Civil Engineering Reference
In-Depth Information
• Lack of experience of manual work
• New job
• Back from vacation
Inappropriate leisure activities
• Insufficient rest due to working in a second job
• Knitting, playing musical instruments, playing tennis, bowling, home
• improvement work
Pre-existing conditions
• Arthritis, bursitis, other joint pain
• Nerve damage
• Circulatory disorders
• Reduced estrogen level
• Small hand/wrist size
Note that many of the listed causes have not been confirmed by research, since they are difficult to
investigate, and it takes a long time to accumulate epidemiological data.
complaints seriously. There are often simple modifications and additions to workstations
that can alleviate some of the problems. For example, VDT operators often ask for a soft
wrist rest, a split keyboard, a lower typing surface, or a footrest. These are inexpensive
modifications, and one should not question the utility of such measures.
11.4
DESIGN GUIDELINES TO MINIMIZE REPETITIVE
MOTION INJURY
Table 11.4 illustrates several engineering guidelines that can be used to minimize RMI.
The assumption for presenting these guidelines is that the working environment, the task,
and the workstation can be improved or redesigned by using various measures.
TABLE 11.4
Guidelines for Reducing RMI
through Product Design, Process Engineering,
Workstation Design and Use of Appropriate
Handtools
Guidelines for hand posture
• Watch out for sudden flexion or extension of the hand or fingers
• Avoid extreme ulnar deviation and radial deviation
• Avoid operations that require more than 90° wrist rotation
• Keep forces low during rotation or flexion of the wrist
• For operations that require finger pinches keep the forces below 10 N; this represents 20% of the
weaker operators' maximum pinch strength
Guidelines for handtools
• Cylindrical grips should not exceed 5 cm (2 in) in diameter
• Avoid gripping that spreads the fingers and thumbs apart by more than 6 cm (2.5 in)
• Use hand tools that make it possible to maintain the wrist in a neutral position (see Figure 8.2)
• Guidelines for workstation design
• Keep the work surface low to permit the operator to work with elbows to the side and wrists in a
neutral position
