Exclusion zones, site coordination and emergency response

Lesson 1 showed that more than half of crane deaths involve workers struck by objects or equipment. Most of those workers were not operating the crane. They were walking past, working below, standing near the counterweight or guiding a load from too close. Exclusion zones keep people out of the places where a lift can hurt them, site coordination keeps lifts from colliding with other work, and emergency planning makes sure that when something does go wrong, the response does not make it worse.

The zones around a lift

Several overlapping zones surround every crane lift. Each needs its own control.

• The fall zone is the area where a load or part of it could land if it slipped, broke free or the crane failed. It includes the area directly under the load and extends beyond it, because falling loads can drift, tumble, slide or scatter debris.
• The counterweight or tail swing zone is the area swept by the rotating upperworks of the crane. Anyone caught between the counterweight and a fixed object can be crushed.
• The landing zone is where the load will be set down. Only the workers needed to receive and land the load may be there, and only when the load is close to landing.
• The outrigger and track areas can be hazardous if a float settles or a beam moves.
• Power line zones are covered in Lesson 9.

Canadian rules generally prohibit moving loads over workers where it can be avoided and require that workers not stand or pass under a suspended load. Alberta's section 69 says lift planning must ensure, wherever possible, that loads are not moved over workers, and that workers who must be nearby are warned. Ontario's construction regulation requires that loads not pass over workers and that areas where workers could be endangered be controlled.

Sizing and marking the fall zone

There is no single formula for the size of a fall zone. It depends on the load's size, height, shape and the way it might fail. A compact steel casting dropped from a low height lands nearly straight below. A sheet of plywood, a bundle of pipe or a panel lifted high in wind can glide or scatter well beyond its footprint. Good practice is to mark a zone that covers the load path with a generous margin on each side, and to make it larger for higher lifts, lighter flat loads and windy conditions.

Fall zones are marked with barricades, fencing, warning tape, cones and signs, and enforced by a person whose job is to keep people out. On multi-storey buildings, floors below a load path may need to be cleared, and work under a tower crane's regular routes may need overhead protection or rescheduling. Where a load must pass over an occupied area, such as a lift over an operating plant, the plan should say how people will be moved, warned or protected for the duration.

The counterweight swing zone

A rotating crane's counterweight can crush a person against a truck, a wall, a scaffold or another machine. Operators usually cannot see behind the crane while swinging. The zone is controlled by barricading it so nobody can walk in, with the barricade placed far enough from the counterweight that a person standing at it cannot be reached.

Site coordination

On a busy site, a crane is one activity among many. Lifts need to be scheduled so that other trades know when areas will be closed, deliveries arrive when the crane and crew are ready, and loads do not travel over workers on scaffolds or roofs. A daily lift schedule, a crane coordination meeting and a single person responsible for crane priorities help prevent conflicts.

Work above other work is a recurring problem. A crane setting roof trusses over a floor where electricians are working, or a tower crane flying rebar bundles over a busy deck, puts people in the fall zone for hours at a time. The answer is usually scheduling, rerouting the load path or clearing the area below, not asking workers to watch out.

Emergency planning

Every lift plan should include what to do if something goes wrong, and critical lifts should have a specific emergency section. The crew should talk through the most likely emergencies at the pre-lift meeting so that everyone knows their part before it is needed.

Tower crane operators work in cabs tens of metres above the ground. If an operator becomes ill or injured, getting them down requires trained rescuers, rope rescue equipment and a plan that has been practised. Local fire services may or may not have high-angle rescue teams that can respond quickly; the employer must find out and plan accordingly before the crane is erected.

Reporting and investigation

In Ontario, the Occupational Health and Safety Act requires immediate notice to the Ministry of Labour, Immigration, Training and Skills Development of a death or critical injury, with a written report within 48 hours, and the scene must not be disturbed except to save life, relieve suffering or prevent further damage. The Act and the construction regulation also require notice of certain incidents even when nobody is hurt, such as the collapse or failure of a crane or hoisting device; check the current list in the regulation. Other provinces have similar rules.

Every crane incident and near miss should be investigated to find root causes, not just the immediate trigger. A dropped load may trace back to a missing weight on a shipping document, a sling that should have been retired months ago or a schedule that pushed the crew to lift in rising wind. The investigation methods in HSE-103 apply: gather facts, preserve evidence such as the load moment indicator data log and the failed rigging, interview witnesses, and identify the system failures behind the event.