An ergonomic retrofit
While recent tremors near campus have refocused attention on the seismic retrofit of Memorial Stadium, bioengineering professor David Rempel’s portion of the project concerns a different kind of vibration.
The Memorial Stadium construction, underway since spring and due for completion next summer, necessitates boring some 40,000 holes into concrete foundations with drills weighing up to 45 pounds—potentially exposing drill operators to the harmful effects of muscle injury, dust, and vibration exposure.
“These workers typically have pain and fatigue in the wrists, shoulders and back; some have also experienced damage to the nerves in the fingers,” says Rempel, director of the Ergonomics Program in UC’s Center for Occupational and Environmental Health. From the Center’s lab at the Richmond Field Station, the Ergonomics Program has been designing ways to minimize the adverse health effects of such labor on workers.
One idea has been the highway drill jig, a tool to reduce fatigue for workers drilling into concrete. The jig holds the drill while exerting over 100 pounds of force. It requires no electrical power.
“The jig is a support system for the drill, so the worker doesn’t have to hold it,” says Rempel. “It advances easily with a crank into the concrete and isolates the worker from vibration, force and dust.”
The lab drew from its experience designing an overhead drill press, which lifts drills to ceilings to drill into concrete without workers needing to look up or exert high force. Contractors using the tool to drill holes for a bridge upgrade on Highway 80 suggested expanding its use to drill horizontally into concrete walls.
“The drilling on the bridge ruined our first jig,” Rempel laughs. “We had a grant to develop a stronger jig that could also drill horizontally. The height and angle of drilling were adjustable, and we had to make sure the action of advancing the drill into concrete didn’t push the whole assembly over.”
Lab engineers redesigned the jig, and then brought it back into the field. For the overhead jig, engineers developed and field tested seven prototypes before they got it right.
“The workers were skeptical at first, but then they tried it for ten holes and said they didn’t want to go back to the old way,” says Rempel.
The new jig will also be used for structural bridge work along Highway 13 in Oakland, along the San Mateo Bridge and at other commercial construction sites around the Bay Area.
A powered jig is being developed by Rempel’s lab to lay tracks for an extension of BART to Livermore. This jig will not only drill down by itself but it will also be able to lift the drills up when the hole is done.
The lab is also working on a series of tools for dental hygienists, who have to apply a high-pinch force to scaling tools while removing plaque from teeth. Past projects have also included split keyboards, computer mice, workstations and other ergonomic improvements for such manufacturers as Apple, Microsoft, Ranin, Logitech and Herman-Miller.
“We apply biomechanical principles that will help reduce the force a worker is applying to the tool,” Rempel says. “We design tools and work stations to fit people’s body sizes while also reducing how long workers have to apply forces near their strength.”