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, job rotation, training, signage, permits.
5. Personal protective equipment — the last line of defence.

Principle: control the hazard at source and as close to elimination as practicable; higher levels are preferred because they do not depend on human behaviour.

(ii) Purpose and Examples of Safety Devices

• Purpose — prevent contact with, stop, or warn of a hazard automatically, without relying solely on the worker.
• Examples: interlocks, presence-sensing devices (light curtains, mats), two-hand controls/trips, emergency stops, pressure-relief/safety valves, rupture discs, limit switches, guards, and warning alarms/lights.

(iii) Accident-Investigation Steps and Tools

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

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