Working deck at 3.0 m, no guardrail, pour at 4:00 p.m.
A six-man crew is setting formwork for the second-floor slab of a three-storey house. The slab soffit is 3.0 m above the ground floor, and the working deck is a steel scaffold frame carrying two 50 mm x 250 mm lumber planks laid side by side, overlapped only 150 mm and not cleated. The open edge facing the stairwell has no guardrail and no toeboard, and loose 2x3 offcuts and a claw hammer sit within 200 mm of that edge. Six full-body harnesses are in the toolbox, but there is no rated anchor point on the structure, and the helper proposes looping the lanyard around a 48 mm scaffold tube. A 20 m orange extension cord with a taped joint lies in a puddle left by curing. The ready-mix truck is booked for 4:00 p.m. and the foreman tells you to keep going so the pour is not delayed. You are the lead carpenter on the deck.
1. Identify the hazards in this setup and state exactly what you do in the first ten minutes on site.
Read the worked answer
Group the hazards rather than listing them randomly:
- Fall from height: open edge at 3.0 m with no guardrail or toeboard.
- Losing the working platform: planks overlapped 150 mm (below the usual 200 mm minimum), not cleated, unknown grade, no inspection.
- Falling objects: offcuts and a hammer at the edge, no toeboard, people working below.
- Electrical: damaged cord with a taped joint in standing water, no mention of RCD protection.
- Schedule pressure: the foreman's instruction is itself a hazard because it pushes the crew to skip controls.
In the first ten minutes: call a verbal stop on the deck, get all six off the planks, clear loose material from the edge, unplug the extension cord at the source and tag it out, and barricade the stairwell edge. Then report to the foreman and the safety officer in person, and follow with a written stop-work note.
Reasoning: none of these hazards are fixed by a reminder. The deck is not a workplace until it has edge protection, sound decking, housekeeping and safe power. Stopping early costs minutes; a fall from 3.0 m is a fatal or permanently disabling event, and the cost of a delayed truck is trivial beside that.
2. The helper argues that tying the lanyard around the scaffold tube is good enough. Explain why that is unsafe and what control should have been in place before anyone stood on the deck.
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Three separate problems:
- The anchor is not rated. A 48 mm tube in a scaffold frame is designed for scaffold loads, not for the arrest force of a falling body, which can far exceed body weight. It may slip at the coupler or deform. Anchors must be rated and engineered, not improvised.
- Geometry defeats the lanyard. Tied at foot level, the worker falls past the anchor before the lanyard loads, so free-fall distance plus swing into the frame or ground is likely. Swing and sharp edges then cause injury even if the arrest works.
- It is the wrong layer of control. Fall arrest is the last line of defence. The hierarchy runs: eliminate the need to work at the edge, then engineer the protection (guardrail, toeboard, properly designed and inspected scaffold with a competent-person check and tag), then administrative controls, then PPE.
So the correct answer is not a better tie-off point. The control that should have existed before first use is a complete edge-protection system plus a documented pre-use inspection. If harnesses are used at all, they need a rated anchor, a rescue plan, and an inspection record. Never let a crew member wear a harness that gives false confidence in an unguarded edge.
3. The foreman repeats the instruction. How do you respond, what do you record, and what must be true before the pour goes ahead?
Read the worked answer
Respond factually, not personally: state the specific deficiencies and that you are exercising stop-work authority, then offer options so the foreman is not cornered - pour a later bay, have the scaffold contractor finish the edge protection within the hour, or reschedule the truck. A short delay costs far less than an incident, and the supplier can usually re-slot a delivery.
Record as you go: time and date of the stop, the list of deficiencies, photographs, the name of the person you informed and their response, the toolbox talk attendance, and the corrective actions with times closed out. Escalate in writing to the safety officer and project manager if the instruction is repeated.
The pour can proceed only when: guardrails and toeboards are fixed on every open side including the stairwell; planks are proper scaffold boards, cleated and overlapped at least 200 mm; the deck has passed a competent-person inspection with a visible tag; the damaged cord is replaced and protected by an RCD; loose material is cleared; safe access for the crew and the vibrator hose exists; and the crew has been briefed. If any one of those is missing, the deck is not ready and the concrete waits.