Federal OSHA and ANSI standards address elevating work platforms in two different  ways.  Scissor lifts are considered mobile scaffolds and are subject to the requirements of 1926.452(w), 1926.451(g)(1) and ANSI A92.3 and A92.5.  Articulating and extensible platforms (e.g. bucket trucks and booms) are subject to the requirements of 1926.453 and ANSI A92.2and A92.5.

Federal standards for elevating work platforms are not clearly written and may be confusing.  ANSI standards are included only by reference, not as full text. It is more efficient to refer to one of the state standards, such as Washington's, which are more clearly written, more complete, and at least as protective as the Federal standards. The equipment manufacturer's operations and maintenance manual is a required reference and must maintained on the equipment and must be read and adhered to by the operator.

Contractors should prepare and follow written maintenance, inspection, and operating procedures.  An excellent example is available from Lawrence Livermore Labs.

Contractors using aerial lift equipment must ensure that:

• The equipment that they buy, lease, rent or borrow is built and maintained in accordance with OSHA and ANSI requirements.
• Each piece of equipment is provided with an operation and maintenance manual that is maintained on that piece of equipment (not in the office)
• A qualified person effectively trains all equipment operators and that no untrained person is permitted to operate the equipment.
• The equipment is operated within the safe limits as specified by the manufacturer and that any provided stabalizing devices, such as outriggers, are used in accordance with the manufacturer's instructions.
• Guardrails are kept completely in place, including entry opening chains or gates.
• The equipment is kept clear of electrical sources.
• All workers in boom and bucket lifts properly wear and attach fall arrest systems. (Workers on guarded scissor lifts are not required to use personal fall arrest systems unless they leave the lift's guarded area.
• A thorough equipment and work area inspection is conducted prior to using each lift. 

Operators (workers) using aerial lift equipment must

• Be trained by a qualified person before operating any lift
• Read, understand and follow the manufacture's operating instructions for the specific piece of equipment being used
• Read all decals, warning and instructions on the work platform
• On a daily basis, before the work platform is used, check for defects such as cracked welds, hydraulic leaks, damaged  control cables, loose wire connections and tire damage and inspect functional controls for proper operation.

Before each elevation the operator must check:

• For overhead obstructions and high-voltage conductors. A minimum of ten feet must be maintained at all times between any conductor and the operator and work platform  It is recommended that this distance be marked on the ground to aide operators.
• That the platform is elevated only on a firm and level surface (unless the equipment is specifically designed for unlevel surfaces, in which case the manufacturer's directions must be strictly followed).
• That the load is configured on the platform in conformance with the manufacturer's recommended load limits
• That any required outriggers or stabalizers are deployed
• That guardrails are installed and that entry gates or chains are securely closed
• For boom and bucket trucks, that all occupants are wearing properly attached full-body harnesses.

While driving the elevating work platform (under the conditions specified by the manufacturer) the operator must:

• Look in the direction of travel
• ensure that the path is clear, firm, and level
• maintain a safe distance from obstacles, drop-offs, holes, personnel and other hazards.
• maintain a safe distance from overhead obstacles
• maintain a safe speed

Tip-Over Prevention

Scissor lifts, like other scaffolds, must be maintained in a level and plumb configuration.  Indoor or "slab" machines are required by ANSI to be tested for stability at 5 degrees greater slope than the machine is rated for. Manufacturers, however, usually treat this as a safety margin and clearly mark the equipment for use on level surfaces only. These lifts must not be used on uneven surfaces or where they may be driven into holes or depressions greater that 4 inches.  Scissor lifts specifically designed for rough terrain are available.  Any outrigger or stabilizing device provided by the manufacturer must be used in strict compliance with the operations manual. No exceptions may be made for brief jobs.

Fall Prevention 

Either a guardrail or a personal fall arrest system must be used by workers on a scissor lift. A properly maintained and closed guardrail system best serves this purpose. Attachment points may be provided for lanyards, but should only be used for fall restraint since fall arrest could cause the lift to tip over if the lift has not been specifically designed to accomodate the resultant force. Although a body belt may be used for a fall restraint (not fall arrest) system, it is better practice to use a full body harness.

A fall arrest system may be required if the worker exits the guarded area of the scissor lift. In that case the lanyard must be attached to a suitable exterior attachment point, not to the guardrail.  Workers must not be attached to an external anchorage point while working on the lift. Workers in an aerial lift (boom or bucket truck) MUST be protected by both a guardrail and a fall arrest system. 

Using a railing, ladder, planks, or any other devise for gaining additional height is not permitted on any elevated work platform. Workers must maintain a firm footing on the platform at all times, except for workers on a scissor lift who are wearing a fall arrest system attached to an external anchorage point while exiting the guarded area of the lift or who are attached to a manufacturer approved hardpoint.