5.4 Workstation Design and Computer Work

Workstation Fit And Task Design

A workstation should fit the work and the workers who perform it. The goal is not one frozen 'perfect' posture; it is a layout that allows neutral positions, variation, appropriate force, clear visibility, and efficient movement without repeated extreme reach or sustained static loading.

Anthropometry — The Design Math

Anthropometry is the study of human body dimensions. The exam-critical principle is that workers vary, so you design to percentiles from tables (e.g., NASA/military anthropometric data):

• Clearance dimensions (doorways, legroom, escape openings) are designed to the 95th percentile male so the largest users fit.
• Reach dimensions (control placement, shelf height) are designed to the 5th percentile female so the smallest users can reach.
• Adjustable dimensions (chair, desk, monitor) should span roughly the 5th-percentile female to 95th-percentile male so ~90% of users fit.

A station built for the 'average' worker fits almost nobody — it forces shoulder elevation for a shorter person and trunk flexion for a taller one. Adjustable surfaces, footrests, movable fixtures, and flexible parts presentation absorb that mismatch.

Computer (VDT) Workstation Targets

Computer work is the most-tested workstation example. Aim for neutral posture:

• Monitor: top of screen at or just below eye level; viewing distance about an arm's length (20–40 in); tilted slightly back; positioned to avoid window/overhead glare.
• Elbows: bent about 90–110°, upper arms relaxed near the torso.
• Wrists: straight/neutral over the keyboard and mouse — no extension or ulnar deviation; mouse beside the keyboard at the same height.
• Seat: thighs roughly horizontal, ~2–3 fingers' clearance behind the knee, lumbar support engaged; feet flat or on a footrest.
• Work-rest: micro-breaks and posture changes to break up static loading; the chair is support, not a cure for a bad desk, monitor, or workload.

Standing And Sequencing

Standing stations need the same analysis: provide a foot rail, anti-fatigue mat, appropriate height, and room to shift posture — mats do not excuse poor reach or long static stance. Sequence parts in the order used; keep heavy/frequent items near the body between knee and shoulder height. Precision tasks need support and visibility; forceful tasks need a stable body position and often a lower work height than fine assembly.

The classic trap is choosing adjustability without implementation. An adjustable station helps only if workers know how to adjust it, supervisors allow the time, and maintenance keeps it working. Verify use in the field and remove the barriers. The best answer changes layout, equipment, or method so the job needs less reach, less force, and more variation — then trains workers to use it.

Reach Zones And The Design Envelope

Designers divide the bench into reach zones drawn from arm length. The primary (normal) work zone is the area swept by the forearm with the upper arm at the side — the most-used tools and parts live here. The secondary (maximum) work zone is swept with the arm extended and is reserved for occasional items. Anything beyond the maximum zone forces trunk flexion, shoulder elevation, or stepping, all of which add posture and static load. A useful exam heuristic: if a worker must lean, twist, or stretch on every cycle to reach a component, the layout — not the worker — is wrong.

Lighting, Glare, And Visual Demands

Visual demand drives posture more than candidates expect: workers crane and lean to see. Provide illumination matched to the task — roughly 300–500 lux for general office and assembly work and more for fine inspection — and control glare with indirect lighting, matte finishes, shades, and proper monitor placement. Position labels and displays inside the normal line of sight (about 15° below horizontal for seated work) so the neck stays neutral. A magnifier or task light often beats redesigning the whole station when the only problem is that the worker cannot see the part.

Sit-Stand And Remote/Field Work

The ASP11 blueprint explicitly lists in-office, remote, field, assembly, and bench/hood settings. Sit-stand desks reduce prolonged static sitting, but only if the worker actually alternates and the monitor and keyboard move with the surface. Remote workers improvising at a kitchen table need the same neutral-posture targets achieved with low-cost aids — an external keyboard and mouse, a laptop riser or stacked books, and a supportive chair with a footrest. Field and vehicle-based work adds whole-body vibration and confined postures that a fixed-office checklist misses, so the assessment method must follow the work, not the building.