhead drilling. The reason for the increased time was due to longer targeting and longer approach times. No differences were found between methods in the drilling and departure times.

The longer targeting time reveals that users took longer to move from one hole to the next with the IDPs compared to a worker moving a ladder and a drill. From observations, this is particularly true for construction sites with debris on the ground, which tends to be the majority of sites. Even when carrying a ladder, it is much quicker to step over a small pile of debris than it is to navigate the IDPs over or around it. Also, when arriving at the next hole to be drilled, subjects spent more time positioning the IDPs so that they lined up directly below the target before they began their approach. Compared to positioning a ladder with the usual method, less care was needed to line the ladder up directly below the hole because positioning the drill to the target was done by hand at the top of the ladder during the approach.

When approaching the target (start to climb the ladder or begin to raise the column), the IDPs were also slower than conventional overhead drilling. This was the result of 2 primary factors. First, climbing up a ladder to reach the ceiling took less time than cranking the IDPs to a ceiling of the same height. This factor is sometimes negated when the user does not have to completely lower the IDP when moving to

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the next hole. This is often the case when the ceilings are clear or if there are not many other utilities already hung. The second factor is the time it takes to position the drilling bit against the ceiling at the target location. With the usual method, the worker is in close proximity to the ceiling and is positioning the drill directly from their hands which allows them to position the drill quickly and accurately. With the IDP, the worker is further from the ceiling by virtue of working from the ground, and is positioning the drill through the IDP which adds a level of complexity.

Several conclusions can be made from the performance numbers. One factor that should be considered is that the subjects had over an average of 5 years experience in their trade and they were all very comfortable with the overhead drilling task. Conversely, we tested subjects on the first day they were introduced to the IDP, and few subjects had the opportunity to spend more than a morning or afternoon with the device. Based on this, and the possible learning curve of using a new tool, workers may be able to learn to use the IDPs faster over time. This finding was confirmed in a prior study where productivity improved during the first 20 holes but was level after that.

The fatigue, postural, and usability benefits of the IDPs may also factor in when looking at performance long term. During this study, we required subjects drill a minimum of 4 holes. Based on the fatigue and comfort benefits of the IDP described in the previous sections, the IDP could gain a performance advantage over the long run when drilling many holes because fewer and shorter breaks are needed due to fatigue and comfort.

Based on feedback from subjects, the performance of the IDP is acceptable as is but there is still room for improvement. Subjects also described scenarios where the IDP would be particularly useful such as straight runs or “cleaner” job sites. The results from our performance analysis allow us to focus our attention on improving the performance of targeting and the approach during future research and development of the IDP.

There are also design improvement that may make improve the productivity of the IDP (e.g., lighter device without a wheeled base that can be carried from hole to hole).

4. Implication for Future Research on Occupational Health 4.1. Future Research The results from this study demonstrate that the use of the intervention device with a camera system can reduce the risk of neck and shoulder injuries and discomfort associated with overhead drilling for electricians, plumbers and sheet metal workers drilling overhead into concrete. Our results showed however, that there is a learning period with the device during which productivity is slower than acceptable. This appears to be short (about 20 holes), but may be an impediment to a tradesperson who uses the device infrequently. Future research could address this concern by assessing the effectiveness of other design features (such as an augmented scoring system on the column, improved targeting and setup methods) and training materials aimed at teaching construction workers how to use the device optimally.

It may be that there are other methods of reducing neck extension with the overhead drilling device that should be evaluated in future studies. Future research may involve the development of a lighter weight column to support the drill that can be easily used in a scissor lift. Research could also address design features which support other tasks involved in the process of drilling overhead that require neck extension such as setting anchors.

There are research opportunities related to addressing other tasks within construction and in other workplaces. It has been suggested that a device for supporting a heavier rock drill (8 to 20 kg) that is used for drilling 1" diameter holes in concrete on highway and bridge retrofitting should be developed. Such a device will likely reduce musculoskeletal risk and hand vibration exposure. A review of application areas would help to identify target industries.


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4.2. Future Development There is interest in developing the device further. Design features for secondary tasks such as carrying and storing need to be refined before the device is marketable. We are currently working with two tool manufacturers (DeWALT and Milwaukee Tool) to determine their interest in taking the device to market. There is some hesitancy on their part, in the current down market, to develop such a new device. In the mean time, we will work with a local machine shop to make the device available to interested contractors.

Future iterations of the inverted drill press should also include design changes based on the results and experience from this study. The base height of the device should be lowered to 7’6” to allow it to operate and low ceiling situations. The location of the cranks should also be lowered to reduce shoulder elevation while cranking.

5. Policy and Prevention 5.1. Prevention Implications This research has clearly shown that it is possible to reduce awkward neck and shoulder postures amongst construction workers drilling overhead. Significant improvements in neck and shoulder postures and discomfort were found with each of the intervention designs over the usual method of drilling. Using the intervention device with the camera showed the best improvement overall. The intervention device had a negative impact on productivity, particularly for setup and moving to the next hole. This increased time may be an impediment to using the device, particularly for situations where there are few holes to drill and the floor is cluttered. With extended use of the device, it is anticipated that further gains in productivity will be seen.

Based on our findings, we can recommend the use of the overhead drilling device for overhead drilling into concrete ceilings under certain conditions:

• The device should be available in situations where 20 or more holes are being drilled consecutively;

• The device was found to be most successful in “straight run” applications, where the floor is relatively cleared of debris so that the device can be wheeled from hole to hole, most notably parkades and tunnels;

• The device is slower in renovations or cluttered workplaces, but if a number of holes are required, the device will still be beneficial;

• The device should be considered as a useful tool in helping workers with musculoskeletal injuries or recovering from surgery in the shoulder and neck return to work more quickly;

• A training program should be developed outlining the benefits of use of the device and proper use procedures;

• A 1 page flyer which illustrates the above points should be distributed to all construction contractors and union halls;

• Construction equipment suppliers and rental facilities should be encouraged to stock and supply the devices to reduce cost to contractors.

5.2. Relevant user groups Our research is relevant to three distinct user groups: construction workers and contractors, construction equipment manufacturers and health and safety researchers.

Our research focused on specific trade workers within the construction industry who had reported high levels of neck and shoulder discomfort in previous studies: electricians, plumbers and sheet metal workers performing overhead drilling into concrete. Our study showed that the intervention device with the


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camera has the potential to reduce musculoskeletal discomfort and injury in the shoulder and neck for these specific workers. Although other workers and tasks were not investigated, anecdotal evidence from construction workers and employers indicates that the device (possibly with other attachments) may be useful in other overhead work applications within the construction industry (such as setting anchors). Furthermore, there are undoubtedly applications for a similar type of device in other industries doing overhead work as well.

Construction equipment manufacturers can use the results of this study to direct their development efforts and to refine their equipment designs. Our research has shown a market need for a device that reduces neck and shoulder disorders in the construction industry. The research has also pinpointed specific design features that are effective and practical in the construction environment. Our results clearly show that the use of a camera system is promising. This information clearly provides a jumping off point for future development activities for manufacturers.

The results of our study may also be useful to health and safety researchers who are embarking on intervention studies in the workplace. We have developed a methodology that was found to be both successful at determining specific design features that were effective at reducing neck and shoulder injuries, and practicable for the physical and organizational environment within the construction industry. Our approach provides a framework for analysis that allows for participative design through early and consistent involvement of workers and contractors in identifying and assessing design opportunities. Our use of a number of different criteria for assessing the effectiveness of the intervention (biomechanical, subjective, performance/productivity) follows good ergonomic design practice and allows for triangulation in determining the best design features. This methodology can be applied by health and safety researchers to other interventions intended for use in the workplace. This report is not written in detail for the research audience. Our academic publications will cover the study methods and results in considerable more depth.

5.3. Policy-related interactions undertaken This project focused on an early stage of the research cycle – the development of specific design features on the intervention device – rather than policy changes in the workplace. However, we were attentive to such issues throughout the project. For example, in the development of the device, researchers met with Mr. Gord Theisen to review safety features on the device to ensure that design elements comply with WorkSafeBC standards.

6. Dissemination An effort was made to ensure wide dissemination of information to all relevant parties throughout the project. Knowledge transfer activities have targeted stakeholders in multiple ways.

6.1. Professional Audiences Meetings were held within British Columbia throughout this project with representatives of:

• The Council of Construction Associations (COCA)

• Local plumbing, electrical, and sheet-metal unions (SMW Local 280, IBEW Local 213, UA Local 170) throughout the project.

Project information was exchanged with other BC construction associations:

• SMACNA-BC

• MCABC

• ECABC

Several presentations were made to contractors and unions in the US:

• Santa Clara and San Benito Counties Building and Construction Trades Council: general meeting


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• Rosendin Electric health & safety, including director and staff, and company superintendents: health/safety meeting

• Cal/OSHA Ergonomics: meeting of health & safety professionals

• Laborers Training and Retraining Trust Fund for Northern California. Vic Macias, Director of Training.

• National Electrical Contractors Association (NECA) - Northern California Chapter: Safety Committee meeting

• McCarthy General Contractor: Oakland Kaiser Permanente construction site visit with safety director, and presentation to subcontractors at general meeting

• Alameda Building Trades Council: general meeting

• UA Local 393 Joint Labor Management Committee Meeting (South Bay Pipe Trades Training Center

• San Francisco Building Trades Council: Aug 26, 2008

• A pamphlet detailing the project was printed and distributed to contractors, sub-contractors, and workers (see appendix).

• A website (www.sfu.ca/drilling) was designed and updated on a regular basis to reflect project status.

• An article was published in WorkSafeBC magazine (Sept, 07) describing the objective of the study, the developed intervention devices and future protocols. Photographs of the intervention devices were included in the article directed at our target audiences of construction companies and workers.

• The American Society of Safety Engineers’ Professional Safety Magazine (Nov 07) and the Association of Canadian Ergonomists (Fall 08) also profiled the project in their publications.

6.2. Scientific Audiences • A scientific conference paper was prepared and presented at the Association of Canadian

Ergonomists 39th Annual Conference in Gatineau Quebec (Fall 2008). This paper outlines the work done in the pilot project. It summarizes results to date and supports the direction for the larger study. The audience at this conference includes ergonomics consultants/practitioners, researchers and industry specialists who are responsible for implementing intervention in the workplace.

• The project was presented at the 18th Annual Construction Safety Conference& Exposition on February 13, 2008 in Rosemont, IL sponsored by the Construction Safety Council and the Center for Construction Research and Training (CPWR). The presentation was entitled "An ergonomic solution to overhead drilling on construction sites."

• The project was selected as one of three finalist for the 2008 Safety Innovation Award held at the 4th Annual Safety Expo at Sacramento State University on April 1, 2008 sponsored collectively by the Golden State Builders Exchange (GSBE).

• A manuscript outlining the pilot project has been submitted to Applied Ergonomics (March 2009) and is currently being reviewed for publication.

• A follow-up paper will be submitted to Applied Ergonomics outlining the final results in late 2009.

• We will submit our results for presentation at the 41st ACE conference, and the Health and Safety Canada IAPA (Industrial Accident Prevention Association) Conference and Trade Show, a forum to share current occupational health and safety innovations.


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7. Acknowledgements This research was made possible by the Workers’ Compensation Board of British Columbia (WordSafeBC) Focus on Tomorrow research program. The research project had the support from Council of Construction Associations, BC and Yukon Building Trades Council, SMW Local 280, IBEW Local 213, UA Local 170, SMACNA-BC, MCABC, and ECABC. The research team is also grateful for the voluntary participation of the construction workers and the following companies: Ledcor, GML Mechanical, Crosstown Metal Industries Ltd., Sasco Systems Ltd., PCL Constructors Inc., Fred Welsh Ltd., Apollo Sheet Metal Ltd., and Dominion Construction.


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8. References

Albers, J., Estill, C., MacDonald, L. 2005. Identification of ergonomics interventions used to reduce musculoskeletal loading for building installation tasks. Applied Ergonomics, 36, 427-439.

Flatow, E., Soslowsky, L., and Ticker, J.E.A., 1994. Excursion of the rotator cuff under the acromion: Patterns of subacromial contact. American Journal of Sports Medicine, 22, 779-788.

Hagberg, M. Electromyographic signs of shoulder muscle fatigue in two elevated arm positions. American Journal of Physical Medicine. 1981; 60(3):111-21.

Holmstrom EB, Lindell J, Moritz U, Low back and neck/shoulder pain in construction workers: occupational workload and psychosocial risk factors. Part 2: Relationship to neck and shoulder pain. Spine. 1992 Jun;17(6):672-7.

Hunting KL, Welch LS, Cuccherini BA, Seiger LA. "Musculoskeletal Symptoms among Electricians." American Journal of Industrial Medicine 25:149-163, 1994.

Lindberg, J.; Wos, H.; Norlander, S.; Jakus, R. Support stand for hand-held tools used for overhead work. Bygghalsan Bulletin. 91-09-16. English Abstract.

McAtamney, L, and Corlett, E.N., 1993. RULA: A method for the investigation of work-related upper limb disorders. Applied Ergonomics, 24, 91-99.

Nussbaum, M.A. (2003) Postural stability is compromised by fatiguing overhead work. American Industrial Hygiene Association Journal , 64, 56-61.

Olson, P. Musculoskeletal disorders of the neck-shoulder region related to working positions in the construction industry. Bygghalsan Bulletin.: 1987-05-01.English Abstract.

Persson, J., and Kilbom, A., 1983. VIRA – en enkel videofilmteknik för registrering och analys av arbetsställningar och rörelser. Undersökningsrapport, 10, 23. (English Summary)

Rempel, D., Star, D., Gibbons, B., Barr, A., and Janowitz, I., 2007. Overhead Drilling: Development and evaluation of a new device. Professional Safety, 11, 30-35.

Rosecrance, J., Cook, T., and Zimmermann, C., 1996. Work-related musculoskeletal disorders among construction workers in the pipe trades. Work, 7, 13-20.

Sandmark, H., and Nisell, R., 1994. Measurement of pain among electricians with neck dysfunction. Scandinavian Journal of Rehabilitation Medicine, 26, 203- 209.

Sigholm, G.; Herberts, P.; Almstrom, C.; Kadefors, R. Electromyographic analysis of shoulder muscle load. Journal of Orthopaedic Research. 1984; 1(4): 379-86.

Welch L, Hunting K, Kellogg J. Work-related musculoskeletal symptoms among sheet metal workers. American Journal of Industrial Medicine. 1995; 27:783-791.

WorkSafeBC, http://www2.worksafebc.com/Portals/Construction/Statistics.asp. Accessed March 13, 2009.


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WorkSafeBC,http://www.worksafebc.com/publications/health_and_safety/bulletins/constructive_ideas/assets/pdf/ci0616.pdf Accessed May 5, 2009


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Appendix A. Tables

Table 1: Drilling Subtask Descriptions

Usual Drilling Method Inverted Drill Press

Targeting • Time after departure when subjects navigate and position themselves beneath the next marked location.

• May require moving and positioning a ladder or lift to the marked locations.

• Starts with subject either visually finding the next marked location by looking up or when subject begin to move towards the next hole.

• Includes lateral movements of the drill, ladder, or lift to ensure proper alignment before approach.

• Time after departure when subjects navigate and position themselves beneath the next marked location.

• Starts with subject either visually finding the next marked location by looking up or when subject begin to move towards the next hole.

• Includes lateral movements of the inverted drill press to ensure proper alignment before approach.

Approach • Time after targeting • Begins when subjects start to climb

the ladder, or raise a lift. • Ends when the drill bit contacts

ceiling.

• Time after targeting • Begins when subjects start to crank

the column up. • Includes subtle lateral movements

to make fine adjustments to hit the target.

• Ends when the drill bit contacts the ceiling.

Drilling • The time between bit-concrete penetration and the drill bit releasing from the ceiling

• Audibly discernable based on the pitch change when the drill bit is in contact with the ceiling.

Departure • Time after drilling and before targeting.

• Starts once the drill bit has left the ceiling and includes all time during the decent from the ladder or lowering of the lift.

• Ends once the subject begins targeting for the next hole.

• Time after drilling and before targeting.

• Starts once the drill bit has left the ceiling and includes all the time during which the column is being lowered.

• Ends once the subject begins targeting for the next hole.


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Table 2: Mean (SD) Fatigue Ratings by method, N=16


Neck 2.2 (1.1) 2.1 (1.6) 0.7 (0.8)

Shoulder 3.6 (0.9) 0.6 (0.7) 0.4 (0.6)

Hand and Forearm 2.5 (1.6) 0.6 (0.7) 0.4 (0.6)

Lower Back 1.9 (1.5) 0.4 (1.0) 0.2 (0.5)

Leg 1.0 (1.1) 0.3 (0.6) 0.1 (0.3)

Table 3: Fatigue mean ranks, Friedman test, and Wilcoxon Post Hoc. N=16.

Mean Ranks Friedman test Wilcoxon Post Hoc

Usual Method



Chi-Square p-value Pair-wise p-values

Neck 2.4 2.3 1.3 13.1 .001 UM v IDPw/C: .001 IDP v IDPw/C: .005

Shoulder 3.0 1.6 1.4 28.3 .000 UM v IDP: .000 UM V IDPw/C: .000

Hand and Forearm

2.7 1.7 1.6 16.3 .000 UM v IDP: .002 UM v IDPw/C: .002

Lower Back 2.7 1.7 1.6 20.4 .000 UM v IDP: .003 UM v IDPw/C: .002

Leg 2.5 1.9 1.6 12.6 .002 UM v IDP: .027 UM v IDPw/C: .006


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Table 4: Mean (SD) Percent Time Shoulder Angle Bins. Repeated Measures ANOVA and Paired Sample T-Test.

Degrees

Usual Method N=13

Inverted Drill Press N=14


N=14

F (p-value)

0 to 45 71.5 (20.3) 50.2 (29.8) 49.4 (25.2) 5.158 (0.014) UM – IDP: 0.019

UM – IDPw/C: 0.027

45 to 60 13.7 (11.0) 23.3 (14.0) 23.6 (15.0) 3.317 (0.053)

60 to 90 9.4 (11.0) 22.8 (17.8) 24.4 (17.0) 4.571 (0.021) UM – IDP: 0.014

UM – IDPw/C: 0.037

90+ 5.3 (7.3) 3.6 (7.3) 2.6 (4.3) 0.591 (0.562)

Table 5: Mean (SD) percent time in neck extension. Repeated Measures ANOVA and Paired Sample T-Test. N=16.

Usual Method Inverted Drill Press


F (p-value)1

% Time in Neck Extension

72.5 (13.3) 72.2 (15.4) 49.8 (23.1) 12.350 (.000) UM – IDPw/C: .001 IDP – IDPw/C: .001

1Only significant results shown for the post-hoc test.


21

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Table 6: Mean (SD) Usability Ratings, N=16.


Ease 1.6 (0.9) 2.6 (1.0) 2.5 (1.2) Setting Up

Speed 1.7 (0.9) 2.9 (1.2) 2.6 (1.2)

Ease 1.7 (0.8) 2.5 (1.2) 2.3 (1.0)

Speed 1.7 (0.8) 2.5 (1.1) 2.5 (1.1)

Accuracy 1.5 (0.6) 2.8 (1.0) 2.7 (1.4)

Control 1.8 (1.0) 2.6 (1.1) 2.3 (0.9)

Moving to the next hole

Stability 2.1 (0.9) 2.4 (1.2) 2.6 (1.0)

Ease 1.5 (0.6) 2.5 (0.9) 2.3 (1.1) Making Adjustments

Speed 1.6 (0.8) 2.6 (1.0) 2.7 (1.2)

Ease 1.4 (0.6) 1.2 (0.4) 1.2 (0.4) Activating the Drill

Speed 1.4 (0.5) 1.3 (0.6) 1.3 (0.6)

Ease 2.8 (0.9) 1.3 (0.4) 1.3 (0.4)

Speed 2.2 (0.8) 1.1 (0.3) 1.4 (0.7)

Accuracy 1.7 (1.0) 2.3 (0.8) 2.1 (1.2)

Control 2.1 (0.9) 1.6 (0.7) 1.6 (0.7)

Stability 2.6 (1.1) 1.9 (0.7) 2.1 (0.7)

Drilling

Feel (Handling)

2.4 (1.0) 2.3 (1.1) 2.3 (0.9)

Ease 2.3 (0.9) 1.3 (0.6) 1.3 (0.8) Knowing when the drilling is complete Speed 2.0 (0.8) 1.4 (0.8) 1.3 (0.8)

Looks (Aesthetics)

1.9 (1.1) 1.9 (1.1) 2.0 (1.3) General

Durability 1.6 (0.8) 2.3 (0.9) 2.6 (1.4)


22

- FINAL REPORT -

Table 7: Mean Usability Ranks by method, Friedman Test, N=16.

Mean Ranks Friedman Test



Chi-Square p-value

Ease 1.56 2.34 2.09 6.936 .031 Setting Up

Speed 1.63 2.31 2.06 5.277 .071

Ease 1.63 2.28 2.09 4.776 .092

Speed 1.63 2.16 2.22 4.844 .089

Accuracy 1.31 2.50 2.19 14.923 .001

Control 1.56 2.34 2.09 6.520 .038

Moving to the next hole

Stability 1.78 1.94 2.28 3.526 .172

Ease 1.84 2.69 1.47 18.136 .000 Making Adjustments

Speed 1.53 2.22 2.25 7.860 .020

Ease 2.25 1.88 1.88 4.571 .102 Activating the Drill

Speed 2.13 1.94 1.94 1.143 .565

Ease 2.84 1.59 1.56 25.442 .000

Speed 2.66 1.59 1.75 15.674 .000

Accuracy 1.72 2.28 2.00 4.050 .132

Control 2.22 2.00 1.78 2.000 .368

Stability 2.34 1.75 1.91 4.311 .116

Drilling

Feel (Handling)

2.22 2.09 1.69 4.158 .125

Ease 2.56 1.69 1.75 12.842 .002 Knowing when the drilling is complete Speed 2.47 1.78 1.75 9.657 .008

Looks (Aesthetics)

2.00 2.03 1.97 .050 .975 General

Durability 1.66 2.06 2.28 5.024 .081


23

- FINAL REPORT -

Table 8: Pair-wise Wilcoxon Signed Rank Post Hoc Test for Significant Results from Friedman Test

Usual Method VS


Usual Method VS


Inverted Drill Press VS


Setting up: Ease 0.025 0.062 N/A

Moving to the next hole: Accuracy

0.001 0.006 N/A

Moving to the next hole: Control

N/A N/A N/A

Making adjustments: Ease

0.017 0.037 N/A

Making adjustments: Speed

0.022 0.020 N/A

Drilling: Ease 0.001 0.001 N/A

Drilling: Speed 0.003 0.005 N/A

Knowing when the drilling is complete: Ease

0.004 0.010 N/A

Knowing when the drilling is complete: Speed

0.013 0.022 N/A


24

- FINAL REPORT -

Table 9: Mean (SD) subtask completion times. Repeated Measures ANOVA and Paired Sample T-Test. N=16



F (p-value)1

Targeting 9.3 (1.3) 24.7 (6.9) 26.6 (7.0) 6.4 (.016)2 UM – IDP: .026

UM – IDPw/C: .016

Approach 10.0 (1.3) 19.5 (3.7) 25.2 (4.9) (.002) UM – IDP: .018

UM – IDPw/C: .006

Drilling 20.1 (3.8) 22.5 (5.1) 17.2 (2.0) 1.9 (.180)2

Departure 8.8 (2.6) 9.8 (1.4) 10.7 (2.5) 0.3 (.773)

Overall 42.4 (5.9) 76.4 (11.5) 79.6 (11.6) 8.7 (.001) UM – IDP: .004

UM – IDPw/C: .007 1Spherical assumption met unless indicated 2Greenhouse-Geisser degrees of freedom correction


25

- FINAL REPORT -

Appendix B. Questionnaires

Comparison Questionnaire

Subject #: F __ __ – __ __ Date: _____ / ____ /_____ mm dd yy

Rank the drilling method for each characteristic, where 1 is the best/most favourable, 2 is the second best, and 3 is the worst/least favourable.



System

Example

a. Moving/Mobility

b. Ease of Use

c. Accuracy

d. Work Speed

e. Comfort

f. Stability

g. Adjusting

h. Durability

i. Knowing when drilling complete

j. Feel (Handling)

k. Looks

l. Overall

1st

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________

2nd

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________

3rd

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________

__________


26

- FINAL REPORT -


Subject #: F __ __ – __ __

Date: _____ / ____ /_____

mm dd yy

1. On a scale of 1-5 where 1 is very good and 5 is very bad, rate this method for the following characteristics:

Very Good Very Bad Setting Up a. Ease 1 2 3 4 5 b. Speed 1 2 3 4 5

Moving to the next hole a. Ease 1 2 3 4 5 b. Speed 1 2 3 4 5 c. Accuracy 1 2 3 4 5 d. Control 1 2 3 4 5 e. Stability 1 2 3 4 5

Making adjustments a. Ease 1 2 3 4 5 b. Speed 1 2 3 4 5

Activating the drill a. Ease 1 2 3 4 5 b. Speed 1 2 3 4 5

Drilling a. Ease 1 2 3 4 5 b. Speed 1 2 3 4 5 c. Accuracy 1 2 3 4 5 d. Control 1 2 3 4 5 e. Stability 1 2 3 4 5 f. Feel (Handling) 1 2 3 4 5

Knowing when the drilling is complete a. Ease 1 2 3 4 5 b. Speed 1 2 3 4 5

General a. Looks (Aesthetics) 1 2 3 4 5 b. Durability 1 2 3 4 5

2. What would you change to improve the ease of using this method?


27

- FINAL REPORT -

3. Fatigue (Tiredness) On a scale of 0-5, where 0 is no fatigue and 5 is very fatigued; please rate the following after you used this method:

No Fatigue Very Fatigued a. Neck 0 1 2 3 4 5 b. Shoulders 0 1 2 3 4 5 c. hands and Forearms 0 1 2 3 4 5 d. Lower Back 0 1 2 3 4 5 e. Legs 0 1 2 3 4 5

4. How would you change this method to reduce pain or fatigue to the operator?

5. What three things do you like about this method?

1. _________________________

2. _________________________

3. _________________________

6. What three things do you dislike about this method?

1. _________________________

2. _________________________

3. _________________________

7. If available, would you use this method again next time? Yes / No

Why or why not?

8. Did you notice any safety issues (pinch-points, sharp edges, stability, etc)? Yes / No

If yes, what and where are they?


28

- FINAL REPORT -

Usual Method

Subject #: F __ __ – __ __

Date: _____ / ____ /_____

mm dd yy











29

- FINAL REPORT -





1. _________________________

2. _________________________

3. _________________________


1. _________________________

2. _________________________

3. _________________________


Why or why not?




30

- FINAL REPORT -











Subject #: F __ __ – __ __

Date: _____ / ____ /_____

mm dd yy


31

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1. _________________________

2. _________________________

3. _________________________


1. _________________________

2. _________________________

3. _________________________


Why or why not?




32

- FINAL REPORT -

Overhead Drilling Project Subject #: F __ __ – __ __

Subject Demographics

Date: ________ /_________/ _________ (mm/dd/yy)

Tape Number(s): _____________________________________

Age: _______________ Gender: M / F Dominant Hand: Right / Left

Height: _____________Ft _____________ Inches Weight: _______________Lbs

Trade: Electrical Plumbing/Pipefitting Sheetmetal Apprentice / Journeyman

Years of Experience: _______________ Days with drilling in the past year: _____________ Days/Month

Site Information

Contractor / Company: ________________________________________________________________

Project: ____________________________________________________________________________

Location of Project: ___________________________________________________________________

Weather Conditions: __________________________________________________________________

Ceiling Height: _______________________________________________________________________

Drill (Make, Model): ___________________________________________________________________

Drill bit: ____________________________________________________________________________

# of Holes: __________________________________________________________________________

What’s being installed: ________________________________________________________________

General Comments: __________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

___________________________________________________________________________________

Data Collector’s Initials: _______________________________________________________________

All rights reserved. The Workers’ Compensation Board of B.C. encourages the copying, reproduction, and distribution of this document to promote

health and safety in the workplace, provided that the Workers’ Compensation Board of B.C. is acknowledged. However, no part of this publication may be copied, reproduced, or distributed for profit or other

commercial enterprise or may be incorporated into any other publication without written permission of the Workers’ Compensation Board of B.C.

Additional copies of this publication may be obtained by contacting:

Research Secretariat 6951 Westminster Highway Richmond, B.C. V7C 1C6

Phone (604) 244-6300 / Fax (604) 244-6299 Email: [email protected]

2010-10-21 01-Worksafe BC Report Feb2010

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