Cranes have capacity limitations unlike most other pieces of construction equipment. If a bulldozer attempts to push too much dirt, usually nothing bad happens. The equipment merely bogs down. Nothing breaks, and no one gets hurt. To recover, the operator merely backs up a bit, raises the blade and pushes on. If a crane exceeds its capacity limitations, there is usually a significant accident.

More than most pieces of equipment, gravity is working to collapse the equipment or cause the crane's load to fall to the ground. If the crane does not overturn, a structural failure could occur, with similar damage and results. Contrary to some conceptions, the design safety factor applied to cranes is quite small. Exceeding the structural or tipping capacity of a crane by even a modest amount can cause a serious accident.

A common misconception is that heavy loads cause most of the crane accidents. In many cases, light loads, or no load at all cause cranes to have tipping or structural failures. Crane accidents have occurred with some frequency since the invention of lifting machinery. Recent accidents that have involved the loss of lives have focused industry attention on cranes. Contrary to popular belief, there is no central repository of crane loss data. US crane accidents that cause a loss of life to workers, or injuries to multiple workers and lost workday cases must be reported to OSHA. Other than that, and a few local ordinances, most accidents are not reported. Many crane operators carry large insurance deductibles. Smaller losses may not be reported to insurance carriers. There has been some discussion about national loss reporting requirements, but workable solutions are not imminent.

There are three basic types of crane accidents:

  • Structural failure

  • Tip-over

  • Collision

The basic causes of crane accidents are one or more of the following categories:

  • Operations

  • Assembly/disassembly

  • Rigging

  • Maintenance

  • Weather

Other fringe causes exist, including design, vandalism, faulty repairs or counterfeit parts. Most of these could be included in the operations or maintenance categories above. Firm data is not available to put numerical values on the accident cause categories. Nearly all agree that operations represent well over half of the losses.

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