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Scaffold Design Loads

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We are doing a load rating and OSHA compliance check on some permanent
traveling scaffolds (painting scaffolds on a bridge) to determine if
they can be used by a contractor for retrofit construction.   We have
determined tha the CA Code of Regulations, Title 8, Group 4, Article 23,
Mobile Ladder Stands and Scaffolds is contains the governing criteria,
which leads to two questions:

1.	Is there a more appropriate article applying to this type of
work platform?

2.	According to this article, "The desigin load of all scaffolds
shall be calculated on the basis of:" and  goes on to define "light",
"medium" and "heavy" scaffolds as being "designed and constructed to
carry working loads of" 25, 50 and 75 psf, respectively.  These
definitions are followed by the statement: "All ladders and scaffolds
shall be capable of supporting at least 4 times the design working
load".  What does this mean?  Is this a working load versus ultimate
load criteriun?  Or is the 25, 50 or 75 psf "working load" really a
posted load which will then have a FS=4 applied in addition to the
normal FS inherent to the design equations.  (i.e. for a "light"
scaffold, using load factor design, would the live load be 25 psf x 4
and then be factored?) 

Any help in this mnatter would be greatly appreciated.

Tony Powers
HDR Engineering