Working Height and Workstation Design in Production

Workstation design starts at the elbow

Picture two operators working at the same bench on an assembly line: one is 1.60 m tall, the other 1.85 m. The bench is 90 cm high and nobody sees it as a problem, until one goes to the workplace physician with shoulder pain and the other with back pain. If workstation design does not start from the dimensions of the person doing the work, even the best machine will cause strain.

Art. 5 of Law No. 6331 lists the following among the principles of risk prevention the employer must follow: taking care, in the design of workplaces and the choice of work equipment, working methods and production methods, to adapt the work to the individual, in particular to prevent or, if this is not possible, minimise the adverse effects of monotonous work and production pace. Anthropometric design principles for workstations at machinery are set out in the TS EN ISO 14738 standard.

In practice, the basic reference point is elbow height: the height of the elbow from the floor when the worker stands upright with the upper arm beside the body and the forearm parallel to the floor. The working height is set relative to this point. The most common mistake here is measuring the bench surface. What matters, however, is the point where the hand works: if a fixture or part 20 cm high is placed on the bench, the working point is 20 cm above the bench.

Working height for precision, light and heavy work

The starting values widely used in the ergonomics literature divide the working point for standing work into three groups relative to elbow height:

These values are a starting point, not strict limits. If the work requires close visual tracking, the height increases; if a large, heavy part is to be turned by hand, it decreases. The real message of the table is this: a single bench height does not suit all jobs. In a workshop where the quality control table and the deburring bench are at the same height, one of the two jobs is certainly at the wrong height.

The same logic applies to seated work, but the reference is the elbow height, which varies with seat height. There must also be enough clearance under the table for knees and legs; a cabinet or crate placed under the table forces the worker to lean forward.

Reach distance and work zones

The second measurement, as important as height, is how far the worker reaches for parts and tools. Think of the work area as three zones:

• Primary zone: The area reached by moving only the forearm while the upper arm stays beside the body. The most frequently picked parts and most used tools go here.
• Secondary zone: The area reached by extending the arm forward without bending the trunk. Suitable for occasionally used parts and tools.
• Outside the zones: The area that requires bending the trunk forward, twisting or reaching above the shoulder. This is the place for shelves, rarely used materials and stock boxes; it should not be used in cyclical work.

Reach distance is set according to the worker with short arms who will use the workstation: if someone with short arms can reach comfortably, someone with long arms can too. Clearances such as knee space and passage width are set according to the largest worker. The only dimension that usually needs to be adjustable is height.

Adjustable workstations for workers of different heights

On a line working shifts, three different people may use the same workstation. In that case a fixed height will at best suit the person of average height. Let us look at an example:

The suitable bench height ranges for the two operators do not overlap; there is a difference of at least 9 cm between them. A fixed 82 cm bench forces A to raise their shoulders and B to lean forward. The solution options are:

1. Height-adjustable bench: The electric or mechanical adjustment should be wide enough to cover at least these two ranges. To make adjustment easy at shift change, a mark showing each operator's setting can be placed on the bench.
2. Adjustable fixture: The bench stays fixed and the height or angle of the fixture holding the part is changed. In precision work with small parts, this is often the most economical route.
3. Platform: The bench is set for the taller operator and a sturdy platform is used for the shorter operator. The platform should cover the whole working area and have clearly marked, non-slip edges; otherwise it creates a trip and fall risk.

When buying an ergonomic bench, do not look only at the adjustment range: how easily it is adjusted, whether the bench wobbles under load, the risk of hands and feet being trapped during adjustment, and whether the cables of equipment on the bench have enough slack across the adjustment range also matter.

When measuring elbow height, measure the worker wearing their safety shoes, standing upright with relaxed shoulders; the shoe sole and posture change the result by a few centimetres. Measure not just one person but all workers who use the workstation, and write the values on the workstation card.

In work requiring force, lifting the part and placing it on the bench should also be assessed. When the bench height is adjusted, the lifting distance also changes; for lifting aids with heavy parts, see our article on manual handling and lifting technique.

Standing, sitting or sit-stand?

The working height decision cannot be made independently of working posture. A general distinction is:

• Seated work: Suitable for long, precise, small-part work requiring little force. The feet must rest on the floor or a footrest.
• Standing work: Suitable for work requiring force, large movements or frequent changes of position. For the strain of standing in the same spot for long periods, see our article on the risks of standing work.
• Sit-stand: At workstations where both types of work are mixed, high stools or lean supports allow the worker to change posture during the day.

Workstation checklist for metal and machine workshops

When reviewing workstations in metal and machinery businesses, ask the following questions:

• Are the jaws of the bench vice around the elbow height of the worker doing filing and deburring?
• Is the quality control and measuring table higher than the assembly bench, and can the elbow be supported while measuring?
• When loading parts into a CNC machine, is the clamping point above the shoulder or below the knee?
• Are frequently used hand tools on hooks or holders in the primary zone?
• Are parts boxes tilted forward and close to the worker; is bending needed to reach the part at the bottom of the box?
• Is there an adjustment option for the height difference between workers sharing the same workstation?
• If a platform is used, is it sturdy, non-slip and edge-marked?
• Is the screen or work instruction at eye level and at a readable distance?

For workstations where the checklist reveals a problem, the next step is an ergonomic risk analysis of the job. On lines with intensive repetitive movements, methods such as REBA and RULA show the priority of corrections in numbers. For the particular case of conveyor lines, see our article on repetitive movements and conveyor lines.

Common mistakes

• Measuring the bench surface: Not taking the height of the fixture or part into account.
• One standard for the whole factory: Ordering all workstations at the same height.
• Designing for the average worker: A workstation set up for the average may suit neither short nor tall workers.
• Never adjusting the adjustable bench: An operator who does not know where the adjustment button is, or has no time to adjust it, uses an adjustable bench like a fixed one.
• Waiting for complaints: Musculoskeletal complaints appear over years. A correction made at the design stage is much cheaper than one made later. On this topic, see our article on preventing musculoskeletal disorders.

When a new line is set up or a workstation changes, the risk assessment also needs to be reviewed. In production plants in Bursa and neighbouring provinces, we measure workstation dimensions and assess ergonomic risks on site as part of our risk assessment service. You can track revision dates with the OHS calendar.

Frequently Asked Questions

How high should a bench for standing work be?

There is no single correct value. The working point is set by the elbow height of the person doing the work: slightly above the elbow for precision work, 10–15 cm below it for light assembly, and lower still for work requiring force. The bench height is found by subtracting the height of the part or fixture from this point.

How is reach distance determined?

Frequently used parts are placed in the area reached with the forearm while the upper arm is beside the body; occasionally used ones in the area reached by extending the arm without bending the trunk. The distance is chosen for the worker with the shortest arms who will use the workstation.

Is an adjustable work table needed at every workstation?

No. If a single worker uses the workstation, a fixed bench can be set for that person. Where several workers of different heights share the same workstation, an adjustable bench, adjustable fixture or platform is needed.

Is workstation design part of the risk assessment?

Yes. Working posture, reaching and repetitive movements are ergonomic hazards and are addressed in the risk assessment. Workstation changes that amount to a change in equipment or production method require the assessment to be updated.