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.

OSHA's 1926.1425 prohibits employees in the fall zone while a load is suspended, except those hooking, unhooking or guiding the load, making initial connections or operating a concrete hopper, and then only if the load is rigged to prevent displacement, hooks have closed latches and a qualified rigger rigged it. The fall zone is defined in 1926.1401 as the area, including but not limited to the area directly beneath the load, in which it is reasonably foreseeable that partially or completely suspended materials could fall in the event of an accident. Under 1926.1424, the area within the swing radius of the rotating superstructure must be barricaded or marked when it creates a struck-by or crushing hazard.

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-story 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 meters 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 practiced. 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

OSHA's 1904.39 requires employers to report a work-related fatality within 8 hours, and an in-patient hospitalization, amputation or loss of an eye within 24 hours. Many state plans have similar or stricter rules. Crane collapses and dropped loads often draw OSHA inspections even without serious injury, and owners, insurers and crane rental companies usually require prompt incident reports.

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.