Reach and Limitation of Human:
In many work situations, individuals perform their activity within a specified 3D space of fixed location which is sometimes referred to as ‘work-space envelope’ (Sanders and McCormick 1993). This envelope preferably should be circumscribed by the functional arm reach of the operator and most of the things they need to handle should be arranged within this envelope.

In fig. 16 describe human capabilities and limits in terms of reach on horizontal work-surface with their measurements.


Fig. 16. Normal and maximum horizontal reach areas
(Image Source: Sanders and McCormick 1993).

Normal and maximum horizontal arm reach do not correlate with reach capabilities in actual vehicle workstations. Factors such as seat position, seat deflection, shoulder articulation, and lean allowed by slack in a shoulder harness (if one is worn) affect a driver’s reach capabilities.

Forward arm reach of the driver according to anthropometry  and seat track travel as described in SAE J287 shown in fig. 17.


Fig. 17. SAE recommended occupant packaging
(Image Source: Peacock and Karwowski,1993)