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Standard Interpretations
06/10/2002 - Safety Standards regulating the stability of mobile scaffolds, scissor lifts, and aerial work platforms.
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• Standard Number: 1926.452(w); 1926.453; 1926.452(w)(6); 1926.452(w)(5); 1926.453(b)(2)(viii); 1926.453(a)(1); 1926.453(a)(2)

OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA’s interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA’s website at http://www.osha.gov/index.html.


June 10, 2002

Paul S. Walsh
1928 South Park
Up Front North Apartment Buffalo, NY 14220

Re: §§1926.452(w) and 1926.453; scissor lifts and aerial lifts

Dear Mr. Walsh:

This letter is in response to your inquiry addressed to the Occupational Safety and Health Administration dated April 17, 2002 concerning your recollections of a 1999 construction project in Huntsville, Texas.

Thank you for bringing your observations concerning scissor-lift and aerial lift instability to our attention. The scissor-lift tip-over incident and aerial lift movement issues described in your letter illustrate the continuing need for outreach, training, and enforcement.

The Occupational Safety and Health Administration (OSHA) has construction safety standards that address your concerns about the stability of mobile scaffolds and of aerial work platforms.

A scissor-lift or lift cart is considered by OSHA to be a mobile scaffold. It must be used in accordance with the OSHA standards for mobile scaffolds used in construction work. Those standards prohibit employers from letting employees ride on the scaffold unless "the following conditions exist":
The surface on which the scaffold is being moved is within 3 degrees of level, free of pits, holes, and obstructions;

The height to base width ratio of the scaffold during movement is two to one or less, unless the scaffold is designed and constructed to meet or exceed nationally recognized stability test requirements such as those listed in paragraph (x) of Appendix A to this subpart (ANSI/SIA A92.5 and A92.6);

Outrigger frames, when used, are installed on both sides of the scaffold;

When power systems are used, the propelling force is applied directly to the wheels, and does not produce a speed in excess of 1 foot per second (.3 mph); and

No employee is on any part of the scaffold which extends outward beyond the wheels, casters, or other supports.
All that information comes from the Code of Federal Regulations (CFR) for construction safety and may be found at 29 CFR 1926.452(w)(6). From reviewing your letter it seems that you witnessed the result of someone operating a mobile scaffold without following existing OSHA requirements.

For instance, mobile scaffolds must be stabilized to prevent tipping during movement. (This can be found at 29 CFR 1926.452(w)(5).) As we showed in the paragraphs above, the supporting surface for moving scaffolds must be "within 3 degrees of level and free of pits, holes and obstructions." The mobile scaffold you describe was neither stabilized to prevent tipping nor moved on a surface free of pits or holes.

Your concerns over safety requirements for "four-wheel-type extension baskets" are also addressed by existing OSHA construction standards. OSHA includes extension baskets under our Aerial Lifts standard. The standards that regulate use of aerial lifts in construction work are found at 29 CFR 1926.453.

In particular 29 CFR 1926.453(b)(2)(viii) states that:
An aerial lift truck shall not be moved when the boom is elevated in a working position with [workers] in the basket, except for equipment which is specifically designed for this type of operation in accordance with the provisions of paragraphs (a)(1) and (a)(2) of this section.
Additional provisions found in 29 CFR 1926.453(a)(1) and (a)(2) require that aerial lifts meet the appropriate ANSI standard, ANSI A92.2-1969. It was published in 1969, which is the year before OSHA came into existence.

Concerns of many, many others caused Congress in 1970 to write the Occupational Safety and Health Act which, in turn, created this Agency. Those concerns, as you can see, were just like yours are today. Your letter reminds us that we, at OSHA, have muchwork left to do to make America's workplaces safer. We must strive to convince every employer and worker that working safelyincludes following OSHA standards. Again thank you for bringing your concerns to our attention.

Sincerely,



Russell B. Swanson, Director
Directorate of Construction

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