Question 2 of 7: Hazard-Control Priorities, Safety Devices, and Accident Investigation

Question 2: Hazard-Control Priorities, Safety Devices, and Accident Investigation (20 marks: 7/6/7)

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.

(i) Principles and Priorities of Hazard Control (Hierarchy)

1. Elimination — remove the hazard entirely.
2. Substitution — replace with a less hazardous material, process or equipment.
3. Engineering controls — guarding, enclosure, interlocks, ventilation, isolation.
4. Administrative controls — safe work procedures, training, rotation, signage, permits.
5. Personal protective equipment (PPE) — the last line of defence.

Priorities. Control at source, as close to elimination as practicable, before relying on the path or on the worker; the higher levels do not depend on human behaviour and so remain effective when attention lapses, whereas administrative controls and PPE fail whenever a worker forgets, misuses or removes them. Combine controls where one level cannot reduce the risk to an acceptable level on its own.

(ii) Purpose and Examples of Safety Devices

• Purpose — prevent contact with, stop, or warn of a hazard automatically. Examples: interlocks, presence-sensing devices (light curtains, mats), two-hand controls/trips, emergency stops, pressure-relief/safety valves, rupture discs, limit switches, guards, warning alarms/lights.

(iii) Accident-Investigation Steps and Tools

Steps: (1) respond/secure the scene; (2) gather facts; (3) interview witnesses separately; (4) analyze (immediate and root causes); (5) develop conclusions/corrective actions; (6) report, implement, follow up.

Tools/equipment: camera/video, measuring tape/laser, sketching tools, sample/evidence containers and bags, PPE, forms/checklists, barrier tape/tags, flashlight, and testing instruments (gas detector, multimeter) as relevant.