By David H. Glabe, P.E. / January 31, 1999

People do the most amazing things. Take the “scaffold” application illustrated in the two photographs. The photos, contributed by Mr. Steve Schuler of Carl Schuler Masonry Construction Company in Waterloo, Iowa, depicts a scaffold constructed of lumber and mounted to a Ford Pick-up Truck. A cursory review of the two photos suggests that the scaffold might be in violation of applicable standards and industry practices. In fact, it’s common to quickly dismiss this scaffold as a ludicrous example of somebody’s idea of a safe scaffold. But wait; what exactly is wrong with this scaffold? Apparently somebody thought this scaffold is okay or they would never have constructed it this way. Let’s look at this wood scaffold (and perhaps a rolling tower) using a methodical approach to evaluating the scaffold so that all aspects are considered when determining the strength, safety, and workability of the scaffold.


A good place to start is by referring to the Five Most Serious Violations pertaining to scaffolds that has been developed by the Federal Occupational Safety and Health (OSHA) Training Institute:


• Unsafe Access

• Falls

• Electrocution

• Struck by Falling Objects

• Scaffold Collapse


What is the access? The photos do not illustrate any typical form of access, such as a ladder or stairway, for any of the platforms. While access could be provided directly from the building, there is no evidence this is the case. (Could it be that the access is mounted to another truck and the operator hasn’t arrived at work with it yet?)


How about fall protection for the workers. Fall protection is required by law for workers who are on scaffold platforms more than ten feet above the lower level. While the lower platform does not require fall protection, the upper platforms appear to be more than ten feet above the ground, thus requiring fall protection. Since there are no guardrails, it must be assumed that the workers will be wearing personal fall protection equipment. What do you suppose might be chosen as the 5000 pound anchor for the lifeline?


Electrocution does not appear to be a hazard, based on these photos. However, since the scaffold is mobile, a “rolling tower,” it is very possible that the scaffold can be driven to another location where interference with electrical lines could be a real possibility. Remember that the minimum distance the scaffold must be from 300 volt lines is 3 feet. Would the driver of this truck even be able to see the electrical lines, much less maintain the minimum distance?


Falling Object Protection is required whenever there is the possibility that objects may fall off a platform and hit a worker below. Typically, protection is provided by toeboards or barricades. Neither is visible in these photos. (In this case, it might be the scaffold itself that will fall and strike the worker below, based on these photos!)


The fifth serious hazard, scaffold collapse, addresses a multitude of sins, including, but not necessarily limited to, platform construction, foundation, component strength, stability, materials used, and bracing. The platforms appear to be more than 18 inches wide, meeting industry and OSHA standards, but are they strong enough to support the anticipated loads? Cleverly, the platforms appear to hinge up for some reason, perhaps to clear the local bridge abutments on the drive home. (Can it be assumed that the scaffold and truck are not driven home each night since it appears over height?) Note that when the scaffold is in position, it is supported by wood and concrete blocks under the bumpers and under the front and rear “outrigger” legs, effectively locking out the truck springs and providing the required stability. Good idea; too bad the erectors used wood blocks and concrete blocks as sills. So much for stability.


From an engineering standpoint, an analysis of the strength of this scaffold could become rather difficult and cumbersome. It is unclear as to how the erector could prove that a sufficient safety factor is being provided. Starting with the truck, the question immediately arises as to whether the truck is a half ton or three quarter ton pick-up. Maybe Ford Motor Company can give us some advice on this. The legs might be adequate since they appear to be 4×4’s with excellent bracing. Unfortunately the real strength is unknown because the connections are unknown. Additionally, since the loads that will be applied to the scaffold are unknown, there is no way to determine if the scaffold has sufficient strength. What grade is the lumber? That is a major factor in determining the strength of a wood scaffold.


As a rolling tower, or more precisely, a mobile scaffold, it can be assumed that the wheels are pinned to the legs but, are there “positive wheel and/or wheel and swivel locks?” (It’s assumed that the rear wheels don’t swivel but some Chevy owners might argue the point.) If one assumes that a power system is being used to propel this mobile scaffold, then one must also assume that the power system was “designed for such use.” (29CFR1926.452(w)(4). Can we assume there will be no riders of the scaffold? And finally, the question that begs the answer; what happens when the “outriggers” are raised and the scaffold is prepared for moving to the next location? That must be quite a sight!


By now, you may be thinking, why wasn’t this guy visited by OSHA? This installation was reported to OSHA in October, 1998, according to Mr. Schuler. As of December 22, 1998, the scaffold, with truck attached, or the truck, with scaffold attached, was still on the project, the same project where a crane tipped over and injured several workers. Where is the training, where is the competent person?


Tags: Scaffolding mobile scaffolds OSHA Standards & Regulations Resources Safety Hazards scaffold violations truck-mounted mobile scaffold

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