Civil Engineering Reference
In-Depth Information
controls suffer from
functionitis,
a common disease that affectssystems designers. Here is
how the designers think: “Let's program every function we can think of. It does not cost
anything extra for the buyer.” So here I am with 199 functions I never asked for.
When I installed the machine I must have pressed the wrong button, because Russian
command words showed up in the ten-character display. There were about ten different
command words, none of which could be understood. So I wrote them down and
identified their meaning in a Russian-English dictionary that I found on the Web. I could
then translate the commands and switch the language to English. This little exercise took
me about 2 hours—wasted time indeed.
CODING OF OTHER ITEMS TOUCHED BY THE HAND; HAND
TOOLS AND PARTS IN MANUFACTURING
Coding principles can be applied to any items that are touched or held; it could be parts to
be assembled as well as hand tools. Hand tools and parts can be coded by location, color,
and labeling. For example, color coding can be used as a scheme for organizing a
workstation, by applying the same color to parts bins and hand tools that belong together.
Color coding of parts is nothing new. It has long been used in electronics for marking
resistors, transistors, and capacitors, and this simplifies electronic assembly. In fact, these
parts are also shape-coded, so that it would be difficult to confuse a transistor with a
capacitor. Handtools are often colored with different colors. This makes it easier to find
them.
6.8
EMERGENCY CONTROLS
The design and location of emergency controls requires particular attention, since it is
crucial to be able to find them quickly (Atherton, 1986). Emergency situations are
stressful, and operators are likely to make mistakes. Emergency controls must therefore
be particularly well designed to allow fast action without any errors. Some design
recommendations are summarized in Table 6.5.
TABLE 6.5
Recommendations for the Design of
Emergency Controls
Position emergency controls away from other frequently-used controls, thereby lessening the risk
of inadvertent activation
Make emergency controls easy to reach; put them in a location that is natural for the worker to
reach
Make emergency controls large and easy to activate; e.g., use a large rather than a small pushbutton
Color emergency controls red
Many types of emergency control are used. Some industrial machinery have “dead
man's” switches. As long as this type of switch is actively pressed, the machinery keeps
going. If the pressure is released, the machinery stops. Some types of industrial
machinery have an automatic switch or function in case the worker inadvertently comes
