Adequate ground conditions are essential for safe crane operations because the crane's capacity and stability depend on such conditions being present. If, for example, the ground is muddy or otherwise unstable, a crane could overturn even if operated with the load limits specified by the manufacturer.
BASIC RULE (short version): You must not assemble or use a crane, unless the equipment manufacturer’s specifications for adequate support and degree of level of equipment are met.
BASIC RULE (long version): You must not assemble or use a crane unless ground conditions are firm, drained, and graded to a sufficient extent so that, in conjunction (if necessary) with the use of supporting materials (such as blocking, mats, cribbing, or marsh buggies (in marshes/wetlands), the equipment manufacturer's specifications for adequate support and degree of level of the equipment are met. The requirement for the ground to be drained does not apply to marshes/wetlands.
A contractor operating a crane on a construction site may not have the ability or authority to provide for adequate ground conditions at the site. The standard, therefore, places the responsibility for ensuring that the ground conditions are adequate on the "controlling entity" at the site. The “controlling entity” is the prime contractor, general contractor, construction manager, or other legal entity with overall responsibility for the project's planning, quality, and completion.
The controlling entity must also inform the user and operator of the equipment:
If there is no controlling entity for the project, the responsibility for providing adequate ground conditions rests on the employer that has authority at the site to make or arrange for ground preparations.
Although the controlling entity is responsible for providing adequate ground conditions, the company operating the crane will often be better able than the controlling entity to determine whether those conditions are adequate. If you are operating a crane and decide that ground conditions are inadequate, you must discuss the problem with the controlling entity and see that the problem is corrected before beginning or continuing operations.
Accidents during assembly and disassembly of lattice boom and tower cranes are one of the major causes of crane-related fatalities. These sections are designed to prevent such accidents by requiring safe assembly/disassembly procedures for lattice boom and tower cranes. Hydraulic-boom cranes are not generally assembled on-site, but these sections contain some provisions, such as the requirement (Standard 1404(q)) for proper setting of outriggers and stabilizers, which apply to cranes with hydraulic booms.
When assembling or disassembling a crane, you must comply with either manufacturer or employer procedures, which must be developed by a qualified person.
Such procedures must, at a minimum:
Regardless of which of these options you choose, you must follow any manufacturer prohibitions that apply to the assembly/disassembly operation.
All assembly/disassembly operations must be directed by an individual who meets the criteria for both a competent person and a qualified person, or by a competent person who is assisted by one or more qualified persons. The A/D director must understand the applicable assembly/disassembly procedures. The A/D director must take the following precautions to protect against potential hazards associated with the operation, including:
Before the operation begins, the A/D director must ensure that the crew members understand all of the following:
Before a crew member goes to a location that is out of view of the operator and is either in, on, or under the equipment, or near the equipment (or load) where the crew member could be injured by movement of the equipment (or load), the crew member must inform the operator that he/she is going to that location. Whenever the operator knows that a crew member is in such a potentially dangerous position, the operator must not move any part of the equipment (or load) until the operator is informed in accord with a pre-arranged system of communication that the crew member is in a safe position.
When rigging is used for assembly/disassembly, the employer must ensure that the rigging work is done by a rigger who meets the requirements as a qualified person and successfully demonstrates the ability to solve/resolve problems relating to rigging.
A rigger is required when:
A rigger doesn't have to be qualified to do all rigging jobs. You must determine whether a person is qualified to perform specific rigging tasks. Each qualified rigger may have different credentials or experience. (Oregon OSHA)
When pins (or similar devices) are being removed, employees must not be under the boom, jib, or other components, unless site constraints require one or more employees to be in such a position. In such a case, the A/D director must implement procedures that minimize the risk of unintended dangerous movement and minimize the duration and extent of exposure under the boom.
A crew of ironworkers and a crane operator were unloading a 20-ton steel slab from a low-boy trailer using a 50-ton crawler crane with a 90-foot lattice boom. The operator was inexperienced on this crane and did not know the length of the boom. Further, no one had determined the load radius. During lifting, the load moved forward and to the right, placing a twisting force on the boom. The boom twisted under the load, swinging down, under and to the right. Two crew members standing 30 feet away apparently saw the boom begin to swing, and ran. The boom struck one of the ironworkers in the head, causing instant death. Wire rope struck a management-trainee and caused internal injuries. He died two hours later at a local hospital.
When using synthetic slings during assembly or disassembly, you must follow the synthetic sling manufacturer's instructions, limitations, specifications and recommendations. Synthetic slings must be protected from abrasive, sharp or acute edges, and configurations that could cause a reduction of the sling's rated capacity, such as distortion or localized compression.
When outriggers or stabilizers are used:
The following precautions must be taken to prevent dangerous movement of boom and jib sections that are being dismantled.
During assembly/disassembly work, fall protection is generally required when a worker is more than 15 feet above an unprotected side or edge. See Standard 1423.
This is a a very informative video on crane safety developed by the Department of Defense.
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