A new method for overhead drilling David Rempel*, Demetra Star, Alan Barr, Billy Gibbons and Ira Janowitz Department of Bioengineering, University of California at Berkeley, Berkeley, CA 94720, USA In the construction sector, overhead drilling into concrete or metal ceilings is a strenuous task associated with shoulder, neck and back musculoskeletal disorders due to the large applied forces and awkward arm postures. Two intervention devices, an inverted drill press and a foot lever design, were developed then compared to the usual method by construction workers performing their normal overhead drilling activities (n ¼ 14). While the intervention devices were rated as less fatiguing than the usual method, their ratings on usability measures were worse than the usual method. The study demonstrates that the intervention devices can reduce fatigue; however, additional modifications are necessary in order to improve usability and productivity. Devices designed to improve workplace safety may need to undergo several rounds of field testing and modification prior to implementation. Keywords: design; construction; shoulder; musculoskeletal disorders; fall protection 1. Introduction In the USA, the construction sector has the highest rate of non-traumatic soft tissue injuries to the neck, back and upper extremity, with incidence rates of 622 per 10,000 full-time employees (Washington State Fund 2000). Increasing hours of overhead work is strongly associated with shoulder, elbow and wrist pain and disorders (Hagberg 1981, Olson 1987, Holmstrom 1992). One of the most physically demand- ing tasks is overhead drilling into concrete for the insertion of anchor bolts in order to hang pipes, ducts, wiring and equipment (Welch 1995, National Institute for Occupational Safety and Health 2002). The work is primarily performed by the sheet metal, plumbing and electrical trades. The task is usually performed on a ladder or scaffold and involves pushing a hammer drill upward toward the ceiling while the drill bit cuts into concrete or metal (Figure 1). Rotary hammer drills weigh up to 10 kg (100 N) and an additional upward force of 200 N can be applied during drilling. The drill bits are usually 1–2 cm in diameter. The drilling depth is between 1 and 5 cm depending on the size of the anchor bolt intended for the hole. After the hole is drilled, the anchor bolt is hammered into the hole and a hanger is screwed into the anchor bolt, then pipes, ducts or trays are attached to and supported by the hangers. High arm, shoulder and torso forces are required to support the weight of the drill and push the drill upward during drilling. Since the work is usually done on a ladder and near the ceiling, it can also involve awkward neck and shoulder postures. The other health risks associated with this task are falling and exposure to dust, noise and vibration. Devices for overhead drilling have been developed on an ad hoc basis for commercial construction jobs, but none of the devices has undergone usability evaluations or been involved in a process of redesign and testing in preparation for widespread use. The long-term objectives of this research are to design and evaluate interventions for overhead drilling with the goal of reducing arm, shoulder and back load and risks for musculoskeletal disorders (Rempel et al. 2007). Other important goals are to reduce the risk of falls and reduce exposure to noise, dust and vibration while not interfering with productivity. This paper presents the results of the first generation intervention device for overhead drilling – devices that use a foot lever or inverted drill press design to raise a hammer drill on a column. 2. Methods 2.1. Device designs The research team borrowed from past designs and involved experienced construction workers in the design and development of two devices for field testing: an inverted drill press (Figure 2); a foot-lever drill press *Corresponding author. Email: david.rempel@ucsf.edu Ergonomics Vol. 52, No. 12, December 2009, 1584–1589 ISSN 0014-0139 print/ISSN 1366-5847 online Ó 2009 Taylor & Francis DOI: 10.1080/00140130903254338 http://www.informaworld.com Downloaded By: [University of California Berkeley] At: 18:06 7 January 2010