Civil Engineering Reference
In-Depth Information
FIGURE 6.7
Shape-coded controls for
airplanes.
EXAMPLE
Some years back I worked on a project sponsored by U.S. Bureau of Mines to standardize
controls for the roof bolters that are used in underground coal mines. In one mine we
found the roof bolter in Figure 6.8. The figure shows Brian to the left and the roof bolter
with 15 hydraulic controls. The controls used to be identical. However, the operator had
welded on extensions and added on shape coding to the controls. This was obviously a
very difficult machine to handle and the shape coding simplified the operation.
Shape coding of controls can also be used in industrial situations. In fact, sometimes
operators add their own shape coding. During investigations following the Three Mile
Island nuclear accident, many intriguing principles of shape coding used by power plant
operators were discovered. At one plant, operators had coded identical control levers with
beer bottles.
CODING BY LABELING
A label may be used to describe a control. The label can be put above, underneath, or on
top of the control. The location of the label does not really matter as long as it is clearly
visible and the wording reads from left to right (Chapanis and Kinkade, 1972). Vertical
labels take longer to read and should not be used. One problem with labels is that they
might not survive in a harsh industrial environment. In particular, printed characters may
be soiled or destroyed. Embossed labels are therefore often used (Loewenthal and Riley,
1980). As with color coding and shape coding, the use of label coding implies a double
reaction time; the label has to be read and understood before action can be taken.
