Crane, Rigging, Equipment, and Struck-By Case Lab

Crane, Rigging, Equipment, and Struck-By Case Lab

Scenario

A mechanical contractor is preparing to set an air handling unit on a roof using a mobile crane. The unit arrived late, so the lift is being moved into the afternoon while concrete trucks, telehandlers, and roofing crews remain active nearby. The crane pad was placed over a recently backfilled utility trench. The rigging crew has a spreader bar, synthetic slings, and shackles, but one sling label is unreadable and sharp metal edges are visible on the load frame. The operator asks for a clear signal person because two supervisors are giving hand signals from different sides of the building.

First Priorities

The CHST should focus on preventing high-energy struck-by and crush exposures. The lift should not proceed until the lift director or responsible competent person confirms the plan, ground conditions, rigging, communication, and exclusion zones. Multiple signal persons giving conflicting directions is an immediate stop-work issue. So is a suspended load path over workers or active traffic. The unreadable sling label and unprotected sharp edges also require correction before use.

A practical sequence is:

1. Pause the lift and keep the load on the ground.
2. Establish and enforce the swing radius, load path, and landing area exclusion zones.
3. Confirm one designated signal person, communication method, and stop signal authority.
4. Verify load weight, crane configuration, radius, capacity, ground support, and weather limits.
5. Inspect rigging and replace or remove questionable components.

Lift Planning and Ground Conditions

The crane may have enough chart capacity and still be unsafe if the setup surface cannot support the load. Recently backfilled trenches, voids, underground utilities, soft soil, and slopes can undermine outrigger support. The plan should verify soil or matting requirements, outrigger extension, cribbing, level setup, and access path. If the crane pad crosses a utility trench, engineering or competent evaluation may be needed before continuing.

Rigging and Equipment Controls

Rigging selection is not guesswork. Slings, shackles, hooks, and spreader bars must be rated, inspected, and compatible with hitch type and load geometry. Synthetic slings need protection from sharp edges and heat. Missing or unreadable identification prevents reliable capacity verification and should remove the sling from service until evaluated according to the employer procedure. A qualified rigger should know sling angles, center of gravity, load control, tag line use, and when a trial lift is needed.

Equipment traffic also matters. Concrete trucks, telehandlers, delivery vehicles, and pedestrians should not share an uncontrolled route with crane setup or landing activities. Backing alarms, spotters, barricades, haul road planning, and high-visibility clothing are helpful, but they do not replace physical separation where feasible.

Emergency and Incident Response

A lift plan should include what happens if wind increases, communication fails, power lines are approached, a load shifts, equipment contacts a structure, or a person enters the exclusion zone. Everyone needs authority to give an emergency stop signal. If a load is dropped or a struck-by incident occurs, preserve the scene when life safety allows, secure the equipment, call emergency services as needed, and prevent restart until the incident is investigated.

The CHST should resist the urge to solve a near miss by telling workers to be more careful. If two supervisors gave conflicting signals, that is a leadership and planning failure. If the load path crossed active work, that is a coordination failure. If rigging was not identifiable, that is an inspection and procurement failure.

Communication and Documentation

The pre-lift meeting should be brief but specific. Cover load weight, pick and set points, crane configuration, roles, signal method, exclusion zone boundaries, weather stop criteria, tag line use, emergency stop, and what work must pause nearby. Subcontractors affected by the lift need the same information, not just the rigging crew.

Document the final lift plan, JHA, rigging inspection, crane setup verification, affected crew notification, and any stop-work decision. If the lift is delayed, restart planning should consider changed conditions: wind, lighting, fatigue, traffic, ground disturbance, or revised load path. On the exam, the best answer usually keeps people out of the line of fire, confirms qualified roles, and verifies capacity and communication before production continues.