“An excavation-collapse bowtie: the hazard is workers entering an excavation and the top event is an excavation wall collapse. Show unstable soil, spoil piles and water ingress as threats, with assessment, shoring, setbacks, inspection, dewatering and weather monitoring as barriers. Show entrapment, serious injury and worksite disruption with rescue, communication, medical response, scene control, stop-work and re-entry barriers.”
図の背後にある意思決定を読み解く。
Keep worker exposure in view.
State the wall collapse.
Include assessment, engineering and inspection.
Plan rescue and medical response.
Use in a pre-job safety discussion with site-specific competent-person requirements.
よくある質問
What is the top event?
The excavation wall collapse is the central loss of control in this example.
Why include a rescue plan?
Rescue is a recovery barrier that can reduce harm after a collapse.
Can weather be added?
Yes. Rain or water ingress can be modelled as a threat or escalation factor.