23-Ind-B6 Human Factor in Design · May 2013
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Examinations, May 2013 — 98-Ind-B6, Workplace Design (3-hour closed-book exam, Casio/Sharp approved calculators only. The front page states any 5 of the 7 questions, each worth 20 marks, constitute a complete paper; all 7 are answered below.)
Reference texts: Sanders & McCormick, Human Factors in Engineering and Design (7th ed.) — controls and displays, anthropometry and workstation design, physical work and manual materials handling, and human-machine system arrangement; Niebel & Freivalds, Methods, Standards, and Work Design — workplace layout and posture.
Question text not reproduced: the examination questions are © Engineers and Geoscientists BC. Open the official past paper (linked at the top of this page) to read the question, then follow the worked solution below.
Component arrangement follows the same importance/frequency/function/sequence hierarchy already introduced for displays-and-controls and individual-workplace layout (Q2(iii), Q5(i)), now applied at the scale of a whole facility, control room, or work cell: importance — place the components most critical to safe or successful operation where they are most visible/accessible; frequency of use — place the most frequently used components (or the components with the highest interaction/link value, part iii) in the most convenient positions; functional grouping — cluster components that serve a related function; and sequence of use — arrange components used in a fixed operating order to match that order spatially, minimizing backtracking. The overriding goal in every case is to minimize the total travel, search, and reach effort summed across all the interactions the arrangement must support.
A "link" in link analysis is any interaction (a movement, a communication, a sight-line) between two components, and links are classified by what the two linked components are: person-to-machine (or person-to-equipment) links — an operator viewing a display or operating a control, the classic control-response link of Q1(iii); person-to-person links — verbal, visual, or physical communication/hand-off between two operators or between an operator and a supervisor; and machine-to-machine (equipment-to-equipment) links — a material or signal flow directly between two pieces of equipment with no person mediating the transfer (e.g., a conveyor feeding one machine's output directly into the next). A real workplace/system almost always contains all three classes simultaneously, and link analysis (part iii) treats them together on a single diagram so the resulting layout is optimized across all interaction types at once, not just the person-machine ones. Links are also classified by the kind of interaction they carry: communication links — visual (reading a display, seeing another person), auditory (voice or non-voice signals) and touch; control links — an operator acting on equipment through a control (hand or foot operation); and movement links — sequential eye, hand or whole-body movements from one component to another. Recording both the component pair and the link type lets the analyst weight and draw each link appropriately.
Link analysis lays out equipment and personnel positions to minimize the cost (distance, time, or difficulty) of the interactions the system actually requires, following four steps: (1) identify every link between every pair of components (people and/or machines) in the system — every sightline, communication, and material/movement path; (2) rate each link's importance, typically by observed or estimated frequency (trips or communications per shift) and by criticality (a safety-critical link is weighted up even if infrequent); (3) construct a link diagram — a node for each component, connected by a line for each link, with line thickness or an attached numeral representing the link's rated value; and (4) iterate the physical arrangement — reposition the nodes so that components joined by the highest-value links sit closest together, subject to any fixed constraints (a machine bolted to the floor, a required safety clearance), and re-draw the diagram after each trial to confirm total weighted link-distance has fallen. Conventional symbols make the diagram readable at a glance: a circle for each person, a square for each item of equipment or work location, a connecting line for each link, and the link value written on (or encoded by the thickness of) that line; line style can additionally distinguish link types (e.g., solid for movement/control links, dashed for voice communication).
Reading the figure as a worked example: the Operator node sits directly between Machine A and Machine B because those two links (8 and 7) are its highest-value links, while the low-value Operator–Inspection link (1) is left as the longest path in the arrangement — link analysis accepts a long low-value link in exchange for shortening the high-value ones, since total weighted travel is what the procedure minimizes, not the length of any single link.
