Principles of equipment layout

Optimum location

Ideally, all equipment would be placed in the optimum location for its purpose. This would depend on the user's characteristics, such as their size, and their movement, vision and hearing capabilities. Equipment should be located in the optimum (best) space, according to some criterion of use, such as convenience, accuracy, speed or strength to be applied. Workplace layout can be considered in terms of the optimum, and the overall dimensions or space. Optimum dimensions define the most desirable space for the location of equipment - highest priority equipment should be placed here. Overall dimensions define the acceptable, but not necessarily the most desirable, dimensions or space - less important equipment, for example, that used periodically during normal operations, should be placed within this region. The overall space will always include, and generally be larger than, the space defined by the optimum dimensions. Both sets of dimensions are determined by using anthropometric data of the user population (see the anthropometry topic for more information). Unfortunately, it is not often possible to place all equipment in its optimum position due to lack of space. A large display may need to be positioned away from you in order for you to see it all clearly, but its associated control may need to be positioned close to you for a fast response. In this case, you must set priorities and make compromises. Several other principles can help you to do this, and these are usually applied in the following descending order:

Importance principle

Important equipment should be placed in convenient locations. 'Importance' is determined by how critical a piece of equipment is in terms of achieving the task or goals of the system. Emergency equipment should be placed in readily accessible positions (somewhere within the overall workspace), but not necessarily in the optimum workspace.

Frequency of use principle 

Frequently used equipment should be placed in convenient locations, close to or preferably, in front of you.

Sequence of use principle

Equipment should be arranged to take advantage of any sequences or patterns of use that occur during a task. If a number of controls are normally operated in a particular sequence, then they and their corresponding displays should be arranged on the panel in that order, from left to right, or from top to bottom. Thinking time is reduced as you don't have to remember a particular order of actions, and movement is reduced as related equipment will be located close to each other.

Grouping principle

Equipment should be grouped according to its function. For example, equipment that is related to a particular task, such as temperature displays and temperature controls should be grouped together. This grouping can be highlighted by the use of colour, labelling, demarcation lines or simply by placing groups of items in rows. Look on your keyboard - text keys, numeric keys, and cursor control keys are all positioned together in groups. 


Note: In practice, these principles cannot always be applied. In these cases, you should assess any risks to ensure that tasks can be performed with minimal risk to the user, equipment or others people.

Equipment panel design

Panel shape

In work places such as control centres, displays and controls may be mounted within panels to help create a 'workstation'. The panels may have a variety of shapes depending upon the types of displays or controls that are to be included. These panels may be flat, sectional, or curved.

Flat panels are easy to build, but may be inconvenient to use when the panel is large because the outer edges might be beyond your maximum angle for clear vision, or your maximum manual reach.

Sectional panels are also easy to build. If sectional surfaces are built at appropriate angles, all points will be within your reach and vision.

Curved panels are the best to use from the user's point of view. The workstation can be designed so that all points are within the overall manual reach dimensions and all surfaces are perpendicular to the line of sight. However, curved panels may be difficult and expensive to build.

Panel contours

The contours or slopes of the panel should reflect your visual and manual reach capabilities. 

Equipment layout design guidelines

Orientation of displays

If a panel contains a large number of dials, you may have difficulty in finding the one you want. Using patterns can help, especially in check reading (where you just need to see if a pointer is in a certain position, for example) - if the dials are oriented on a panel so that each 'normal' reading appears in the same position, and any deviant pointer will stand out clearly.

Look at the example below - it shows patterning to help the understanding of displays. As the 32 dials of the right hand bank are aligned to point in the same direction when indicating 'normal', you can check them as quickly as you can the four dials on the left, which are not aligned when indicating normal. (For more information on appropriate displays, see the displays topic.)

Location of controls

The optimum area for location of controls is between hip and shoulder height and at a maximum distance of arm's length. Associated controls and displays should be placed near each other, with the control below the display or to the right so that your hand does not obscure the reading. If groups of displays must be positioned separately from their controls, then the displays and controls should be positioned in the same order and arrangement so that there is control-display compatibility.

Discrimination of controls

Where there is a large number of controls on a panel, they should be readily distinguishable from one another by appearance, texture, or shape, as well as by adequate labelling. A row of identical knobs or switches may be considered aesthetically pleasing but can be very confusing.

Emergency operation

You should be alerted quickly to emergency situations and then be able to locate the fault with minimum delay. Any alarm system should be a combined visual and auditory warning. The equipment for dealing with the emergency, for example, displays and controls, should be obvious and readily accessible. People under stress, for example, in emergencies, tend to revert to well-rehearsed habits. This means that any 'expected' relationship between control and display becomes even more important in cases of emergency. For example, controls should be turned to the right to increase. (For more information on appropriate control movement, see the controls topic.)

User comfort

To reduce muscular fatigue, you should be given tasks that allow you to frequently change your posture during your working day. Frequently used controls, or controls that need an amount of strength or particular dexterity, should be positioned close to you, as your hand movement is most accurate nearer to the body. Accuracy and strength are reduced if control movement is across the body or in a direction away from the body.