23-Ind-B5 Ergonomics · December 2014
Nivaar worked solution (AI-drafted; not reviewed by a licensed engineer)
National Exams — Dec. 2014 — 98-Ind-B5 Ergonomics. Three-hour, open-book exam (all notes, books and any non-communicating calculator permitted); the paper requires 4 of its 5 questions (Part A mandatory, any two of Part B's Questions 2–4, and Part C mandatory) — all five are solved below for completeness.
Reference texts: Sanders & McCormick, Human Factors in Engineering and Design (7th ed.) — controls/displays, anthropometry, workplace and computer-workstation design; Waters, Putz-Anderson & Garg, NIOSH Applications Manual for the Revised NIOSH Lifting Equation (1994) — the RWL/LI formula and multiplier tables reproduced on the exam's own pages 6–7; NIOSH, Elements of Ergonomics Programs (1997) and CSA Z1004 (Canada) — workplace musculoskeletal-disorder (MSD) prevention programs.
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.
A task analysis breaks the purchase into the sequential actions a user performs and the decisions embedded in each. The typical task sequence is: (1) approach the machine and read the idle-screen prompt; (2) select the ticket class – ride-any-time, zone-based, or single-mode/single-zone – the first and most consequential decision, since it determines every downstream screen; (3) if ride-any-time is chosen, select the duration (daily/weekly/monthly); (4) if zone-based is chosen, select the origin and destination zone(s) (1 of 3, with the system computing the price from the number of zone boundaries crossed); (5) if single-mode/single-zone is chosen, select the specific transportation mode (bus, streetcar, subway, intercity rail); (6) select the quantity of tickets, if more than one is being purchased in the same transaction; (7) review the displayed price and confirm, or cancel and restart; (8) select a payment method (credit, debit, or cash); (9) complete the payment action (insert/tap card, enter PIN, or insert cash/coins); (10) retrieve the card (if used) and any change; and (11) retrieve the printed bar-coded ticket and any receipt.
The decisions a purchaser must make therefore fall into five categories: which ticket class (the root decision, driving flexibility vs. cost), which duration/zones/mode (conditional on the class chosen), how many tickets, how to pay, and whether to confirm or cancel at the price-review step. A well-designed interface makes the root decision (ticket class) the very first control the user sees, since every later screen and control depends on it.
The panel is organized top-to-bottom in the same order the task analysis in part (a) exposes: display first, then the ticket-class/zone/duration decision controls, then payment, with a dedicated accessibility cluster and a distinct cancel/help control available at every step.
Each design decision is justified against a specific human-factors principle:
Grouping and sequence (task-flow compatibility). Controls are laid out top-to-bottom to mirror the exact task sequence identified in part (a) – class, then zone/duration, then payment, then dispensing – so the panel itself teaches the procedure and the user is never asked to look for a control out of the order they expect to use it. Functionally related controls (all three payment methods; the accessibility cluster) are physically grouped, per the proximity-compatibility principle.
Pictogram + text labelling. The three ticket-class keys use large pictograms (a padlock/globe icon for ride-any-time, a concentric-zone icon for zone fare, a single-bus icon for one-way) paired with short text in the two most common local languages, so the machine is usable without relying on reading ability alone – important given the population range noted below.
Control-display compatibility and Fitts's law. Each physical key's position corresponds spatially to the option it produces on the display directly above it, so the mapping is unambiguous (a stereotype users transfer instantly from other kiosk-style machines). Because ticket-class selection is the highest-frequency, first-touched control, its keys are made the largest on the panel and placed at the most comfortable reach distance (roughly 700–1100 mm above standing floor level) – a direct application of Fitts's law (larger targets at shorter, more direct reach distances are faster and less error-prone to acquire).
Population stereotypes and coding. The Cancel/Help key is coded red and physically isolated from the numeric/selection keys, matching the near-universal population stereotype that red means "stop/abort" and preventing an accidental cancel from being mistaken for a normal selection key. Confirm actions use a green accent, consistent with the same stereotype. Colour coding is never used as the sole cue, however (see colour-vision accommodation below) – every colour-coded control also carries a distinct icon/shape and text label.
Tactile/auditory redundancy for low-vision and blind users. The accessibility cluster provides a physically distinct, Braille-labelled keypad with tactile detents (so keys can be located and confirmed by touch alone) and a 3.5 mm audio jack for a synthesized-voice walkthrough of every screen, so a blind or low-vision user can complete the same task sequence as a sighted user without needing to read the display.
Payment control types. The tap pad uses a large (≥80 mm) flush contactless target with an audible/visual confirmation tone (fast, low dexterity demand, and works for riders who cannot easily manipulate small buttons); the card slot has a bevelled, self-orienting insertion guide (reduces insertion errors and required fine motor control versus, e.g., a small turning knob); the cash/coin slot accepts bills face-up in either orientation and provides a lit "insert here" indicator, since orientation ambiguity is a leading source of user error on cash-accepting kiosks.
Legibility and glare. The display uses a minimum 3–5 mm character height for the intended 0.5–1 m viewing distance, high luminance contrast (dark text on light background per WCAG-style guidance), and an anti-glare/matte screen finish, since transit kiosks are frequently used outdoors or under mixed lighting.
Population demographics accommodated. The panel is designed to accommodate the full range of transit riders, not a single "average" user: (1) stature/reach – the primary control cluster sits within the functional reach envelope of a 5th-percentile female standing and a wheelchair-seated user simultaneously (controls kept below ~1100 mm, with the highest-priority ticket-class keys lowest in that band), up to a 95th-percentile male; (2) sensory ability – the tactile/Braille/audio cluster serves blind and low-vision users, and no information is conveyed by colour alone (serves colour-vision-deficient users); (3) motor ability – large, well-separated keys and a self-orienting card slot reduce the fine-motor and grip-force demand for older adults or users with limited hand dexterity, and the tap-pad payment option requires no grasping motion at all; (4) language and literacy – pictogram-first labelling and a selectable-language text layer serve non-native speakers and visitors; (5) experience level – the task-flow-ordered layout and on-screen prompts are designed so a first-time user can complete a purchase unaided, while the same layout does not slow down a frequent commuter who already knows the sequence.
